Developing mobile applications

Introduction to Renderscript

2011-10-03T18:39:00.000-07:00

Renderscript - an important feature of Honeycomb, which was not discussed previously. There will be two articles, this - a simple overview Renderscript, following the same will contain more technical detail and a simple example.

Renderscript - this is a new API, aimed at high performance in 3D rendering and complex computing operations.Renderscript will be of interest to developers who are trying to maximize their overall experience and feel comfortable when working at low levels. For developers, there are three tools: a simple API for 3D rendering that supports hardware acceleration, API to model complex algorithms (similar to CUDA ), and standard language is close to C99 .

Renderscript has been used previously to create a new, more beautiful visually, applications Books and YouTube.He has also been used to write living wallpaper that shipped with Honeycomb.
Improved performance is achieved through the implementation of native code on the device. However, in contrast to the NDK, this solution is cross-platform. Language development for Renderscript - this C99 with some extensions during the development process, it is compiled into a hardware-independent intermediate format and placed in the application package. When the application starts, the script is compiled into native code and optimized. This avoids the problems associated with the need to choose any particular machine architecture.

Renderscript not intended to replace existing high-level API, it should be used in cases where the current need for performance is not provided with the API.

It may seem interesting that nothing was said earlier about where the code runs - on the GPU or CPU. The reason is that it is defined on the device at run time. When there is a corresponding hardware support, simple scripts can be executed on the GPU in a small computational load. More complex scripts run on the CPU (or multiple CPU). The role of the CPU in this case also is to provide a reserve if there is no additional hardware support in the form of suitable GPU. In fact, this should be transparent to the developer. Generally, in the future will be able to run simple scripts in many places, but so far all that is needed in practice - to distribute the load across multiple CPU, supported on the device.

This is a video obtained by image capture from HDMI output on the tablet Honeycomb. It shows Renderscript work. Here we present a "brutforsnuyu" implementation of physics for 900 particles. Computing the script runs each frame a picture and automatically takes advantage of two cores. As soon as the physics simulation is completed, the second graphic script renders an image. In the video we push one of the larger particles, in order to show their interaction. After that, cannot tablet to the work for us has made gravity. The whole process demonstrates good computing power of the new processor A9.

On we went with Honeycomb GL ES 1.1 to 2.0 as to render Renderscript. With version 2.0 we were able to add software support for shaders, download 3D models and more efficient memory management. However, the most important change - that's what Renderscript and related tools are now available to all.

Screenshot shows one of our test applications. Application implements a three-dimensional scene, which shows a recursive call scripts. Androids, shown in the screenshot downloaded from A3D file created in Maya and broadcast from a file Collada . A3D - a format for storing objects Renderscript on the device.

Later, the article will be provided with more technical information and sample code.

How to promote Android apps

2011-10-03T18:35:00.000-07:00

Recently my friend asked me to answer a few questions to promote applications for Android. We dogovorlis that I would write a post. Over the last year I got the definite impression on the market Android Market. I am pleased to share my opinion. I hope my experience will be useful to developers. I would be happy if the post will generate a constructive discussion.

On Android Market:

1. How often do updates for whether these updates in some real bug fixes, or users' trust and silently update "?

As a user I am a "trust and silently update the" application or not at all if I update the application is not interested. Everyone is different and there are users who are always watching the ongoing changes in apdeyte, my IMHO - is dominated by people who install updates, rarely going into the details. There is also a category of applications, in which each update brings new features. As a rule, the loyal users of such applications are always waiting for the upgrade of new functionality or content.
As a developer, I consider that the application needs to update regularly once a week or two. This is for at least two reasons: first regular updates with new features done and content have a positive effect on the formation of a loyal audience of the project, and secondly when you upgrade an application fall into the category of 'Just in', which positively affects the number of downloads. If your application has positive comments and high ratings in the amount of downloads apdeyte much more. It is worth noting that if the update more frequently than once a week, then jump on the downloads will not be because the application does not fall into the 'Just in'.

Empty updates without changes should be avoided. Almost always, (we all without sin!) To update strive to make some new feature or fix bugs. Without bugs is just hello word, so there is always something to improve / fix, especially when it comes to programs for mobile devices. Most likely, frequent updates can empty a negative impact on the audience loyalty and the reputation of the developer. In addition, full update, as a rule, is very effective. IMHO the ideal option - pre-release updates before developit application, even if the first version will be slightly curtailed.

As practice shows, regular updates - it is very important and effective tool in promoting the application, but to achieve some decent results updates are not enough.

2. What is the dynamics of downloads needed and for what period, to reach the top?

Unambiguously answer this question is difficult because the market is changing rapidly. Today in the TOP Free to enter more complicated than in the TOP Paid. My experience is that if there is a 10.5 download within one to two months, you can enter in TOP Paid-100 in its category. TOP Free From a little harder. At various times, I reached up to 30 seats in the TOP Free in its category. My most successful application has 700,000 downloads since April last year, with the first 50,000 downloads were given hard, then went easier. Now this program is contained in the TOP Free 50 in its category with the dynamics of 1000-5000 downloads a day. Over the weekend, more uploads by 20-30%.

3. If the application is free, but there are domestic payments - they are sure to carry through Google Checkout or turning a blind eye to it?

Local payments - a very profitable model, however, on its Android I have not tried it. Considering the vast majority of free applications, I feared that this model would be accepted 'in arms' users. Heard that PayPal has its own In-App Purchase library for Android, but experience with it does not. For domestic payments has some interesting branches on StackOverflow.

4. What statistics are collected - download, many users of versions of what they do in the application, etc.

As I try to make the application as 'light', I do not use a special library to gather statistics. Statistics in my applications library is going to advertise on Mobclix. In the admin I have the opportunity to see 'App Opens' and 'New Users' on the clock, except for direct advertising rates (impressions, eCPM, eCPC, etc.). I agree that the collection of statistics - it is very important, but I do settle for a limited set of parameters.

Promotion:

5. Ever worked with review sites and directories? There is a clear leader, which gives the most downloads? In the event that review and catalog provides a link to the application in the Android Market, is there a way to track exactly which gave life to these downloads Market?

From site surveys worked. I do not think that there is a clear leader, like TouchArcade for iOS. I think that good would result from a review on Pocket Gamer. Ideal - in Google to find as many review sites, sort of Alexei and send all request to Review. The more reviews - the better! Track the number of downloads from a specific review to me it is not possible at this time. You can also order the banners on niche sites. There is a resourceBuySellAds.com, where you can filter and sort advertisements on the android website by visitors and price.You can also apply directly to advertisers on popular websites. Certainly, popular sites are owned media holding, to help you if you wish to learn of the advertising budget.

With regard to third-party alternatives to the directory for Android software, I was not able to achieve the number of downloads, comparable to the Android Market. The main reason for my failure - my laziness. Because a lot of directories and I do updates almost every week, I was very uncomfortable to submit your site updates regularly. So I scored while on the directories. Maybe I just do not see a viable alternative to Android Market. I admit the thought that I would return to the topic later catalogs.

6. Did you work with someone from the advertising networks such as Tapjoy.com, Mdotm.com, Smaato.com? I mean, as an advertiser. By visitors? Most Popular?

As an advertiser mainly worked with AdMob and Mobclix. Budgets content was not very big, so hard to objectively compare. I feel that as a free application to have 10 clicks a instal. Again, much depends on the content of advertisements, descriptions of applications, and screenshots.

7. Placed ads in a contextual advertising Google?

Often advertise the application with AdMob, $ 200 dollars apart for 6-7 hours. According to my statistics, 237 hits have a click (not the best indicator), for $ 200 you can get some clicks and 5000-10000, according to my feelings, 500-1000 downloads. I may be wrong in the calculations.

8. A similar question on the same scale - with whom to work harder to show someone else's advertising in itself why.

As a seller of advertising closely worked with AdMob, Quattro Wirelless and Mobclix. Now I use mostlyMobclix. To date, for my most popular program generated an average of 600-700 thousand hits a day. It should be noted that if the program is popular, it does not always have enough advertising network advertising in order to cater for all application requests. If this happens, you can lose up to 90% of their income. For such cases, there are solutions that provide maximum filling of advertising applications through the automatic replacement of ad networks based on the presence of ads. Today I know two solutions to do it automatically - AdMob + AdWirl and Mobclix. I like the Mobclix, since Mobclix collects all ad networks money, accumulating them at home and make one payment to the developer to all networks. In the case of AdWirl each ad network to get paid separately. On the plus Mobclix also include the ability to use AdMob as an alternative.

Outro

In 2010 I became convinced that developing for Android is not only interesting but also beneficial. On the advertising model and you can earn quite well. In the Android Market today, there are many free niches that can and should take.

I am sure that there are many ways to promote your software for Android. The main thing - do not be afraid to experiment! In no event do not get upset if something does not work and never stop.

Thank you. I would really welcome your comments.

Using Android Search Dialog. Part 3 - Custom Suggestions

2011-10-03T18:26:00.000-07:00

This is the final article on the use of Android Search Dialog (previous are here and here ). In it, I'll show you how to add dynamic dialogue in the search for clues, as well as how to integrate search into your application system Quick Search Box (QSB). QSB advantage that it can be used to obtain information from virtually anywhere in the OS.

Theory

Tips for searching the data generated by your application that are subject to search. When the user selects one of them, the Search Manager sends Intent to Activity, which is responsible for the search. Normally, when a user clicks an icon in the search dialog box, then sent Intent type Search, however, the choice of tips in this case we can define another type of Intent, so that we can intercept it and take appropriate action, such as creating a new dialogue, or call Activity to display information, etc.
The data are transferred via a search query Intent as before, but now we will use the URI, to determine the type of request by the content provider.

Again, we need not perform any action on the rendering of dialogue, is engaged in Search Manager, all that is required of us - to provide a configuration xml file.

So, when the Search Manager determines our Activity as responsible for finding and providing clues to the search, the following sequence of actions occurs:

When the Search Manager receives the search request, it sends a request to the content provider, provides tips.
Content provider returns a cursor that points to clues that coincide with the text search.
Search Manager displays a prompt, using the cursor

Once a list of tips has been mapped, it may be the following:

If the user changes the text of the query, then all of the above steps are repeated.
If the user starts the search, the hints are ignored, and sent to Activity Intent type Search.
If the user selects a clue what to Activity Intent delivered another type (the type is defined in the configuration file) that transfers data as a URI. URI will be used to search for records in the table corresponding to the selected tip.

So, we modify our application (that which was seen in part 1 ) so as to add dynamic prompts, and to develop a mechanism, the choice tips will cause a new Activity, which will display information on request. For the implementation will require:

Edit the configuration file dialog by adding information about the content provider and the type of Intent, used for clues
Create a table in the database SQLite, which will provide the columns needed for Manager'om Search Tips
Create a new content provider that has access to a table hint, and define it in the manifesto
Add Activity, which will display the information in the choice tips

Change the configuration file

I remind you that the configuration file (res / xml / searchable.xml) is required to display the dialog and change it, for example, to use voice search. To use dynamic prompts, you must add a file parameter: android: searchSuggestAuthority. It will coincide with a string of authorization content provider. Besides adding a android: searchMode = «queryRewriteFromText», its value indicates that the search string in the dialog will be overwritten when navigating through the prompts, for example using the trackball. Also add the parameters that define the operator selection, the type of Intent sent to the selection tips, and the minimum number of characters printed in the dialogue necessary to query the content provider.

File res / xml / searchable.xml

<?xml version="1.0" encoding="utf-8"?>
<searchable xmlns:android="http://schemas.android.com/apk/res/android"
    android:label="@string/app_name"
    android:hint="@string/search_hint" 
    android:searchSettingsDescription="@string/settings_description"
    android:searchMode="queryRewriteFromText"
    android:includeInGlobalSearch="true"
    android:searchSuggestAuthority="com.example.search.SuggestionProvider" 
    android:searchSuggestIntentAction="android.intent.action.VIEW"
    android:searchSuggestIntentData="content://com.example.search.SuggestionProvider/records"
    android:searchSuggestThreshold="1"
    android:searchSuggestSelection=" ?">
</searchable>

Create a content provider

In fact, our content provider is no different from others. But to do so for each row of the table prompts to select the correct columns, those that require Search Manager. We will request data on the prompts using the content provider's query (). And he will be called whenever the user types a new character in the dialogue. Thus, query () method must return a pointer to the table entries that match the query, and then Search Manager will display a prompt. See the description of the method in the code comments.
The text itself will be appended to the request URI, so that it will not give problems, you just use the standard method getLastPathSegment ().

Create a table hints

When the cursor gets Search Manager, pointing to the record, it expects a certain set of columns for each record. Binding are two: _ID - unique identifier for each clue and SUGGEST_COLUMN_TEXT_1 - help text.
There are many optional columns, such as using SUGGEST_COLUMN_ICON_1, you can define for each record, the icon shown on the left side tips (very useful, for example, to search for contacts).

Data type definition for Intent

Since we are passing the data on demand through the URI, then we need a mechanism to determine which clue was chosen. There are two ways. The first is to define a column SUGGEST_COLUMN_INTENT_DATA, which will be unique information for each record, then you can retrieve data from across Intent getData () or getDataString (). The second option - the data type for all of Intent in the configuration file (res / xml / searchable.xml) and then append to the URI unique data for each of Intent, using the column SUGGEST_COLUMN_INTENT_DATA_ID.
We will use the second option, with separate columns in the table, I did not create, because you can simply create a map of SUGGEST_COLUMN_INTENT_DATA_ID rowId in the table. I will add that for fun in SQLite to search for used FTS3 , that is, had to create a virtual table that you can not impose restrictions on the columns (constraints), such as a PRIMARY KEY or NULL / NOT NULL. But at the virtual table has a unique ID string, and set it on the map. That is, data for Intent will be as follows: the URI will be appended to "/" and rowId row in the table.

Create Activity to display information

The interface is in res / layout / record_activity.xml. All what the Activity - getting data from Intent, a query cursor over a content provider and display records in text box.

File res / layout / record_activity.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:padding="10dp">
    <TextView
            android:id="@+id/record_header"
            android:textSize="25dp"
            android:textColor="?android:textColorPrimary"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
</LinearLayout>

Now fill out the information on the content provider and a new Activity to the manifest, too, since we now have two Activity, then point out that, by default, is responsible for the search.

File AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.search"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".Main"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <intent-filter>
                <action android:name="android.intent.action.SEARCH" />
            </intent-filter>
            <meta-data 
                android:name="android.app.searchable"
                android:resource="@xml/searchable"
            />
        </activity>

        <activity android:name=".RecordActivity"
                  android:theme="@android:style/Theme.NoTitleBar" />

        <provider android:name=".SuggestionProvider"
                  android:authorities="com.example.search.SuggestionProvider" />

        <meta-data android:name="android.app.default_searchable"
                   android:value=".Main" />
    
    </application>
    <uses-sdk android:minSdkVersion="5" />
</manifest>

Intent to Intercept Activity, responsible for search

After all these steps need to be processed in the main Intent Activity, which is responsible for the search. Since we have determined the type of Intent for clues as View, then you just need to add a check on him. If the condition is satisfied, then starts RecordActivity, using the Intent, in which data is recorded URI + "/" + id tips in the table.

Integration with the Quick Search Box

Once you have modified your application to use custom suggestions, you can add it to the system search. To do this, file searchable.xml need to add two parameters:

android: includeInGlobalSearch = «true» - indicates that QSB can search for your application.
android: searchSettingsDescription = "@ string / settings_description" - points to a description of your application to be displayed when configuring the Quick Search Box. These settings are in settings-> search.

These options are available with version Android 1.6, that is for versions below you can not configure your application to QSB.

Source

Presenting the complete source code for all required classes. Main.java - main Activity, responsible for search and for sending requests to the content provider, RecordActivity.java - Intent receives data on a particular record, gets a reference to record and display information. SuggestionProvider.java - the content provider will handle the requests from the Search Manager'a to the table hints. RecordsDbHelper.java - responsible for creating the table, filling it, the establishment of the necessary maps, and for myself «matching» records.

File Main.java

package com.example.search;

import android.app.ListActivity;
import android.app.SearchManager;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;

public class Main extends ListActivity {
 
    private EditText text;
    private Button add;
    private RecordsDbHelper mDbHelper;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
 mDbHelper = new RecordsDbHelper(this);
  
 Intent intent = getIntent();
  
 if (Intent.ACTION_SEARCH.equals(intent.getAction())) {
     //Берем строку запроса из экстры
     String query = intent.getStringExtra(SearchManager.QUERY);
     //Выполняем поиск
     showResults(query);
 } else if (Intent.ACTION_VIEW.equals(intent.getAction())){
         //Создаем Intent для открытия RecordActivity
                Intent recordIntent = new Intent(this, RecordActivity.class);
                recordIntent.setData(intent.getData());
                startActivity(recordIntent);
                finish();
 }
  
 add = (Button) findViewById(R.id.add);
 text = (EditText) findViewById(R.id.text);
 add.setOnClickListener(new View.OnClickListener() {
     public void onClick(View view) {
         String data = text.getText().toString();
  if (!data.equals("")) {
      saveTask(data);
      text.setText("");
  }
     }
 });
  
    }

    private void saveTask(String data) {
        mDbHelper.createRecord(data);
    }
 
    private void showResults(String query) {

     //Запрашиваем у контент-провайдера курсор на записи 
        Cursor cursor = managedQuery(SuggestionProvider.CONTENT_URI, null, null,
                                new String[] {query}, null);
        if (cursor == null) {
            Toast.makeText(this, "There are no results", Toast.LENGTH_SHORT).show();
        } else {
         //Обновляем адаптер
            String[] from = new String[] { RecordsDbHelper.KEY_DATA };
            int[] to = new int[] { R.id.text1 };
            SimpleCursorAdapter records = new SimpleCursorAdapter(this, R.layout.record, cursor, from, to);
            getListView().setAdapter(records);            
        }        
    }
 

    //Создаем меню для вызова поиска (интерфейс в res/menu/main_menu.xml)
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true; 
    }

    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.search_record:
          onSearchRequested();
         return true;
            default:
            return super.onOptionsItemSelected(item);
        }
    }
}

Файл RecordActivity.java

package com.example.search;

import android.app.Activity;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.TextView;

public class RecordActivity extends Activity {

 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.record_activity);

     //Получаем URI с данными из Intent и запрашиваем данные через контент-провайдер
     Uri uri = getIntent().getData();
            Cursor cursor = managedQuery(uri, null, null, null, null);

        if (cursor == null) {
            finish();
        } else {
            //Устанавливаем данные в текстовое поле
            cursor.moveToFirst();

            TextView record = (TextView) findViewById(R.id.record_header);
            int rIndex = cursor.getColumnIndexOrThrow(RecordsDbHelper.KEY_DATA);

            record.setText(cursor.getString(rIndex));
        }
    }
 
 //Создаем меню для вызова диалога поиска из этого активити
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.search_record:
                onSearchRequested();
                return true;
            default:
                return false;
        }
    }

}

package com.example.search;

import android.app.SearchManager;
import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;
import android.provider.BaseColumns;

public class SuggestionProvider extends ContentProvider{

    private RecordsDbHelper mDbHelper;
    
    public static String AUTHORITY = "com.example.search.SuggestionProvider";
    public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/records");
    
    //MIME типы для getType()
    public static final String RECORDS_MIME_TYPE = ContentResolver.CURSOR_DIR_BASE_TYPE +
                                                  "/vnd.example.search";
    public static final String RECORD_MIME_TYPE = ContentResolver.CURSOR_ITEM_BASE_TYPE +
                                                  "/vnd.example.search";

    //Для матчера разных URI
    private static final int SEARCH_RECORDS = 0;
    private static final int GET_RECORD = 1;
    private static final int SEARCH_SUGGEST = 2;
    private static final UriMatcher sURIMatcher = makeUriMatcher();
               
    @Override
    public boolean onCreate() {
        mDbHelper = new RecordsDbHelper(getContext());
        return true;
    }

    /**
     * Обрабатывает запросы от Search Manager'a.
     * Когда запрашивается конкретный элемент, то требуется только URI.
     * Когда запрашивается поиск по всей таблице, то первый элемент параметра selectionArgs содержит строку запроса.
     * Остальные параметры не нужны.
     */
    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
       String[] selectionArgs, String sortOrder) {
        //Используем UriMatcher, чтобы узнать какой тип запроса получен. Далее формируем соответствующий запрос к БД
        switch (sURIMatcher.match(uri)) {
            case SEARCH_SUGGEST:
                if (selectionArgs == null) {
                    throw new IllegalArgumentException(
                        "selectionArgs must be provided for the Uri: " + uri);
                }
                return getSuggestions(selectionArgs[0]);
            case SEARCH_RECORDS:
                if (selectionArgs == null) {
                    throw new IllegalArgumentException(
                        "selectionArgs must be provided for the Uri: " + uri);
                }
                return search(selectionArgs[0]);
            case GET_RECORD:
                return getRecord(uri);
            default:
                throw new IllegalArgumentException("Unknown Uri: " + uri);
        }
 }
 
    private Cursor getSuggestions(String query) {
        query = query.toLowerCase();
        String[] columns = new String[] {
             BaseColumns._ID,
             RecordsDbHelper.KEY_DATA,
             SearchManager.SUGGEST_COLUMN_INTENT_DATA_ID};
        return mDbHelper.getRecordMatches(query, columns);
    }
    
    private Cursor search(String query) {
        query = query.toLowerCase();
        String[] columns = new String[] {
            BaseColumns._ID,
            RecordsDbHelper.KEY_DATA};

        return mDbHelper.getRecordMatches(query, columns);
    }
    
    private Cursor getRecord(Uri uri) {
        String rowId = uri.getLastPathSegment();
        String[] columns = new String[] {
            RecordsDbHelper.KEY_DATA};

        return mDbHelper.getRecord(rowId, columns);
    }
    
    /**
     * Вспомогательный метод
     * нужен для сопоставления разным URI конкретных значений 
     */
    private static UriMatcher makeUriMatcher() {
        UriMatcher matcher =  new UriMatcher(UriMatcher.NO_MATCH);
        // Для записей
        matcher.addURI(AUTHORITY, "records", SEARCH_RECORDS);
        matcher.addURI(AUTHORITY, "records/#", GET_RECORD);
        // Для подсказок
        matcher.addURI(AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, SEARCH_SUGGEST);
        matcher.addURI(AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", SEARCH_SUGGEST);
        return matcher;
    }
 
    //Требуемые методы (наследуются от класса ContentProvider)
    @Override
    public String getType(Uri uri) {
        switch (sURIMatcher.match(uri)) {
            case SEARCH_RECORDS:
                return RECORDS_MIME_TYPE;
            case SEARCH_SUGGEST:
             return SearchManager.SUGGEST_MIME_TYPE;
            case GET_RECORD:
                return RECORD_MIME_TYPE;
            default:
                throw new IllegalArgumentException("Unknown URL " + uri);
        } 
    }
 
    @Override
    public int update(Uri uri, ContentValues values, String selection,
                   String[] selectionArgs) {
        throw new UnsupportedOperationException();
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        throw new UnsupportedOperationException();
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        throw new UnsupportedOperationException();
    }

}package com.example.search;


import android.app.Activity;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.TextView;

public class RecordActivity extends Activity {

 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.record_activity);

     //Получаем URI с данными из Intent и запрашиваем данные через контент-провайдер
     Uri uri = getIntent().getData();
            Cursor cursor = managedQuery(uri, null, null, null, null);

        if (cursor == null) {
            finish();
        } else {
            //Устанавливаем данные в текстовое поле
            cursor.moveToFirst();

            TextView record = (TextView) findViewById(R.id.record_header);
            int rIndex = cursor.getColumnIndexOrThrow(RecordsDbHelper.KEY_DATA);

            record.setText(cursor.getString(rIndex));
        }
    }
 
 //Создаем меню для вызова диалога поиска из этого активити
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.search_record:
                onSearchRequested();
                return true;
            default:
                return false;
        }
    }

}

File RecordActivity.java

package com.example.search;

import android.app.Activity;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.TextView;

public class RecordActivity extends Activity {

 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.record_activity);

     //Получаем URI с данными из Intent и запрашиваем данные через контент-провайдер
     Uri uri = getIntent().getData();
            Cursor cursor = managedQuery(uri, null, null, null, null);

        if (cursor == null) {
            finish();
        } else {
            //Устанавливаем данные в текстовое поле
            cursor.moveToFirst();

            TextView record = (TextView) findViewById(R.id.record_header);
            int rIndex = cursor.getColumnIndexOrThrow(RecordsDbHelper.KEY_DATA);

            record.setText(cursor.getString(rIndex));
        }
    }
 
 //Создаем меню для вызова диалога поиска из этого активити
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.search_record:
                onSearchRequested();
                return true;
            default:
                return false;
        }
    }

}

File SuggestionProvider.java

package com.example.search;

import android.app.SearchManager;
import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.net.Uri;
import android.provider.BaseColumns;

public class SuggestionProvider extends ContentProvider{

    private RecordsDbHelper mDbHelper;
    
    public static String AUTHORITY = "com.example.search.SuggestionProvider";
    public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/records");
    
    //MIME типы для getType()
    public static final String RECORDS_MIME_TYPE = ContentResolver.CURSOR_DIR_BASE_TYPE +
                                                  "/vnd.example.search";
    public static final String RECORD_MIME_TYPE = ContentResolver.CURSOR_ITEM_BASE_TYPE +
                                                  "/vnd.example.search";

    //Для матчера разных URI
    private static final int SEARCH_RECORDS = 0;
    private static final int GET_RECORD = 1;
    private static final int SEARCH_SUGGEST = 2;
    private static final UriMatcher sURIMatcher = makeUriMatcher();
               
    @Override
    public boolean onCreate() {
        mDbHelper = new RecordsDbHelper(getContext());
        return true;
    }

    /**
     * Обрабатывает запросы от Search Manager'a.
     * Когда запрашивается конкретный элемент, то требуется только URI.
     * Когда запрашивается поиск по всей таблице, то первый элемент параметра selectionArgs содержит строку запроса.
     * Остальные параметры не нужны.
     */
    @Override
    public Cursor query(Uri uri, String[] projection, String selection,
       String[] selectionArgs, String sortOrder) {
        //Используем UriMatcher, чтобы узнать какой тип запроса получен. Далее формируем соответствующий запрос к БД
        switch (sURIMatcher.match(uri)) {
            case SEARCH_SUGGEST:
                if (selectionArgs == null) {
                    throw new IllegalArgumentException(
                        "selectionArgs must be provided for the Uri: " + uri);
                }
                return getSuggestions(selectionArgs[0]);
            case SEARCH_RECORDS:
                if (selectionArgs == null) {
                    throw new IllegalArgumentException(
                        "selectionArgs must be provided for the Uri: " + uri);
                }
                return search(selectionArgs[0]);
            case GET_RECORD:
                return getRecord(uri);
            default:
                throw new IllegalArgumentException("Unknown Uri: " + uri);
        }
 }
 
    private Cursor getSuggestions(String query) {
        query = query.toLowerCase();
        String[] columns = new String[] {
             BaseColumns._ID,
             RecordsDbHelper.KEY_DATA,
             SearchManager.SUGGEST_COLUMN_INTENT_DATA_ID};
        return mDbHelper.getRecordMatches(query, columns);
    }
    
    private Cursor search(String query) {
        query = query.toLowerCase();
        String[] columns = new String[] {
            BaseColumns._ID,
            RecordsDbHelper.KEY_DATA};

        return mDbHelper.getRecordMatches(query, columns);
    }
    
    private Cursor getRecord(Uri uri) {
        String rowId = uri.getLastPathSegment();
        String[] columns = new String[] {
            RecordsDbHelper.KEY_DATA};

        return mDbHelper.getRecord(rowId, columns);
    }
    
    /**
     * Вспомогательный метод
     * нужен для сопоставления разным URI конкретных значений 
     */
    private static UriMatcher makeUriMatcher() {
        UriMatcher matcher =  new UriMatcher(UriMatcher.NO_MATCH);
        // Для записей
        matcher.addURI(AUTHORITY, "records", SEARCH_RECORDS);
        matcher.addURI(AUTHORITY, "records/#", GET_RECORD);
        // Для подсказок
        matcher.addURI(AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, SEARCH_SUGGEST);
        matcher.addURI(AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", SEARCH_SUGGEST);
        return matcher;
    }
 
    //Требуемые методы (наследуются от класса ContentProvider)
    @Override
    public String getType(Uri uri) {
        switch (sURIMatcher.match(uri)) {
            case SEARCH_RECORDS:
                return RECORDS_MIME_TYPE;
            case SEARCH_SUGGEST:
             return SearchManager.SUGGEST_MIME_TYPE;
            case GET_RECORD:
                return RECORD_MIME_TYPE;
            default:
                throw new IllegalArgumentException("Unknown URL " + uri);
        } 
    }
 
    @Override
    public int update(Uri uri, ContentValues values, String selection,
                   String[] selectionArgs) {
        throw new UnsupportedOperationException();
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        throw new UnsupportedOperationException();
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        throw new UnsupportedOperationException();
    }
 
}

___

RecordsDbHelper.java

package com.example.search;


import java.util.HashMap;

import android.app.SearchManager;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.provider.BaseColumns;
import android.util.Log;

public class RecordsDbHelper {

    //Единственный столбец в таблице - данные
    public static final String KEY_DATA = SearchManager.SUGGEST_COLUMN_TEXT_1;

    private static final String TAG = "RecordsDbHelper";
    private DatabaseHelper mDbHelper;
    private SQLiteDatabase mDb;

    private static final String DATABASE_NAME = "datas";
    private static final String DATABASE_TABLE = "records";
    private static final int DATABASE_VERSION = 2;
 
    //Сценарий создания БД
    private static final String DATABASE_CREATE =
  "CREATE VIRTUAL TABLE " + DATABASE_TABLE +
                " USING fts3 (" + KEY_DATA + ");"; 

    private static final HashMap<String,String> mColumnMap = buildColumnMap();
 
    /**
     * Возвращает курсор, указывающий на запись с rowId
     * @param rowId id возвращаемой записи
     * @param columns возвращаемые столбцы записи; если null, то все 
     * @return курсор, указывающий на определенную запись, null - если не запись не найдена
     */
    public Cursor getRecord(String rowId, String[] columns) {
        String selection = "rowid = ?";
        String[] selectionArgs = new String[] {rowId};

        return query(selection, selectionArgs, columns);
    }
    
    /**
     * Возвращает курсор, указывающий на все записи, совпадающие с запросом
     * @param query текст поискового запроса
     * @param columns возвращаемые столбцы записи; если null, то все 
     * @return курсор, указывающий на записи, совпадающие с запросом, null - если не записи не найдена
     */
    public Cursor getRecordMatches(String query, String[] columns) {
        String selection = KEY_DATA + " MATCH ?";
        String[] selectionArgs = new String[] {query+"*"};

        return query(selection, selectionArgs, columns);
    }
    
    /**
     * Создает отображение всевозможных запрашиваемых столбцов.
     * Будет установлено как проекция в SQLiteQueryBuilder.
     * Нужно для того, чтобы назначить для каждой записи уникальные значения SUGGEST_COLUMN_INTENT_DATA_ID
     * которые используются для получения конкретной записи по URI.
     */
    private static HashMap<String,String> buildColumnMap() {
        HashMap<String,String> map = new HashMap<String,String>();
        map.put(KEY_DATA, KEY_DATA);
        map.put(BaseColumns._ID, "rowid AS " +
                BaseColumns._ID);
        map.put(SearchManager.SUGGEST_COLUMN_INTENT_DATA_ID, "rowid AS " +
                SearchManager.SUGGEST_COLUMN_INTENT_DATA_ID);
        return map;
    }

    /**
     * 
     * @param selection оператор выборки
     * @param selectionArgs аргументы, заменяющие "?" в запросе к БД
     * @param columns возвращаемые столбцы записи
     * @return курсор, указывающий на все записи, совпадающие с поисковым запросом
     */
    private Cursor query(String selection, String[] selectionArgs, String[] columns) {
        /* SQLiteBuilder предоставляет возможность создания отображения для всех
         * необходимых столбцов БД, что позволяет не сообщать контент-провайдеру
         * настоящие имена столбцов.
         */

        SQLiteQueryBuilder builder = new SQLiteQueryBuilder();
        builder.setTables(DATABASE_TABLE);
        builder.setProjectionMap(mColumnMap);

        Cursor cursor = builder.query(mDbHelper.getReadableDatabase(),
                columns, selection, selectionArgs, null, null, null);
        if (cursor == null) {
            return null;
        } else if (!cursor.moveToFirst()) {
            cursor.close();
            return null;
        }
        return cursor;
    }    
     
    /**
     *Создает/открывает БД
     */
    private static class DatabaseHelper extends SQLiteOpenHelper {
  
        DatabaseHelper(Context context) {
  super(context, DATABASE_NAME, null, DATABASE_VERSION);
 }

 @Override
 public void onCreate(SQLiteDatabase db) {
     db.execSQL(DATABASE_CREATE);
 }

 @Override
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
     Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
   + newVersion + ", which will destroy all old data");
     db.execSQL("DROP TABLE IF EXISTS records");
     onCreate(db);
 }
    }

    public RecordsDbHelper(Context context) {
        mDbHelper = new DatabaseHelper(context);
    }

    /**
     * Добавляет запись в таблицу
     * @param data данные, сохраняемые в таблицу
     * @return id записи, или -1, если добавление не удалось
     */
    public long createRecord(String data) {
        mDb = mDbHelper.getWritableDatabase();
 ContentValues initialValues = new ContentValues();
 initialValues.put(KEY_DATA, data);
 return mDb.insert(DATABASE_TABLE, null, initialValues);
    }
 
}

The whole project can take on code.google.com

Thank you!

Android-compatible applications on different devices

2011-09-30T15:35:00.000-07:00

It's no secret that the number of devices on the Android large, they differ in hardware, screen size and quality, processing power, and others. Unlike the iPhone-programmers who know for sure on which device will be running their app, Android-developers need to focus on application compatibility with different devices.

This article focuses on the interoperability of applications, especially applications display on screens with different resolutions and diagonals.

First we need to understand the opportunities offered by Android for the screen.

Basics

Screen size (screen size) - the physical size of the screen, the predefined values: small, normal, large, extra large *.

The geometric factor (aspect ratio) - the ratio of the physical proportions of the screen (width to height), pre-defined values: long (for screens whose size exceeds the width or height of a standard screen size), notlong (for screens whose dimensions correspond to the standard).

Density (density) - the distribution of pixels with respect to the physical size of the screen. The density distribution of pixels is important because the same UI element, expressed in pixels for screens with a lower density will appear more than screens high. Predefined values for the density: ldpi (low), mdpi (medium), hdpi (high), and xhdpi *.

Independent (from density) pixel (density-independent or dp) - "virtual" pixel, which can be used to draw the application UI-elements. This pixel is equivalent to the physical pixel on the screen with a density of 160 dpi.During the execution of OS Android draws element in accordance with the formula pixel = dp * (density/160), where the density - density of the screen.

It is also worth noting that OS Android works with the screen resolution, through the values of the density screen (no tools to work directly with the resolution of the developer does not have).

The figure below shows the correlation between density and size of the screen device with predetermined values of these quantities.

* Another point worthy of note: the density xdpi was added to the version of Android 2.2 (API level 8), meaning the screen xlarge - a version of Android 2.3 (API level 9)

Working with the manifest and resource allocation

Starting with version Android 1.6, was added to the manifest tag <support-screens>, which is used to define a class of devices, which may be running. Tag attributes smallScreens, normalScreens, largeScreens, xlargeScreens correspond to certain values above the screen and can be true or false. Default attribute values vary depending on the version of Android (more details can be found here .). In determining the value of an attribute as true, OS Android gets a signal that is compatible with the appropriate type of screen and does not use additional funding for interoperability (which occurs at a value of false). It is also worth noting that these tools (functions) are only for compatibility with larger screen sizes (so, if the value normalScreen - true, the rest - false, the application is also compatible with screens large and xlarge, but not compatible with small) . This tag is also used to filter Market'om Android applications.

The density also has an attribute - anyDensity, which also takes values true / false. If the attribute value - true, OS Android does not use functions for compatibility with different densities of the screen. In this case, the application must use dp for rendering UI elements, or to manage the calculation of the sizes for different densities. If the value - false, OS Android includes functions for scaling the elements in accordance with the density of the screen.

Allocation of resources

OS Android also provides a means to identify resources that will be used for specific screen sizes and densities.Resources are placed in appropriate folders.

res/layout/my_layout.xml // layout for normal screen size

res/layout-small/my_layout.xml // layout for small screen size

res/layout-large/my_layout.xml // layout for large screen size

res/layout-large-land/my_layout.xml // layout for large screen size in landscape mode

res/layout-xlarge/my_layout.xml // layout for extra large screen size



res/drawable-ldpi/my_icon.png // image for low density

res/drawable-mdpi/my_icon.png // image for medium density

res/drawable-hdpi/my_icon.png // image for high density



res/drawable-nodpi/composite.xml // density independent resource

Interoperability support screens

Briefly support mechanism can be described using the following steps:

OS Android gets a tag attribute values support-screens of the manifesto.
Loaded resources for the appropriate screen size and density (this happens regardless of the data obtained in step 1).
In accordance with Clause 1 OS Android includes / does not include features to ensure compatibility.
Produced drawing elements.

General recommendations for creating compliant application

Use the values wrap_content, fill_parent, dp in the mock.
Avoid the use of AbsoluteLayout.
Use class methods ViewConfiguration for standard values size, speed, time.
Use different resources for different values of the density and size of the screen.

Afterword

The article does not cover practical matters related to testing applications on devices with different characteristics of screens, I think it's highlight in a separate post.

Standard application development for Android

2011-09-30T15:33:00.000-07:00

Android developer is faced with large numbers of files and resources designed for different parts of the program.Even after a month he can not remember which file or resource to which belongs.

Material presented below is based on my experience of many development projects for Android and has been tested in several projects. As a result, simple rules pile of files and resources into a readable project, saves time and nerves. Especially when it is convenient to work in a team where the project can join the new programmers.In Eclipse, you can easily find any resources because they are unique, easy-to-find and understandable manner are sorted in any lists. General rules allow convenient easy to read someone else's code and find the necessary resources. Most of these are my personal opinion.

Standard application development Android

The names of all files

The file name is written in small letters, reflect the human-readable name of the element, perhaps a few words.Gap is replaced by an underscore.

Location of user files on an SD card

The root directory for all user files, except for time:
/ Sdcard / project name / example / sdcard / TalentMania /

Catalog for music:
/ Sdcard / project name / sound /, eg / sdcard / TalentMania / sound /
Directory for MIDI:
/ Sdcard / project name / midi /, eg / sdcard / TalentMania / midi /
The directory for graphics:
/ Sdcard / project name / img /, eg / sdcard / TalentMania / img /

Subdirectories for files of various aktiviti:
/ Sdcard / project name / img / title aktiviti / example / sdcard / TalentMania / img / guitar /

Location of temporary files - use the standard functions of a class File:
createTempFile (String prefix, String suffix, File directory)
Creates an empty temporary file in the given directory using the given prefix and suffix as part of the file name.
createTempFile (String prefix, String suffix)
Creates an empty temporary file using the given prefix and suffix as part of the file name.

Location of files in the application resources

The graphics and sounds for use in assetsah (eg library AndEngine) are grouped into the following directories:
MIDI files - assets / midi /
The graphics for sprites - assets / gfx /
TTF fonts - assets / font /
Common files used by different activity are placed in the root. Files used by only one activity are placed in the subdirectory, for example: assets / gfx / guitar /

MP3 files are placed in the directory res / raw /.

Names Icons

In the names of icons prefix describing the type of

Icons ic_ Example: ic_star.png
Will start ic_launcher_ Example: ic_launcher_calendar.png
The icons ic_menu_ Example: ic_menu_archive.png
Status bar icon ic_stat_sys_ or ic_stat_notify_ Example: ic_stat_notify_msg.png
Icons tab ic_tab_ Example: ic_tab_recent.png
Icons dialogue ic_dialog_ Example: ic_dialog_info.png

Buttons

bt_imya_pressed.png (click image) and bt_imya_default.png (default image)
xml describing the animation is stored in drawable! - bt_imya.xml

Layouts

main leyauty correspond to names of callers aktiviti.
ac_nazvanie_klassa.xml - matches the name of the class aktiviti AcNazvanieKlassa.java.

Additional view for this leyauta correspond to names of callers aktiviti + nameac_название_класса_название_view_название.xml view

view_nazvanie_view.xml - general view for different leyautov.
adt_nazvanie_adaptera.xml - leyauta name for the adapter list
dialog_nazvanie_dialoga.xml - the name of dialogue

Names of elements in the layout

Name of the element used in the layout -

For example: android: id = "@ + id / AcMenuTemplateTopPanel" indicates that the element is called "top panel" and is intended for aktiviti AcMenuTemplate

Animation

definition files are stored in the animation res / drawable.
For buttons - bt_imya_anim.png
For animation - anim_имя_активити_имя_анимации.png
If a lot of animation, it is more convenient to place it in a separate directory res / anim

Graphics

Background - bg_orientatsiya_imya.png.
Image - im_imya.png

Name of Package

Aktiviti - activities
Adapters - adapters
Data - data
Dialogs - dialogs
Interfaces - interfaces
Types - views

Name class

Aktiviti - AcNazvanieAktiviti
Adapters for lists - AdtNazvanieAdaptera
Dialogs - DialogNazvanieDialoga
Interface NazvanieInterfeysaInterface

Result

The proposed standard is not a dogma, and always subject to change with the accumulation of empirical experience. I hope to hear feedback and suggestions on this topic. It is interesting to know the experience of other developers.

Recommendations to the style code

2011-09-30T15:29:00.000-07:00

The rules of the Java language

We follow standard conventions for the design of code in Java. We have added to them some of the rules:

Exceptions: never steal and do not ignore them without explanation.
Exceptions: Do not use generic exceptions, but the code in the libraries at the root of the stack.
Finalizers do not use them.
Imports: fully qualify the imports.

Rules for Java libraries

There is agreement about the use of Java libraries and tools for Android. In some cases, the agreement may be modified, for example, such as using the old code that may be using unapproved pattern or a library.

Rules of Java Style

Program is much easier to maintain when all files have a consistent style. We follow the standard style of programming in Java, particular in their Sun Code Conventions for the Java Programming Language , with a few exceptions and additions. This style guide is a detailed and comprehensive and widely used Java community.

In addition, we will be obliged to use these rules to the code:

Comments / Javadoc: write them, use a standard style.
Short methods: do not write huge methods.
Margins should be at the top of the file, or directly in front of a method that uses them.
Local variables: limit the scope.
Imports: android; third party (in alphabetical order); java (x)
Padding: 4 spaces, not tabs.
The string length: 100 characters.
Field names: not public, and non-static fields begin with «m».
Braces: opening braces are not in a separate line.
Abstracts: Use standard annotations.
Abbreviations: abbreviate words as names, for example, XmlHttpRequest, getUrl (), etc.
Style TODO: «TODO: write a description here."
Consistency: see what's around you.

The rules of the Java language

Do not ignore exceptions

You may want to write code that ignores exceptions, such as:

void setServerPort(String value) { try { serverPort = Integer.parseInt(value); } catch (NumberFormatException e) { } }

Do not ever do it. While you think your code will never run into such a condition, or that it does not matter to handle this condition, ignoring exceptions creates hidden problems. You basically have to handle each exception.The specifics of each case depends on the situation.
Acceptable alternatives:

Shift your exceptions to the caller.

void setServerPort(String value) throws NumberFormatException { serverPort = Integer.parseInt(value); }

Throw an exception, according to your level of abstraction

void setServerPort(String value) throws ConfigurationException { try { serverPort = Integer.parseInt(value); } catch (NumberFormatException e) { throw new ConfigurationException("Port " + value + " is not valid."); } }

Catch the error and replace the corresponding value in the block catch {}

/** Set port. If value is not a valid number, 80 is substituted. */ void setServerPort(String value) { try { serverPort = Integer.parseInt(value); } catch (NumberFormatException e) { serverPort = 80; // default port for server } }

Catch the error and throw RuntimeException. It is dangerous to do so only if you still happen if the issue is.

/** Set port. If value is not a valid number, die. */ void setServerPort(String value) { try { serverPort = Integer.parseInt(value); } catch (NumberFormatException e) { throw new RuntimeException("port " + value " is invalid, ", e); } }

Note that the original exception is passed to the RuntimeException. If you use a compiler to Java 1.3, then lower the exception.

If you believe that ignoring an exception in this case occurs, then at least comment on why you think so.

/** If value is not a valid number, original port number is used. */ void setServerPort(String value) { try { serverPort = Integer.parseInt(value); } catch (NumberFormatException e) { // Method is documented to just ignore invalid user input. // serverPort will just be unchanged. } }

Do not catch generic exceptions

Sometimes it's tempting to be lazy with exception handling and write something like this:

try { someComplicatedIOFunction(); // may throw IOException someComplicatedParsingFunction(); // may throw ParsingException someComplicatedSecurityFunction(); // may throw SecurityException // phew, made it all the way } catch (Exception e) { // I'll just catch all exceptions handleError(); // with one generic handler! }

You should not do so. The bottom line is that you may receive an exception, which you did not expect and, eventually, will catch the error at the application level. That is, if someone adds a new exception type, the compiler will not be able to help you understand that this is another error.

There are rare exceptions to this rule: certain test code, or code top level where you want to capture all types of errors (in order to prevent their display in the user interface, or to pursue some kind of batch jobs).

Alternatives to the generalized exclusions:

Intercepts each exception separately in the block catch, after a single try. Maybe it's inconvenient, but it is still the preferred way to catch all exceptions.
Change your code to a more granular error handling with several blocks try. Separate IO of parsing, error handling on a case.
Perebroste exception. In many cases you do not need to handle all exceptions to the current level, just let the method throw them.

Remember: the exception - your friends! Do not get angry when the compiler points to the fact that you do not catches.

Finalizers

What it is: Finalizers - a way to run code before the object is going to the garbage collector.
Pros: can be useful in treatment, particularly external resources.
Cons: there is no guarantee when a finalizer will be invoked and, in general, whether it is called.

Solution: We do not use finalizers. In most cases, all that you need from a finalizer, you can do with exception handling. If you really need a finalizer, then declare the close () and document when it is sure to be invoked.

Imports

The wildcard character in the import

What it is: When you wish to use Class Bar of package foo, there are two ways to do this:

```
import foo.*;
```
```
import foo.Bar;
```

For # 1: Potentially reduces the number of possible import statements.
For # 2: Make it clear which class is actually used. Makes the code more readable for those who support it.

Solution: Use the style # 2 for the import of any Android code. An explicit exception is made for the standard libraries (java.util .*, java.io. *, etc) and code for unit testing (junit.framework .*).

Comments / Javadoc

Each file must have the copyright notice at the beginning. Next come the announcement of the operators package and import, with each block separated by blank lines. They are followed by announcements of a class or interface. Describe what makes the class Javadoc-comments.

/* * Copyright © 2010 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.android.internal.foo; import android.os.Blah; import android.view.Yada; import java.sql.ResultSet; import java.sql.SQLException; /** * Does X and Y and provides an abstraction for Z. */ public class Foo { ... }

Each class is trivial and a public method must contain Javadoc, with at least one sentence that describes what it does. The phrase should begin with a descriptive verb third person. Examples:

/** Returns the correctly rounded positive square root of a double value. */ static double sqrt(double a) { } /** * Constructs a new String by converting the specified array of * bytes using the platform's default character encoding. */ public String(byte[] bytes) { }

You do not need to describe the Javadoc for trivial get and set methods, such as setFoo (), if your Javadoc says only «sets Foo». If a method does something more complex (eg, compliance with certain restrictions, or if his actions have an important effect outside of himself), then it must be documented. And if it is not simply an explanation of what it means to Foo, then you should also document it.

In general, any method that you write can benefit from Javadoc, no matter public or not. Public methods are part of the API, so they require a description of the Javadoc.

To write Javadoc'ov you should follow the Sun Javadoc conventions .

Short methods

Methods should be short and to solve specific problems as much as possible. However, it is clear that some great methods are feasible, so there is no strict limit to the length of the method. If the method is more than 40 rows, then you may want to consider whether we can break it into pieces, without breaking the structure of the program.

Local variables

The scope of local variables should be kept to a minimum. By doing this, you improve the readability and maintainability of code, as well as reduce the likelihood of errors. Each variable must be declared in the deepest unit, which surrounds all the possible locations of the variable.

Local variables must be declared at the place where for the first time to use it. Nearly every local variable needs initializer. If you do not know exactly how to initialize a variable, then you should postpone its announcement until you do not know.

There is one exception, on the block try-catch. If the variable is initialized with the return statement of the method that throws a checked exception, it must be initialized in the block try. If the variable should be used outside the block try, then it is declared in front of him, no matter whether you know exactly how it needs to be initialized:

// Instantiate class cl, which represents some sort of Set Set s = null; try { s = (Set) cl.newInstance(); } catch(IllegalAccessException e) { throw new IllegalArgumentException(cl + " not accessible"); } catch(InstantiationException e) { throw new IllegalArgumentException(cl + " not instantiable"); } // Exercise the set s.addAll(Arrays.asList(args));

But even this case can be avoided by encapsulating try-catch block in the method.

Set createSet(Class cl) { // Instantiate class cl, which represents some sort of Set try { return (Set) cl.newInstance(); } catch(IllegalAccessException e) { throw new IllegalArgumentException(cl + " not accessible"); } catch(InstantiationException e) { throw new IllegalArgumentException(cl + " not instantiable"); } } ... // Exercise the set Set s = createSet(cl); s.addAll(Arrays.asList(args));

The variables in loops to be declared within the operator, unless there are compelling reasons not to do so.

for (int i = 0; i <= n; i++) { doSomething(i); } for (Iterator i = c.iterator(); i.hasNext(); ) { doSomethingElse(i.next()); }

Imports

The order of import statements as follows:

Android imports.
From imports (com, junit, net, org).
java and javax.

To fully comply setting IDE, imports should be the following:

Sorted alphabetically within each group.
Capital letters should be in front of lower case letters (for example, Z in front of a).
The main groups should be separated by a blank line.

Why?
Order such that:

Imports, which people want to see in the first place, are at the top (android).
Imports, which people want to see as a last resort, located at the bottom (java).
People can easily use this style.
IDE can follow this style.

Indentation

We use 4 spaces for blocks. We never use tabs. We use 8 spaces for wrapping, including function calls and assignments, such as correctly as follows:

Instrument i = someLongExpression(that, wouldNotFit, on, one, line);

and so true:

Instrument i = someLongExpression(that, wouldNotFit, on, one, line);

Field names

Not static, not public names begin c «m».
static fields begin with «s».
Other fields begin with a lowercase letter.
Fields public static final (constant) is written entirely in upper case with underscores (ALL_CAPS_WITH_UNDERSCORES)

For example:

public class MyClass { public static final int SOME_CONSTANT = 42; public int publicField; private static MyClass sSingleton; int mPackagePrivate; private int mPrivate; protected int mProtected; }

Braces

For the opening curly brackets are not allocated a separate line, they are in the same line as the code in front of them:

class MyClass { int func() { if (something) { // ... } else if (somethingElse) { // ... } else { // ... } } }

We require braces to the operator environment. The exception is when the condition statement and his body was placed in one line. That is, you can write like this:

if (condition) { body(); // ok } if (condition) body(); // ok

But you can not do:

if (condition) body(); // bad

The string length

Each line of text in the code should be no longer than 100 characters.
Exception: If the comment contains an example of command or URL (it is more convenient to use copy / paste).
Exception: import string may be longer than 100 characters, because people rarely look at them. Also, it simplifies the writing tools.

Abbreviations in names

Think of acronyms and abbreviations as words. The names of the more readable:

Well	Poorly
XmlHttpRequest	XMLHTTPRequest
getCustomerId	getCustomerID

This style is also used when the acronyms and abbreviations - it's full name:

Well	Poorly
class Html	class HTML
String url;	String URL;
long id;	long ID;

Style TODO

Use TODO comments to the code, which is a temporary, short-term, or good, but not perfect. Comments should include «TODO:», for example:

// TODO: Remove this code after the UrlTable2 has been checked in. // TODO: Change this to use a flag instead of a constant.

If your comment is given "In the future, do something," then make sure it includes a specific date (January 1, 2011), or a particular event "Delete after the release of version 2.1".

Consistency

If you change the code, take a moment out to look at the code around you, and to define his style. If it uses the gaps, then you should use them. If the comments contain a small set of stars, then you should use them.

The whole point of the recommendations to the style of code to create a common vocabulary so that people focused on what they say rather than how they speak. We present a global style rules to let people know this language. But the local style is also important. If the code that you add to the file looks dramatically different from what was then the future is to throw the reader out of his rhythm, and will prevent him understand the structure. Try to avoid this.

Settings in the Android-applications

2011-09-30T15:26:00.000-07:00

Interested in the topic of development under Android. I am writing a small application. Faced with the fact that not fully understand how to make settings for the application. A little Googling and found an article that helped to understand. Decided to translate the article for the Russian-speaking community, including some comments to the original.

Options are an important part of applications for Android (and not only on Android - hereinafter translator's note). It is very important - allow users to change application settings, depending on their preferences.

There are two ways to work with the settings in Android - you can create a file in a directory preferences.xml res / xml, or work with the settings from your code. In this article I'll show you how to work with the settings using preferences.xml file.
Elements of the settings have the following attributes:

android: key - the name of the settings on potoromu in the future can get its value
android: title - the title of the item set
android: summary - a brief description of the item set
android: defaultValue - default value

Now available in the following types of components settings:

CheckBoxPreference - a simple checkbox, which returns true or false.
ListPreference - radio group (radioGroup), of which can be selected only one item. Attribute android: entries points to an array with values in res / values / arrays.xml, and android: entryValues an array of signatures.
EditTextPreference - displays a dialog box with the input field. Returns a string as its value.
RingtonePreference - a group of radio buttons to choose a ringtone.
Preference - setting, working as a button.
PreferenceScreen - screen settings. When one PreferenceScreen nested in another, it opens a new screen with the settings.
PreferenceCategory - category settings.

Screen with the settings	EditTextPreference
ListPreference	RingtonePreference
PreferenceScreen

Screenshots above are generated using the following preferences.xml:

<?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> <PreferenceCategory android:title="First Category"> <CheckBoxPreference android:title="Checkbox Preference" android:defaultValue="false" android:summary="This preference can be true or false" android:key="checkboxPref" /> <ListPreference android:title="List Preference" android:summary="This preference allows to select an item in a array" android:key="listPref" android:defaultValue="digiGreen" android:entries="@array/listArray" android:entryValues="@array/listValues" /> </PreferenceCategory> <PreferenceCategory android:title="Second Category"> <EditTextPreference android:name="EditText Preference" android:summary="This allows you to enter a string" android:defaultValue="Nothing" android:title="Edit This Text" android:key="editTextPref" /> <RingtonePreference android:name="Ringtone Preference" android:summary="Select a ringtone" android:title="Ringtones" android:key="ringtonePref" /> <PreferenceScreen android:key="SecondPrefScreen" android:title="Second PreferenceScreen" android:summary="This is a second PreferenceScreen"> <EditTextPreference android:name="An other EditText Preference" android:summary="This is a preference in the second PreferenceScreen" android:title="Edit text" android:key="SecondEditTextPref" /> </PreferenceScreen> <Preference android:title="Custom Preference" android:summary="This works almost like a button" android:key="customPref" /> </PreferenceCategory> </PreferenceScreen>

Attributes android: entries and android: entryValues ListPreference a link to @ array / listArray and @ array / listValues respectively. The values are taken from the res / values / arrays.xml, which in this case is as follows:

<?xml version="1.0" encoding="utf-8"?> <resources> <string-array name="listArray"> <item>Number 1</item> <item>Number 2</item> <item>Number 3</item> <item>Number 4</item> </string-array> <string-array name="listValues"> <item>1</item> <item>2</item> <item>3</item> <item>4</item> </string-array> </resources>

In order to show the user screen with the settings to create nebhodimo aktiviti inherited from PreferenceActivity.Aktiviti example:

package org.kaloer.preferenceexample; import android.app.Activity; import android.content.SharedPreferences; import android.os.Bundle; import android.preference.Preference; import android.preference.PreferenceActivity; import android.preference.Preference.OnPreferenceClickListener; import android.widget.Toast; public class Preferences extends PreferenceActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.preferences); // Get the custom preference Preference customPref = (Preference) findPreference("customPref"); customPref .setOnPreferenceClickListener(new OnPreferenceClickListener() { public boolean onPreferenceClick(Preference preference) { Toast.makeText(getBaseContext(), "The custom preference has been clicked", Toast.LENGTH_LONG).show(); SharedPreferences customSharedPreference = getSharedPreferences( "myCustomSharedPrefs", Activity.MODE_PRIVATE); SharedPreferences.Editor editor = customSharedPreference .edit(); editor.putString("myCustomPref", "The preference has been clicked"); editor.commit(); return true; } }); } }

A call to the settings aktiviti by clicking on the button on our main aktiviti:

 @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button prefBtn = (Button) findViewById(R.id.prefButton); prefBtn.setOnClickListener(new OnClickListener() { public void onClick(View v) { Intent settingsActivity = new Intent(getBaseContext(), Preferences.class); startActivity(settingsActivity); } }); }

To use the settings values exposed, add a method getPrefs () in the main aktiviti you want to call in the eventonStart (). You must use exactly onStart (), but not onCreate (), to be sure that the current settings are used, rather than those that were at the time the Glan aktiviti. Our method getPrefs () might look something like this:

 boolean CheckboxPreference; String ListPreference; String editTextPreference; String ringtonePreference; String secondEditTextPreference; String customPref; private void getPrefs() { // Get the xml/preferences.xml preferences SharedPreferences prefs = PreferenceManager .getDefaultSharedPreferences(getBaseContext()); CheckboxPreference = prefs.getBoolean("checkboxPref", true); ListPreference = prefs.getString("listPref", "nr1"); editTextPreference = prefs.getString("editTextPref", "Nothing has been entered"); ringtonePreference = prefs.getString("ringtonePref", "DEFAULT_RINGTONE_URI"); secondEditTextPreference = prefs.getString("SecondEditTextPref", "Nothing has been entered"); // Get the custom preference SharedPreferences mySharedPreferences = getSharedPreferences( "myCustomSharedPrefs", Activity.MODE_PRIVATE); customPref = mySharedPreferences.getString("myCusomPref", ""); }

And lastly, do not forget to add aktiviti created with the settings in androidmanifest.xml and add a new row with the name «set_preferences», to refer to the title screen with the settings, for example, «Preferences».

<activity android:name=".Preferences" android:label="@string/set_preferences"> </activity>

As a result, we obtain the following:

Screen with the main aktiviti

Aktiviti with the settings

Android. Create a file manager

2011-09-30T15:23:00.000-07:00

Android - a promising and rapidly growing operating system. And many programmers want to learn how to program applications for OS Android, but a quick search of structured materials in the Internet and, in particular, Lesbian, leads them into a stupor. Indeed, there is still a problem finding tutorials (especially in Russian) to develop applications for this very popular operating system.
Well, we will gradually improve the situation with Habra.
I shall warn that the materials are intended for those who do not have experience in developing applications for Android, but very, very much wants to get this experience.

Getting ready

The first thing we need - to install and configure the IDE. We will use Eclipse, but it is important to note that it is possible to use any development environment.
Detailed instructions for installing and configuring IDE Eclipse is contained in the documentation for Android site .In brief:

Install Eclipse Classic from here
Install SDK Starter Package here
Set ADT Plugin using this manual , for the same instructions perform the steps described in the section Configuring the ADT Plugin
Launch Eclipse, click Window> Android SDK and AVD Manager and select the necessary components for installation. The easiest option - to select all but the bare minimum - SDK Platform Android 2.1 (or 2.2), Android SDK Tools, Android SDK Platform-tools

After all this we have an operating environment for developing applications for OS Android. But we need a place to test our application, right? And here we face a choice - either to perform these actions in the emulator or on a real device.
The emulator can be added to the familiar box, Android SDK and AVD Manager, clicking the New ... tab inVirtual Devices. Fill in the field Name, specify the version of the API and add our virtual device.

If you want to test their applications on a real device, see here . It is important to note that in the end you still have to verify its application on a real device, because a little strange to release the application, for example, in the Android Market, as it should be no testing the samples at the existing phone / tablet.

Create Project

It's time to create a new project. To do this, click File> New> Project, select the pop-up window Android> Android Project and click Next. The following window appears, which we fill like this:

Now a little explanation.
Project Name - name of the project in Eclipse.
Application Name - the name of the application, the one that users will see on the final Android-device.
Package Name - the name of the package. Everything is just like any Java-project. It is important to know that the name must be unique among all the available packages on the target device. Therefore quite effective classical logic to give a name of the Web domain, recorded on the contrary (as here - ru.alwake), and then - the name of the project. This step is in some way provide a unique name.
Create Activity - the name of the class, which in future will be a subclass of Activity.
Min SDK Version - the minimum version of SDK. If you look at the above list in the Build Target window, we can conclude that our application runs only for devices with Android> = 2.1 (Android 2.1 SDK version corresponds to 7). In this case, it's not very principled, but so be it.

Now you can safely click Finish and contemplate your project in the panel Package Exploper. The project was created and would be nice to get acquainted with some theoretical basis for the Android-device applications, which is well presented here .

About our project

First let's define what we want from our file manager. Ideally - the complete replacement of ASTRO and eStrongs. In the meantime, we need to provide basic navigation through catalogs, and a "base" we mean that we do not need to go into those folders, which has access to only root. In addition, in the above, we will display our current location in directory structure.

Well, first let's talk about the structure of the project:

/ Res/drawable- * dpi - in these three locations we found resources to different extensions of the screen. At the moment there is only the file icon.png, then there is an icon of our application.
/ Res / layout - this folder contains the xml-files that describe the appearance of various forms and form elements. After creating the project there is a file main.xml, there is also need to create a row.xml, which will describe the appearance of each individual series (ie a list item of the tree of our file.)
/ Res / values - here we are any constants that we use in our project.

It should be noted that these XML-files can be edited in visual mode or in text (changing directly xml-code). We will act on the second method. To edit the code, you can right-click on the xml-file in the Package Explorer pane and choose Open with> Text Editor. This is so in the future;)

File FileManager.java - in the file actually contains our main class for the main and only form of application. All of our code in this project will be posted here.
File AndroidManifest.xml - file with the basic properties of our project, particularly given when creating the project (such as, for example, the name). Accordingly, to change, let's name, we need to pick the file.

The remaining files we do not really care.

Start writing code

In general, everything that was greater - the basic information that every programmer must Android-know. And now it's time to deal directly with our code.

File main.xml:

<? xml version ="1.0" encoding ="utf-8" ? > < TableLayout xmlns:android ="http://schemas.android.com/apk/res/android" android:orientation ="vertical" android:layout_width ="fill_parent" android:layout_height ="fill_parent" > < TableRow > < TextView android:id ="@+id/titleManager" android:layout_width ="fill_parent" android:layout_height ="fill_parent" android:padding ="5dip" /> </ TableRow > < TableRow > < ListView android:id ="@id/android:list" android:layout_width ="fill_parent" android:layout_height ="fill_parent" android:layout_weight ="2" android:drawSelectorOnTop ="false" /> </ TableRow > </ TableLayout > * This source code was highlighted with Source Code Highlighter .

Here we set the markup for our basic layout of the form. TableLayout here means that the elements we have lined up in a table. Then at the top table cell element is placed TextView (text box), and the bottom cell - ListView (list). Both elements have id, using which we can modify the contents of the elements. For example, using R.id.titleManager for our text field TextView.

File row.xml:

<? xml version ="1.0" encoding ="utf-8" ? > < TextView xmlns:android ="http://schemas.android.com/apk/res/android" android:layout_width ="fill_parent" android:layout_height ="40sp" android:padding ="5dip" android:gravity ="center_vertical" /> * This source code was highlighted with Source Code Highlighter .

Here we set the markup for each item in our ListView, that is, directly to each individual folder or each file. In this code we set the width of each element, height, padding (padding) and alignment center_vertical - ie Center the vertical.

File FileManager.java:

package ru.alwake.filemanager;

import java.io. File;

import java.util. ArrayList;

import java.util. List;

import android.app.AlertDialog;

import android.app.ListActivity;

import android.content.DialogInterface;

import android.content.Intent;

import android.content.DialogInterface.OnClickListener;

import android.net. Uri;

import android.os.Bundle;

import android.view.View;

import android.widget.ArrayAdapter;

import android.widget.ListView;

import android.widget.TextView;

public class FileManager extends ListActivity {

private List <String> directoryEntries = new ArrayList <String> ();

private File currentDirectory = new File ("/");

/ / When application started

@ Override

public void onCreate (Bundle icicle) {

super.onCreate (icicle);

/ / Set main layout

setContentView (R.layout.main);

/ / Browse to root directory

browseTo (new File ("/"));

}

/ / Browse to parent directory

private void upOneLevel () {

if (this. currentDirectory.getParent ()! = null) {

this. browseTo (this. currentDirectory.getParentFile ());

}

}

/ / Browse to file or directory

private void browseTo (final File aDirectory) {

/ / If we want to browse directory

if (aDirectory.isDirectory ()) {

/ / Fill list with files from this directory

this. currentDirectory = aDirectory;

fill (aDirectory.listFiles ());

/ / Set titleManager text

TextView titleManager = (TextView) findViewById (R.id.titleManager);

titleManager.setText (aDirectory.getAbsolutePath ());

} Else {

/ / If we want to open file, show this dialog:

/ / Listener when YES button clicked

OnClickListener okButtonListener = new OnClickListener () {

public void onClick (DialogInterface arg0, int arg1) {

/ / Intent to navigate file

Intent i = new Intent (android.content.Intent.ACTION_VIEW, Uri. Parse ("file: / /" + aDirectory.getAbsolutePath ()));

/ / Start this activity

startActivity (i);

}

};

/ / Listener when NO button clicked

OnClickListener cancelButtonListener = new OnClickListener () {

public void onClick (DialogInterface arg0, int arg1) {

/ / Do nothing

/ / Or add something you want

}

};

/ / Create dialog

new AlertDialog.Builder (this)

. SetTitle ("Confirmation") / / title

. SetMessage ("Want to open file" + aDirectory.getName () + "?") / / Message

. SetPositiveButton ("Yes", okButtonListener) / / positive button

. SetNegativeButton ("No", cancelButtonListener) / / negative button

. Show (); / / show dialog

}

}

/ / Fill list

private void fill (File [] files) {

/ / Clear list

this. directoryEntries.clear ();

if (this. currentDirectory.getParent ()! = null)

this. directoryEntries.add ("..");

/ / Add every file into list

for (File file: files) {

this. directoryEntries.add (file.getAbsolutePath ());

}

/ / Create array adapter to show everything

ArrayAdapter <String> directoryList = new ArrayAdapter <String> (this, R.layout.row, this.DirectoryEntries);

this. setListAdapter (directoryList);

}

/ / When you clicked onto item

@ Override

protected void onListItemClick (ListView l, View v, int position, long id) {

/ / Get selected file name

int selectionRowID = position;

String selectedFileString = this. DirectoryEntries. Get (selectionRowID);

/ / If we select ".." then go upper

if (selectedFileString.equals ("..")) {

this. upOneLevel ();

} Else {

/ / Browse to clicked file or directory using browseTo ()

File clickedFile = null;

clickedFile = new File (selectedFileString);

if (clickedFile! = null)

this. browseTo (clickedFile);

}

}

}

* This source code with WAS Highlighted Source Code Highlighter .

At the beginning of specified package name (package name).
Rows 2-18 are responsible for the import we need libraries. It is important to note that the import libraries, Eclipse can be done automatically, as soon encounters anything unknown.
In this code, we only have five fairly obvious functions, which is easy to understand. And it is - a skeleton application, which provides the main navigation on the file structure. However, in this application there is one problem - when you try to go to the directory to which access is allowed only by root, we get an error and the application quits.
Accordingly, the next time we think about how to get rid of this error and how to display icons corresponding to the type of file. In addition, we will think about implementing the function Copy-Paste in our file manager.

Eventually supposed to get big and clever application that should give basic information about aspects of programming for Android.

The idea and some of the implementation of the file manager is taken from anddev.org
I would also like to announce that the next part will AndroidDev twentieth of January.

Write your first application on Android

2011-09-30T15:18:00.000-07:00

Preface

The purpose of this post - on the one hand to share their successful experience in start developing applications for the Android platform and on the other hand contribute to the development of the market of software for this remarkable and rapidly growing platform for the account (without false modesty, I say) you may have read this post. The network, of course, you can find information on application development, "a little more complicated than helloworld», but as a rule they scattered and they do not describe the various small underwater stones. In this post we look at the full cycle of application development, starting with a clean computer to finished apk-file.Under the cut screens.

Preparing for development

In order to prepare for the development does not require any special actions and manipulations. Will describe the steps you need to do. I is Windows XP, so all should be classified nizheskazannoe it to the OS, although the action without some major changes can be applied to other Windows OS, even Linux.

Installing the Eclipse development environment
Install the ADT Plugin for Eclipse
Installing JDK and JRE
Install Android SDK

Installing the Eclipse development environment

It's simple. Go to the Downloads section on the official site and download version of the Classic. Then simply unzip the file wherever you want, but I decided to do it in an honorable directory C: \ Eclipse

Install the ADT Plugin for Eclipse

Start Eclipse, and open dialogue install the plugin via the menu Help → Install new software. In the Work with the load address is entered plug dl-ssl.google.com/android/eclipse / (if not obtained, the plugin can be downloaded and installed manually on the link http://developer.android.com/sdk/eclipse-adt. HTML ), then in the table below appear Developer Tools, mark it and go on.

After successful installation, you can restart the environment Eclipse.

Setting the Environment for Java: JDK and JRE

If you have not already installed Java Development Kit (JDK) and Java Runtime Environment (JRE), then they must be installed. This can be done on site Oracle . Download and install JDK and JRE.

Install Android SDK

The point now we need to - this is to download and install a fresh Android SDK. This is done on site for Android developers . I personally install the SDK again in the director emeritus of C: \ Android. After that, you need to add a platform and other additional elements SDK. I added all the available versions, since the application and plan to do to early platforms, as well as USB-driver and application examples.

Preparation for the development is completed. Now the next step - the creation of an application.

Create Android-application

Before creating your first application, you can create a virtual Android-device, to quickly test it svezhenapisanny your software. First, I want to say a few words about the Android Virtual Device (AVD). This is a virtual smart phone running Android, which you can easily run you have created the program. As you can see the advantage of Android Virtual Device is that you can see clearly how your program will run on different smart phones with Android, rather than buying the entire range and test the application on each of them.

Let's create a virtual device Android. Follow the menu on the path Window → Android SDK and AVD Manager.

Choose New from the right side of the window in the window we enter the name of the virtual appliance platform (say Android 2.1), the size of the memory card (say 512 Mb), display type (for example HVGA). Then press down the button Create AVD.

Now create a project. To do this, follow the path to the menu File → New → Other, from the list of Android → Android Project.

As an example, talk about the development of one of my simple program UfaTermometr, showing the current temperature with sensors located on one of the objects of the local energy company.

After creating the project, to the left you will see a directory tree. First and foremost, upload your application icon, or rather three icons for different options. In the folder drawable-hdpi ship png-image with a transparent background, size 72x72, in drawable-mdpi respectively 48x48 and drawable-ldpi the smallest size of 36x36. You can do this by dragging and dropping files directly on the tree. The next step will be the controls. In my program had to be all three elements of the interface: ImageView (just a picture logo of the application), Button (update the value of temperature), and TextView (output temperature). All of these controls must be described in a special xml-file. The tree is located at res → layout → main.xml. In many respects layout of controls is similar to the layout of Web pages, and there is padding, and margin, and the analog align. Main.xml my application code:

<? xml version ="1.0" encoding ="utf-8" ? > < LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android" android:orientation ="vertical" android:layout_width ="fill_parent" android:layout_height ="fill_parent" > < ImageView android:layout_width ="fill_parent" android:layout_height ="wrap_content" android:src ="@drawable/droid" android:layout_gravity ="center_horizontal|center" android:layout_margin ="0px" /> < Button android:id ="@+id/refrbutton" android:layout_width ="wrap_content" android:layout_height ="wrap_content" android:gravity ="center_horizontal" android:layout_gravity ="center_horizontal|center" android:textSize ="30px" android:padding ="20px" android:layout_marginTop ="10dip" android:text ="Обновить" /> < TextView android:layout_width ="fill_parent" android:layout_height ="wrap_content" android:text ="..." android:textSize ="100dip" android:gravity ="center_horizontal" android:id ="@+id/temper" android:textColor ="#EEE3C4" /> </ LinearLayout >

Detail the layout of controls will not, because it's fairly detailed in the manual and generally intuitive, especially to someone who had to deal with html / css-layout and / or development of any visual medium (eg, Delphi) . The only note I uploaded the image in any ImageView. In the src is the path that starts with the @ symbol and then specify the address of the tree. In your early res I created a subfolder drawable and "threw" logo there, and then just have ImageView way. Easy? For me that much.

Application code is located directly on the path src → «name your package» → «name of the application». Java.
By default, a "Plural" main class and she is more you can dance. I will not dwell on the intricacies of such a simple code as in my example, but explain that logic is explained by three simple steps:

Download HTML-page with the values of temperature
With regulyarok "pull" the temperature
Show TextView temperature

Note that when an application requires some kind of system permissions, you must specify them in the manifestAndroidManifest.xml. In this particular case we are using to connect to the Internet, respectively, add the line <uses-permission android:name=«android.permission.INTERNET»/> in the above xml-file.
Actually the code that implements the above logic works:

package app.test.ufatermometr; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.TextView; import android.widget.Button; import java.io.InputStreamReader; import java.net.URL; import java.net.URLConnection; import java.util.regex.*; public class UfaTermometr extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final Button button = (Button) findViewById(R.id.refrbutton); button.setOnClickListener( new Button.OnClickListener() { public void onClick(View v) // клик на кнопку { RefreshTemper(); } }); RefreshTemper(); // при запуске грузим температуру сразу }; //---------------------------------------------------------------- public String GetTemper(String urlsite) // фукция загрузки температуры { String matchtemper = "" ; try { // загрузка страницы URL url = new URL(urlsite); URLConnection conn = url.openConnection(); InputStreamReader rd = new InputStreamReader(conn.getInputStream()); StringBuilder allpage = new StringBuilder(); int n = 0; char [] buffer = new char [40000]; while (n >= 0) { n = rd.read(buffer, 0, buffer.length); if (n > 0) { allpage.append(buffer, 0, n); } } // работаем с регулярками final Pattern pattern = Pattern.compile ( "<span style=\"color:#[a-zA-Z0-9]+\">[^-+0]+([-+0-9]+)[^<]+</span>[^(а-яА-ЯёЁa-zA-Z0-9)]+([а-яА-ЯёЁa-zA-Z ]+)" ); Matcher matcher = pattern.matcher(allpage.toString()); if (matcher.find()) { matchtemper = matcher.group(1); } return matchtemper; } catch (Exception e) { } return matchtemper; }; //---------------------------------------------------------------- public void RefreshTemper() { final TextView tTemper = (TextView) findViewById(R.id.temper); String bashtemp = "" ; bashtemp = GetTemper( "http://be.bashkirenergo.ru/weather/ufa/" ); tTemper.setText(bashtemp.concat( "°" )); // отображение температуры }; }

Once the application is written, it is possible to debug and test.

Running and testing applications

We remember about our virtual machine and run the usual button menus or Run → Run

Here's a picture we can then contemplate:

Now, if you want to share an application, you need to collect apk-file. For this we use the menu File → Export,and the list of Android → Export Android application. Next, select the project, then create a keystore keystore and the key key, this will need to fill in a few fields with all sorts of background information. The resulting file can be apk-distribute and even put in the Android Market, but you have to register and pay $ 25, which is in general a bit, especially for the standing of the project. But registration in markets, perhaps another article.

Conclusion

In conclusion I would say that certainly develop applications for Android is pleasant, is rather simple and interesting. Of course, we have considered only the tip of the iceberg, but I hope in the minds of those of you who have not tried doing anything like that "light bulb lit up," and it is possible that once your application will be in the millions.

Sources, references

A post materials are used:
www.ibm.com
www.itblog.name
Wikipedia

APK-application file

UPD: Eliminating Errors

Defite :
1. Error

ERROR: Unable to open class file C: \ workspace \ Test \ gen \ com \ example \ test \ R.java: No such file or directory

solved cleaning project in the menu Project → Clean or restart Eclipse.
2. When an error occurs

emulator: ERROR: no search paths found in this AVD's configuration. Weird, the AVD's config.ini file is malformed. Try re-creating it

- A consequence of the fact that you have a Cyrillic user name. Solved: go to the Computer → System Properties → Advanced Settings → System Environment Variables. Create a new variable name and value ANDROID_SDK_HOME - by where the folder AVD (for example, C: \ Android \). Create, then looking in the same variable, Path, open and in the field of values, separated by semicolons to add the path to the folder tools Android SDK (for example, C: \ Android \ tools). Save. Launch Eclipse, run the program.

The basic UI design patterns Android apps

2011-09-30T15:16:00.000-07:00

Since the development of applications for Android is gaining popularity, think review of major UI patterns for Android-applications will be useful to someone. Pending patterns: Dashboard, Action Bar, Quick Actions, Search Bar and Companion Widget.

In my opinion theme UI patterns is important for several reasons:

Attracting users: patterns help make the application more usability, easier to understand.
Entrance to the market: following patterns may play an important role in promoting the application on the app market'y.
It is not necessary to build a bicycle with a knowledge of patterns is much easier to be engaged in designing application interface, using existing solutions.

The principles of interface design, marked by engineers Google:

Simple vs Clear: the interface should be simple (not loaded) and clear to use
Content vs Chrome: you must use the maximum screen at the same time reduce its visual complexity (use a limited number of buttons / icons)
Consistent yet engaging: consistency of user input - the user needs to understand what he is doing / how to do what he needs
Enhanced by cloud: the user data should be stored in the cloud, the user should be able to choose the settings (to organize your data) once, without repeated actions.

UI Design Patterns (by analogy with Software Design Patterns) describes a general solution for the re-emerging problems / issues and appear as a "byproduct" of the process of development.

The five UI patterns with examples based on the well-known applications .

DashBoard

Dashboard (Dashboard) - represents the major features of the application, is the main application menu.Dashboard occupies the entire screen, is focused on 3-6 most important features of the application may also contain information about the updates.
Because the pattern is essentially the Dashboard application entity, approach to its development should especially carefully.

Action Bar

Action Bar provides quick access to additional functions of the application is the best solution representation of the functions used from any application (search, sync, refresh, etc.).
Action Bar is not meant to replace the menu, but it contains the key actions that the user can execute (you should not be included in the menu to perform these actions). In this pattern should not contain any contextual actions (such as copy / paste) Action Bar can also be used to guide the user in the application (namely, to show him where he is).

Quick Actions

Quick Actions - provides access to contextual features an application is invoked when you click on the "purpose" is displayed on the Eran as a popup. Key features of Quick Actions: actions must match the context, be simple and straightforward (you can use icons) and actions should not be much. It is also worth noting that pop-up popup shall not overlap with the "goal" (to appear either below or above in relation to "purpose"). Use this pattern is recommended when there is no detailed description of the item-a, as well as when your application needs to perform additional actions related to the context. Quick Actions should not be used when available multiselekt.

Search Bar

Search Bar - used to search for the application (replace the Action Bar). Search Bar should support proposals seeking, and may also include a selector for selecting the type of search.
Recommendations for implementing the pattern: to be used for a simple search on the application, provide a rich supply of search (for example, the icon title and description).

Companion Widget

Companion Widget - Widget presents basic information about the application can be configured by the user. In addition to icon should be the content (description, icon update, maybe some features of the application) must save the desktop space, and allow the user to customize the appearance of the widget.
Google engineers are encouraged to give more attention to this element of the interface because it is important in the interaction with the user. A simple shortcut to the application - not the best solution.

The above patterns are fundamental in the development of Android applications, but it does not mean that all of them must be applied. The main idea is still the basis of which it is possible to consider different solutions (it is to ensure that it is worth developing the idea, not the pattern).
Good luck with your ideas!

Android, the history of the first application

2011-09-30T10:03:00.000-07:00

Preface

Good day. I hasten to note that this post does not pull or how much a benefit, it's only a story of a beginner, novice, telling about the beginning of my conquest of the android. Let's begin.

The idea to write his first in the life of an application for android appeared spontaneously. Basic knowledge of java were available, and in my head immediately got the idea to write a program to send SMS through serviceorangetext.md (yes, this is the Republic of Moldova). This proved harder than I thought at first glance.

Beginning

First Things First I decided to start the program interface. For me was a pleasant surprise that the whole interface is created in the xml file. For an application I needed 4 boxes for text input, two for its display, one to display a capture images, and a submit button. In the sample code to show only one example for each:

< code ><? xml version ="1.0" encoding ="utf-8" ? > < AbsoluteLayout android:id ="@+id/widget32" android:layout_width ="fill_parent" android:layout_height ="fill_parent" xmlns:android ="http://schemas.android.com/apk/res/android" android:background ="@drawable/bbg" > < TextView android:id ="@+id/widget41" android:layout_width ="27px" android:layout_height ="20px" android:text ="От:" android:textStyle ="bold" android:layout_x ="12px" android:layout_y ="12px" > </ TextView > < EditText android:id ="@+id/widget42" android:layout_width ="192px" android:layout_height ="30px" android:textSize ="18sp" android:layout_x ="37px" android:layout_y ="9px" > </ EditText > < Button android:id ="@+id/widget54" android:layout_width ="186px" android:layout_height ="34px" android:text ="Отправить" android:layout_x ="30px" android:layout_y ="228px" > < ImageView android:id ="@+id/widget56" android:layout_width ="97px" android:layout_height ="35px" android:layout_x ="19px" android:layout_y ="162px" > </ ImageView > * This source code was highlighted with Source Code Highlighter .

I will not hide, used to mark the program Droid Draw (http://www.droiddraw.org/). The second issue was for me, how to use it all in the program. It turned out easier to nowhere. It was necessary only to indicate with findViewById () on an already created object in our xml file.

ImageView imgView = (ImageView) findViewById (R. id. Widget56);
final EditText nume = (EditText) findViewById (R. id. widget42);
final EditText prefix = (EditText) findViewById (R. id. widget45);
final EditText number = (EditText) findViewById (R. id. widget46);
final EditText message = (EditText) findViewById (R. id. widget50);
final EditText captchatext = (EditText) findViewById (R. id. widget53);
final TextView io = (TextView) findViewById (R. id. widget87);
Button sendSMS = (Button) findViewById (R. id. Widget54);

And then began the most interesting. It turns out orangetext.md the first request to send requests the cookies, hanging at the beginning, he was received by a simple String headerValue = con.getHeaderField (6), but it also asks eventvalid values and viewstate. For me it was a huge screeching halt, because I had no idea where he takes them. It turned out they fit into the HTML, and from where I was pulled out by simple manipulations. From the same was received id captcha images, which I later used to display it.

url = new URL (" www.orangetext.md / Default.aspx " );
con = url. openConnection ();
con. setDoInput (true);
con. setDoOutput (true);
con. setAllowUserInteraction (true);
con. setRequestProperty ("Connection", "keep-alive");
con. setRequestProperty ("Accept-Encoding", "gzip, deflate");
con. setRequestProperty ("Accept-Charset", "windows-1251, utf-8; q = 0.7, *; q = 0.7");
Con. setRequestProperty ("Referer", " www.orange.md/?c=5&sc=59 " );
con. setRequestProperty ("Accept", "text / html, application / xhtml + xml, application / xml; q = 0.9 ,*/*; q =0.8");
con. setRequestProperty ("Accept-Language", "ru, en-us; q = 0.7, en; q = 0.3");
con. setRequestProperty ("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; ru; rv: 1.8.1.12)Gecko/20080201 Firefox");
con. setRequestProperty ("Content-Type", "application / x-www-form-urlencoded; charset = utf-8");
con. setRequestProperty ("Pragma", "no-cache");
Pattern p = Pattern. Compile ("text / html; \ \ s + charset = ([^ \ \ s] +) \ \ s *");
Matcher m = p. matcher (con. getContentType ());
String charset = m. matches ()? M. group (1): "ISO-8859-1";
Reader r = new InputStreamReader (con. getInputStream (), charset);
StringBuilder buf = new StringBuilder ();
while (true) {
int ch = r. read ();
if (ch <0)
break;
buf. append ((char) ch);
}
String str = buf. ToString ();
int len = str. length ();
eventvalid = str. substring (3122, (len - 4540));
viewstate = str. substring (1496, (len - 4746));
temp = str. substring (6490, (len - 1240));
String headerValue = con. GetHeaderField (6) / / requested cookies (the number of cells found with the help of supplements for FireFix - HttpFox)
temp1 = headerValue. substring (0, (len1 - 17)) / / little cut unnecessary data from the cookie.

Then I had to screen a capture an image that was generated randomly each time you request. I tried to get her, sent tezhe cookies that were sent to me at first session, she did let herself get.

URL1 = new URL URL (" www.orangetext.md/CaptchaImage.axd?guid = " + temp);
URLConnection con1 = url1. OpenConnection ();
con1. setRequestProperty ("Host", " www.orangetext.md " );
con1. setRequestProperty ("Referer", " www.orangetext.md/ " );
con1. setRequestProperty ("Accept", "image / png, image / *; q = 0.8 ,*/*; q = 0.5");
con1. setRequestProperty ("Cookie", temp1 + "lang = ro");
con1. setRequestProperty ("Accept-Encoding", "gzip, deflate");
con1. setRequestProperty ("Accept-Charset", "windows-1251, utf-8; q = 0.7, *; q = 0.7");
con1. setRequestProperty ("Accept-Language", "ru, en-us; q = 0.7, en; q = 0.3");
con1. setRequestProperty ("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; ru; rv: 1.8.1.12)Gecko/20080201 Firefox");
con1. setRequestProperty ("Content-Type", "application / x-www-form-urlencoded; charset = utf-8");
con1. setRequestProperty ("Pragma", "no-cache");
con1. connect ();

Immediately after that I show it through ImageView.

InputStream is = (InputStream) con1. GetContent ();
Drawable d1 = Drawable. CreateFromStream (is, "src name");
imgView. setImageDrawable (d1);

The case remained for sending a POST request. I hung the whole thing on the button. Been looking for, how to pull the text out of Edith Box, was simply nowhere. The example below.

sendSMS. setOnClickListener (new Button. OnClickListener () {
public void onClick (View v)
{
try {

data + = "&" + URLEncoder. encode ("__VIEWSTATE", "UTF-8") + "=" + URLEncoder. encode (viewstate, "UTF-8");
data + = "&" + URLEncoder. encode ("__EVENTVALIDATION", "UTF-8") + "=" + URLEncoder. encode (eventvalid,"UTF-8");

data + = "&" + URLEncoder. encode ("btnOK", "UTF-8") + "=" + URLEncoder. encode ("trimite sms", "UTF-8");

By opening a new connection by sending the server through setRequestProperty () my old cookies, I made a POST request and simultaneously loads the page, so you can see off a SMS, or not.

OutputStreamWriter wr = new OutputStreamWriter (con3. getOutputStream ());
wr. write (data);
wr. flush ();
Pattern p1 = Pattern. Compile ("text / html; \ \ s + charset = ([^ \ \ s] +) \ \ s *");
Matcher m1 = p1. Matcher (con3. getContentType ());
String charset = m1. Matches ()? M1. Group (1): "ISO-8859-1";
Reader r1 = new InputStreamReader (con3. getInputStream (), charset);
StringBuilder buf1 = new StringBuilder ();
while (true) {
int ch1 = r1. read ();
if (ch1 <0)
break;
buf1. append ((char) ch1);
}
String str5 = buf1. ToString ();

Page always static, and change it to just one sentence, depending on the action. First, it is - success, the second - the error Captcha, and the third - exceeded the allowable number of SMS. To find out what happened at my end and put it on the screen, I decided simply to look at html-f only one word, which is only a proposal. If it met there, I decided to print a message in the initial TextView.

int intIndex = str6. indexOf ("succes");
int intIndex1 = str6. indexOf ("depasit");
int intIndex2 = str6. indexOf ("incorect");
if (intIndex == - 1) {} else {
io. setText ("Message was sent successfully.");
}
if (intIndex1 == - 1) {} else {
io. setText ("You sent more than five messages.");
}
if (intIndex2 == - 1) {} else {
io. setText ("You entered the wrong code in the image.");
}

Unpleasant surprise for me was that it does not work. It turned out it in the constraints that need to register in the file AndroidManifest, which I did, giving the program full access to the Internet.

uses - permission android: name = "android.permission.INTERNET"> </ uses - permission>

Epilogue

For me, the first application for the android was the gateway to the mobile programming. I was extremely delighted that this is the exact same java without limitation, wrapped in beautiful packaging. For those wishing to spread the sources. Download. zip download. apk

Android. Working with a status line.

2011-09-30T09:57:00.000-07:00

The article tells about how to deal with the status bar in Android. This article is intended for beginners only studying for the Android platform under development. Also worth noting that the status bar is more used to notify the user of any events occurring in a system that unites its target with pop-up notifications Toast. On Habrahabr already has a fairly complete article on using Toast, and this post only develops the theme of the notifications.

The text itself was written articles for the sandbox, and in fact Hello world as it is. Now I'm interested in wondering whether anyone at all, or a direction, or it's not worth it.

A brief notice about the line

In the first screenshot shows the status bar is disclosed in a standard envelope Android (some manufacturers of mobile devices in their shells can change its appearance, though the essence remains the same). The status bar in the Android is mostly used to notify the user of any events occurring in the system, as well as on the outcome of any applications. The essential difference from the pop-up notifications Toast is that the notification in the status bar does not disappear after a while, and "hang" there until the user somehow they react. Status bar is useful to receive notifications from applications running in the background, as well as with the emergence of a notification, you can play any sound, vibration, or use the flashing LED on the device (if any). The notification submitted by the screenshot - is exactly what we are today and will work.

Create a simple notification on the status bar

For a start try to create a standard disclaimer to the command line as it is recommended by Google. The layout of the application interface remain unchanged (notice to appear immediately after you start it). And so, the sample code (with commentary of what is possible may not be clear):

public class NotificationBar extends Activity { /** Called when the activity is first created. */ private static final int NOTIFY_ID = 1; // Уникальный индификатор вашего уведомления в пределах класса @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE); // Создаем экземпляр менеджера уведомлений int icon = android.R.drawable.sym_action_email; // Иконка для уведомления, я решил воспользоваться стандартной иконкой для Email CharSequence tickerText = "Hello Habrahabr" ; // Подробнее под кодом long when = System.currentTimeMillis(); // Выясним системное время Notification notification = new Notification(icon, tickerText, when); // Создаем экземпляр уведомления, и передаем ему наши параметры Context context = getApplicationContext(); CharSequence contentTitle = "Habrahabr" ; // Текст заголовка уведомления при развернутой строке статуса CharSequence contentText = "Пример простого уведомления" ; //Текст под заголовком уведомления при развернутой строке статуса Intent notificationIntent = new Intent( this , NotificationBar. class ); // Создаем экземпляр Intent PendingIntent contentIntent = PendingIntent.getActivity( this , 0, notificationIntent, 0); class ); // Подробное описание в UPD к статье notification.setLatestEventInfo(context, contentTitle, contentText, contentIntent); // Передаем в наше уведомление параметры вида при развернутой строке состояния mNotificationManager.notify(NOTIFY_ID, notification); // И наконец показываем наше уведомление через менеджер передав его ID } }
* This source code with WAS Highlighted Source Code Highlighter .

CharSequence tickerText = «Hello Habrahabr»; - in this line, we specify the text to be displayed in the minimized status bar for a few seconds with the appearance notice. After a few seconds it will disappear, and the line will only icon.

That's probably it. You can open the champagne, and watch what we have.

Create an advanced notification in the status bar

Now a few complicate the task - we will create a notification is not a pattern that suggests Google, but on its own markup (since there is such a possibility). And so we create a new markup file in the folder layout, you should get it like this:

< LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android" android:orientation ="horizontal" android:layout_width ="fill_parent" android:layout_height ="fill_parent" android:padding ="3dp" > < ImageView android:id ="@+id/image" android:layout_width ="wrap_content" android:layout_height ="fill_parent" android:layout_marginRight ="10dp" /> < TextView android:id ="@+id/text" android:layout_width ="wrap_content" android:layout_height ="fill_parent" android:textColor ="#000" /> </ LinearLayout > * This source code was highlighted with Source Code Highlighter .

Also add any folder or image in drawable so then set it to ImageView.

Now the code. The code is not very different from the code, a simple notice, but nevertheless requires comment

public class NotificationBar extends Activity { /** Called when the activity is first created. */ private static final int NOTIFY_ID = 1; // Уникальный индификатор вашего уведомления в пределах класса @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE); // Создаем экземпляр менеджера уведомлений int icon = android.R.drawable.sym_action_email; // Иконка для уведомления, я решил воспользоваться стандартной иконкой для Email CharSequence tickerText = "Hello Habrahabr" ; // Подробнее под кодом long when = System.currentTimeMillis(); // Выясним системное время Intent notificationIntent = new Intent( this , NotificationBar. class ); // Создаем экземпляр Intent Notification notification = new Notification(icon, tickerText, when); // Создаем экземпляр уведомления, и передаем ему наши параметры PendingIntent contentIntent = PendingIntent.getActivity( this , 0, notificationIntent, 0); // Подробное описание смотреть в UPD к статье RemoteViews contentView = new RemoteViews(getPackageName(), R.layout.notlayout); // Создаем экземпляр RemoteViews указывая использовать разметку нашего уведомления contentView.setImageViewResource(R.id.image, R.drawable.habr); // Привязываем нашу картинку к ImageView в разметке уведомления contentView.setTextViewText(R.id.text, "Привет Habrahabr! А мы тут, плюшками балуемся..." ); // Привязываем текст к TextView в нашей разметке notification.contentIntent = contentIntent; // Присваиваем contentIntent нашему уведомлению notification.contentView = contentView; // Присваиваем contentView нашему уведомлению mNotificationManager.notify(NOTIFY_ID, notification); // Выводим уведомление в строку } } * This source code was highlighted with Source Code Highlighter .

As a result, we can open a second bottle, and observe about this picture:

Adding sound and vibration, blinking.

For good measure, add the importance of sound in the derivation of the notification and vibration. Make it's not hard.

notification.defaults | = Notification.DEFAULT_SOUND; - this line sets the notification sound that is used by default.
notification.sound = Uri.parse («file: / / / sdcard/notification/ringer.mp3»); - this way you can install the sound from a file on your SD card.

notification.defaults | = Notification.DEFAULT_VIBRATE; - this adds a vibration in the Number of time by default.

In addition it is possible to set the time of vibration of their own. This is done in two lines
long [] vibrate = {0,100,200,300}; - create a file in which the first number - the time that you should wait before you start the vibration. The second meaning - the first vibration in milliseconds (the same, and 3, and 4 value). Amount of vibration may be infinitely large at the discretion of the programmer.
notification.vibrate = vibrate; - assign the array to our notice.

notification.defaults | = Notification.DEFAULT_LIGHTS; - this string we can blink with the default settings.

Of course, you can configure and ruchnuyu.Dlya this, we need four lines:
notification.ledARGB = 0xff00ff00; - sets the color for the RGB LED.
notification.ledOnMS = 300 - sets the time between blinks
notification.ledOffMS = 1000 - sets the time after which the indicator will extinguish burning
notification.flags | = Notification.FLAG_SHOW_LIGHTS; - allow flash
Here it should be noted that not all devices in general, there are any indicators.

Naturally, all these settings must be done before a line call notice.

Conclusion

That's probably it. Fasting does not purport to, and yet this information should be enough for beginners. As a source, as well as a more complete description of the work with NotificationBar can bring the original article ondeveloper.android.com . I hope someone can help, or article in the study of the platform. Thank you for your attention.

UPD: on closer examination it turned out that the comment to one of the missing lines of code (a code promises to explain, but most explanations there). Annoying bug fixes, as well as a number of faculty and a status bar that I forgot to inform the user fills DjVu , you can look in the comments: 1 , 2 . On the existence of serious pitfalls reports sdmitry 's here .

Interaction with the touch screen

2011-09-30T09:50:00.000-07:00

Catching up on programming for Android need to know how to interact with a touchscreen - the main input device for most of the Android devices. This article will be considered:

Low-level interaction with the touch screen, right above all for game development.
- Class MotionEvent
- Processing MotionEvent'ov
Working with MultiTouch.
Some high-touch processing techniques.

There will also be shown various examples of ...

The retreat over the Valley

Since later in this article, we will actively use the Log, I will briefly tell you about it (those who are already familiar with log Android may safely skip this section of the article).
In Android has its own log, which can write applications from all interested Dvalvik VM to your application. All messages in the log are separated by priority (right to choose the priority of the message is sent to the log is up to you)
To write to the log enough to cause one of the static class methods Log, differing only in priority sent by their messages.
These methods are listed below in ascending order of priority:

Log.v (String tag, String msg) - VERBOSE
Log.d (String tag, String msg) - DEBUG
Log.i (String tag, String msg) - INFO
Log.w (String tag, String msg) - WARNING
Log.e (String tag, String msg) - ERROR
Log.wtf (String tag, String msg) - What a Terrible Failure

It is also possible to send the log exceptions. In this case adds one more argument - Throwable tr. For example:

Log.v (String tag, String msg, Throwable tr)

Print the Log's window in Eclipse can be as follows:
Window -> Show View -> Other -> Android -> LogCat

The concept of MotionEvent

MotionEvent class serves as a repository of data on a touch (touch event). Each time a user spends with his finger on the screen, or even just Tapa, created an entire sequence of instances MotionEvent: sequence starts when a user touches the screen, continues until the user moves a finger across the screen and ends when the user lifts his finger. Thus there are three main types of action that describes MotionEvent: lowering the finger, his movement and uplift. Each MotionEvent keeps information about the type of action, which he describes. To this end, the class provides constant MotionEvent:

int MotionEvent.ACTION_DOWN - user puts his finger on the screen.
int MotionEvent.ACTION_MOVE - the user moves a finger across the screen.
int MotionEvent.ACTION_UP - user lifts the finger from the screen.

Learn what effect this describes MotionEvent by using the method getAction ().
It is worth noting that there is another type of action - MotionEvent.ACTION_CANCEL, which is essentially a symbol of what the sequence is completed correctly, then there is no MotionEvent.ACTION_UP. All of this will be explained in more detail the example, but a little later.

Receiving and processing of MotionEvents

Now that we've got a general idea of MotionEvent'ah must deal with the fact from us their "take." There are 2 ways, let us discuss them separately.

The first method is best when you use one of the standard View. In the View class has a method SetOnTouchListener (View.OnTouchListener l), an argument which is the class that implements the interface OnTouchListener. This method allows you to appoint a "listener" MotionEvent'ov. Interface OnTouchListener commits a class to implement the method public boolean OnTouch (View v, MotionEvent event), the second argument is that you want us to MotionEvent. Now every time the user will touch the screen, Android will call our method OnTouch, giving him a description of what happened in the argument of that is MotionEvent. Let us consider an example:
Here's our file res / layout / main.xml:

1 <? Xml version = "1.0" encoding = "utf-8"?>
2 <LinearLayout xmlns: android = " schemas.android.com / apk / res / android "
3 android: orientation = "vertical"
4 android: layout_width = "fill_parent"
5 android: layout_height = "fill_parent"
6 android: id = "@ + id / ll"
7>
8 </ LinearLayout>

But our class Activity:

An import android.app.Activity;
2 import android.os.Bundle;
3 import android.util.Log;
4 import android.view.MotionEvent;
5 import android.view.View;
6 import android.view.View.OnTouchListener;
7 import android.widget.LinearLayout;
8
9 public class main extends Activity implements OnTouchListener {/ / makes our class to translate the interface Activity OnTouchListener
10 / ** Called when the activity is first created. * /
11 @ Override
12 public void onCreate (Bundle savedInstanceState) {
13 super. OnCreate (savedInstanceState);
14 setContentView (R.layout.main);
15 LinearLayout ll = (LinearLayout) this. FindViewById (R.id.ll); / / We get the desired View
16 ll.setOnTouchListener (this); / / Set the class as a listener for our MotionEvent'ov LinearLayout
17}
18
19 @ Override
20 public boolean onTouch (View v, MotionEvent event) / / That's the method that will handle and MotionEvent'y.
21 {
22 int Action = event.getAction ();
23 / / The method getAction () Gets the type of action (ACTION_DOWN, ACTION_MOVE or ACTION_UP)
24 StringBuilder str = new StringBuilder ();
25 str.append ("\ nActrion type:");
26 / / Next for better (as a constant ACTION_DOWN, ACTION_MOVE ACTION_UP and numeric)
27 / / hold switch on the variable Action, and add to our StringBuilder name of the constant
28 switch (Action)
29 {
30 case MotionEvent.ACTION_DOWN: str.append («ACTION_DOWN \ n»); break;
31 case MotionEvent.ACTION_MOVE: str.append («ACTION_MOVE \ n»); break;
32 case MotionEvent.ACTION_UP: str.append («ACTION_UP \ n»); break;
33}
34 / / Use the methods getX () and getY () to obtain the coordinates x and y axes, respectively
35 / / It should be noted that the point 0 is located in the upper left corner of the screen.
36 / / x axis pointing to the right
37 / / y axis pointing down (the lower, the greater the coordinate).
38 str.append («Location:»). Append (event.getX ()). Append ("x"). Append (event.getY ()). Append ("\ n"); / / Learn coordinates
39 str.append («Edge flags:»). Append (event.getEdgeFlags ()). Append ("\ n"); / / method returns information about getEdgeFlags crossing edges of the screen
40 str.append («Pressure:»). Append (event.getPressure ()). Append ("\ n"); / / Learn pressure
41 str.append («Size:»). Append (event.getSize ()). Append ("\ n"); / / Learn the pointer size (places a finger on the touch screen)
42 str.append («Down time:»). Append (event.getDownTime ()). Append («ms \ n»); / / find out the time when the finger was lowered onto the screen in milliseconds
43 str.append («Event time:»). Append (event.getEventTime ()). Append («ms»); / / check the current time (corresponding to the processed MotionEvent'u) in milliseconds
44 str.append ("Elapsed:"). Append (event.getEventTime ()-event.getDownTime ()); / / find out how much time has passed since the lowering of a finger, to the current MotionEvent'a
45 Log.v («Mytag», str.toString ()); / / In order to be able to monitor these activities, we write about them all the information in the log.
46 return true; / / Why do we return true will be discussed later
47}
48}

It is clear that one class can be a listener in several View. To consider this method takes an argument onTouch View.
The second way is best, when you write your View class, which must respond to the touch. In View is a method onTouchEvent (MotionEvent event), which, actually, and can handle MotionEvent'y. Consider an example:
Write the class SomeView:

1 package com.example.MotionEventExample1;
2 import android.content.Context;
3 import android.util.AttributeSet;
4 import android.util.Log;
5 import android.view.MotionEvent;
6 import android.view.View;
7
8 public class SomeView extends View
9 {
10 / / First, you must implement a constructor.
11 / / It's simple - just call the superclass constructor
12 public SomeView (Context context, AttributeSet attrs)
13 {
14 super (context, attrs);
15}
16
17 / / Now proceed directly to processing MotionEvent'ov.
18 / / You need to rewrite the method onTouchEvent
19 @ Override
20 public boolean onTouchEvent (MotionEvent event)
21 {
22
23 Float X = (Float) event.getX ();
24 Float Y = (Float) event.getY ();
25 int Action = event.getAction ();
26 String ActionString = "";
27 switch (Action)
28 {
29 case MotionEvent.ACTION_DOWN: ActionString = «ACTION_DOWN»; break;
30 case MotionEvent.ACTION_MOVE: ActionString = «ACTION_MOVE»; break;
31 case MotionEvent.ACTION_UP: ActionString = «ACTION_UP»; break;
32}
33 Log.v («MyTag», «View OnTouchListener: \ n» + «Coords:» + X.toString () + "x" + Y.toString () + "\ nAction type:" + ActionString);
34 return true;
35}
36
37}
38

And our / res / layout / main.xml:

1 <? Xml version = "1.0" encoding = "utf-8"?>
2 <LinearLayout xmlns: android = " schemas.android.com / apk / res / android "
3 android: orientation = "vertical"
4 android: layout_width = "fill_parent"
5 android: layout_height = "fill_parent"
6>
7 <com.example.MotionEventExample1.SomeView
8 android: layout_width = "fill_parent"
9 android: layout_height = "fill_parent"
10 android: id = "@ + id / sv"
11 />
12 </ LinearLayout>
13

Activity class:
1 package com.example.MotionEventExample1;
An import android.app.Activity;
2 import android.os.Bundle;
3
4 public class main extends Activity {
5 / ** Called when the activity is first created. * /
6 @ Override
7 public void onCreate (Bundle savedInstanceState) {
8 super. OnCreate (savedInstanceState);
9 setContentView (R.layout.main);
10}
11}

The fact that the return handlers MotionEvent

As you can see, handlers must return MotionEvent's boolean value. In the examples before, we just always return true. So what do these methods must return a value? The fact that one View can be multiple listeners (eg onTouchEvent in the View and the outer OnTouch listener) and they have some precedence: OnTouch called first (if any), and after it can be called onTouchEvent. Call next on the priority of the handler just returned depends on the current value of the handler (true - there is nothing called, false - called the next priority, if any). Thus, Android allows us to share responsibility for handling touch on a few event'ov listeners.

Drag and Drop

So we figured out the basics of handling MotionEvento'ov. To consolidate the skills we write an application that implements a simple Drag and Drop.

Here is our / res / layout / main.xml:

1 <? Xml version = "1.0" encoding = "utf-8"?>
2 <LinearLayout xmlns: android = " schemas.android.com / apk / res / android "
3 android: orientation = "vertical"
4 android: layout_width = "fill_parent"
5 android: layout_height = "fill_parent"
6>
7 <com.example.dragdrop.SomeView
8 android: layout_width = "fill_parent"
9 android: layout_height = "fill_parent"
10 android: id = "@ + id / sv"
11 />
12 </ LinearLayout>

Here is our class Activity:

1 package com.example.dragdrop;
2
3 import android.app.Activity;
4 import android.os.Bundle;
5
6 public class main extends Activity {
7 / ** Called when the activity is first created. * /
8 @ Override
9 public void onCreate (Bundle savedInstanceState) {
10 super. OnCreate (savedInstanceState);
11 setContentView (R.layout.main);
12}
13}

But our main class SomeView:

1 package com.example.dragdrop;
2
3 import android.content.Context;
4 import android.graphics.Canvas;
5 import android.graphics.Color;
6 import android.graphics.Paint;
7 import android.graphics.Paint.Style;
8 import android.util.AttributeSet;
9 import android.view.MotionEvent;
10 import android.view.View;
11
12 public class SomeView extends View
13 {
14 Paint paint;
15 int X;
16 int Y;
17 final static int Radius = 20;
18 public SomeView (Context context, AttributeSet attrs)
19 {
20 super (context, attrs);
21 paint = new Paint ();
22 paint.setColor (Color.YELLOW);
23 paint.setStyle (Style.FILL);
24 X = 30;
25 Y = 30;
26}
27 @ Override
28 public boolean onTouchEvent (MotionEvent event)
29 {
30 X = (int) event.getX ();
31 Y = (int) event.getY ();
32 return true;
33}
34
35 @ Override
36 protected void onDraw (Canvas canvas) / / OnDraw method offered to Android when it needs to draw this View
37 {
38 canvas.drawCircle (X, Y, Radius, paint);
39 invalidate (); / / invalidate () is needed in order to alert the Android, you have to execute a method OnDraw again, without the View will not be perericovyvatsya.
40}
41
42}

Multitouch

In Android, how much would you finger-not used, information on all of them stored in one MotionEvent'e. The first method that you want to know if you intend to use multi - getPointerCount (), which returns the number of fingers, fixed on the screen (not always coincide with the actual number due to limitations in hardware). Each finger on the screen, given the index, and id. Indexes always start at 0, id - not necessarily. For clarity let us consider an example.
The first finger down - it is assigned index = 0 id = 0
The second finger down - it is assigned index = 1 and id = 1
The first finger raised - the second finger is assigned index = 0 (indices always start at zero), and id is the same
The second finger up - MotionEvent'ov no more, until the Next touch.
Id always reserved for a pointer (finger), so that we can always keep track of what you want the pointer.
When we have finished with the id and the indices, we consider how to get the properties (position, size, etc.) at a specific index, where many of them. To do this in class MotionEvent methods exist:

getX (int Index)
getY (int Index)
getSize (int Index)

and so on, we have considered them
In the argument of these methods take a pointer to the index.
But as the index pointer can vary, but often you want to track a specific finger, there is a very important method getPointerId (int index), which allows you to find the specified index id pointer.

Consider this example: rewrite our application (Drag and Drop) so that it viewed the multi-touch.
(Note: In multi-emulator does not verify, it can only be done on this devayse)
Here is our res / layout / main.xml
1 <? Xml version = "1.0" encoding = "utf-8"?>
2 <LinearLayout xmlns: android = " schemas.android.com / apk / res / android "
3 android: orientation = "vertical"
4 android: layout_width = "fill_parent"
5 android: layout_height = "fill_parent"
6>
7 <com.example.multitouch.SomeView
8 android: layout_width = "fill_parent"
9 android: layout_height = "wrap_content"
10 android: id = "@ + id / view"
11 />
12 </ LinearLayout>
13
Our Activity class:

1 package com.example.multitouch;
2
3 import android.app.Activity;
4 import android.os.Bundle;
5
6 public class main extends Activity {
7 / ** Called when the activity is first created. * /
8 @ Override
9 public void onCreate (Bundle savedInstanceState) {
10 super. OnCreate (savedInstanceState);
11 setContentView (R.layout.main);
12}
13}

But the main class - SomeView:
1 package com.example.multitouch;
2
3 import android.content.Context;
4 import android.graphics.Canvas;
5 import android.graphics.Color;
6 import android.graphics.Paint;
7 import android.graphics.Paint.Style;
8 import android.util.AttributeSet;
9 import android.util.Log;
10 import android.view.MotionEvent;
11 import android.view.View;
12
13 / / We draw the yellow circles under your fingers
14 public class SomeView extends View
15 {
16 Paint paint; / / need to set the color.
17 int [] X;
18 int [] Y;
19 final static int Radius = 20;
20 int PointerCount;
21 public SomeView (Context context, AttributeSet attrs)
22 {
23 super (context, attrs);
24 paint = new Paint ();
25 paint.setColor (Color.YELLOW);
26 paint.setStyle (Style.FILL);
27 PointerCount = 0;
28 X = new int [10] / / This will be the arrays of coordinates (we will take up to 10 fingers)
29 Y = new int [10];
30}
31 @ Override
32 public boolean onTouchEvent (MotionEvent event)
33 {
34 StringBuilder result = new StringBuilder (300);
35 PointerCount = event.getPointerCount ();
36 for (int i = 0; i <PointerCount; i + +)
37 {
38 int ptrId = event.getPointerId (i);
39 X [i] = (int) event.getX (i); / / Store the coordinates
40 Y [i] = (int) event.getY (i);
41 result.append («Pointer Index:»). Append (i);
42 result.append (", Pointer Id:"). Append (ptrId). Append ("\ n");
43 result.append («Location:»). Append (event.getX (i));
44 result.append ("x"). Append (event.getX (i)). Append ("\ n");
45 result.append («Pressure:»). Append (event.getPressure (i));
46 result.append («Size:»). Append (event.getSize (i)). Append ("\ n");
47}
48 Log.v («Mytag», result.toString ()); / / Output all the information in the log
49 return true;
50}
51
52 @ Override
53 protected void onDraw (Canvas canvas)
54 {
55 for (int i = 0; i <PointerCount; i + +) / / look how many fingers were on the screen and draw the View
56 {
57 canvas.drawCircle (X [i], Y [i], Radius, paint);
58}
59 invalidate (); / / invalidate () is needed in order to alert the Android, you have to execute a method OnDraw again, without the View will not be pereriovyvatsya.
60}
61
62}
63

Other ways to interact with touchscreen

Interaction with the screen is quite a low level MotionEvent'y need it primarily for game development. For more specific, everyday situations in the Android provides a number of interfaces that allow you to identify the most "popular» touch event'y:

OnClickListener - onClick (View v)
OnFocusChangeListener - onFocusChange (View v, boolean hasFocus)
OnKeyListener - onKey (View v, int keyCode, KeyEvent event)
OnLongClickListener - onLongClick (View v)

etc.

They are treated similarly, so that explanation does not need.
More information about these methods can be found here:
developer.android.com / reference / android / view / View.html

Used for this article:

developer.android.com
Pro Android 2 - Head TouchScreens.

Thank you for your attention.

Using Android Search Dialog. Recent Query Suggestions. (part 2)

2011-09-29T14:08:00.000-07:00

Article essential reading for those who mastered the first part . The article explains how to modify your application so that added to the dialogue hints at a recent search queries. To understand the code and theory (beyond what was required in the first part) requires knowledge of the content providers. It can be gleaned from official Gajda .

A bit of theory

In fact, hints of the recent searches are simply saved queries. When the user selects one of the tips, the Activity, which is responsible for search, type Search gets Intent with a hint of a line, it is already treated before. For displaying tooltips, as well as for the whole dialogue, responds Search Manager, and is used to store the content provider.

When the Search Manager determines our Activity as responsible for finding and providing clues to the search, the following sequence of actions occurs:

When the Search Manager receives the search request, it sends a request to the content provider, provides tips.
Content provider returns a cursor that points to clues that coincide with the text search.
Search Manager displays a prompt, using the cursor

Once a list of tips has been mapped, it may be the following:

If the user changes the text of the query, then all of the above steps are repeated.
If the user starts the search, the hints are ignored.
If the user selects a clue what to Activity Intent is delivered with the text that prompts the query.

So, to implement the tips we need the following:

Create a content provider, which will inherit from SearchRecentSuggestionsProvider and declare it in the manifesto
Change the configuration xml file dialog to add the information about the content provider
Change Activty so that it retained searches every time we run search

Create a content provider

All we need is a content provider that inherits SearchRecentSuggestionsProvider . This class makes for virtually all of the developer and all that is required of us - is to write a constructor.

File SuggestionProvider.java

package com.example.search; import android.content.SearchRecentSuggestionsProvider; public class SuggestionProvider extends SearchRecentSuggestionsProvider { public final static String AUTHORITY = "com.example.search.SuggestionProvider" ; public final static int MODE = DATABASE_MODE_QUERIES; public SuggestionProvider() { setupSuggestions(AUTHORITY, MODE); } } * This source code was highlighted with Source Code Highlighter .

Method setupSuggestions () takes a string and the authorization mode of the database content provider. The string can be any authorization, the only requirement - is unique. However, official documentation is recommended to use the full name of the content provider, including the name of the package. Mode database should include DATABASE_MODE_QUERIES , and optionally you can add DATABASE_MODE_2LINES . In the second case to the table hint is added to the column that allows you to display hints for each of the second row. Look in the code is as follows:

public final static int MODE = DATABASE_MODE_QUERIES | DATABASE_MODE_2LINES; * This source code was highlighted with Source Code Highlighter .

Now do not forget that you must declare our content provider in the manifest.

File AndroidManifest.xml

<? xml version ="1.0" encoding ="utf-8" ? > < manifest xmlns:android ="http://schemas.android.com/apk/res/android" package ="com.example.search" android:versionCode ="1" android:versionName ="1.0" > < application android:icon ="@drawable/icon" android:label ="@string/app_name" > < activity android:name =".Main" android:label ="@string/app_name" > < intent-filter > < action android:name ="android.intent.action.MAIN" /> < category android:name ="android.intent.category.LAUNCHER" /> </ intent-filter > < intent-filter > < action android:name ="android.intent.action.SEARCH" /> </ intent-filter > < meta-data android:name ="android.app.searchable" android:resource ="@xml/searchable" /> </ activity > < provider android:name =".SuggestionProvider" android:authorities ="com.example.search.SuggestionProvider" /> </ application > < uses-sdk android:minSdkVersion ="5" /> </ manifest > * This source code was highlighted with Source Code Highlighter .

Changing the configuration file

To use our dialogue content provider for tips to add to his options android: searchSuggestAuthority and android: searchSuggestSelection

File searchable.xml

<? xml version ="1.0" encoding ="utf-8" ? > < searchable xmlns:android ="http://schemas.android.com/apk/res/android" android:label ="@string/app_name" android:hint ="@string/search_hint" android:searchSuggestAuthority ="com.example.search.SuggestionProvider" android:searchSuggestSelection =" ?" > </ searchable > * This source code was highlighted with Source Code Highlighter .

The value of android: searchSuggestAuthority must exactly match the string authorize the content provider.
The value of android: searchSuggestSelection must be a question mark placed after a space, because this is an argument from a sample database and the question mark is automatically replaced with the text typed by the user.

Change Activity

All we need - is to save the query text for this class is instantiated SearchRecentSuggestions and callssaveRecentQuery () . This happens every time the Activity Intent comes with a request for search data. In the method saveRecentQuery () takes two parameters, the first is mandatory and is a string search query, the second - optional, required if you use DATABASE_MODE_2LINES to display the second line of text on the tooltip.

The official documentation is also recommended to provide an interface for clearing the entire table hints.Apparently, it is necessary to ensure user's privacy. We just add another menu item, when clicked, will be called clearing the entire history of requests.

File Main.java

package com.example.search; import android.app.ListActivity; import android.app.SearchManager; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.provider.SearchRecentSuggestions; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.SimpleCursorAdapter; public class Main extends ListActivity { private EditText text; private Button add; private RecordsDbHelper mDbHelper; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); //Создаем экземпляр БД mDbHelper = new RecordsDbHelper( this ); //Открываем БД для записи mDbHelper.open(); //Получаем Intent Intent intent = getIntent(); //Проверяем тип Intent if (Intent.ACTION_SEARCH.equals(intent.getAction())) { //Берем строку запроса из экстры String query = intent.getStringExtra(SearchManager.QUERY); //Создаем экземпляр SearchRecentSuggestions SearchRecentSuggestions suggestions = new SearchRecentSuggestions( this , SuggestionProvider.AUTHORITY, SuggestionProvider.MODE); //Сохраняем запрос suggestions.saveRecentQuery(query, null ); //Выполняем поиск showResults(query); } add = (Button) findViewById(R.id.add); text = (EditText) findViewById(R.id.text); add.setOnClickListener( new View.OnClickListener() { public void onClick(View view) { String data = text.getText().toString(); if (!data.equals( "" )) { saveTask(data); text.setText( "" ); } } }); } private void saveTask( String data) { mDbHelper.createRecord(data); } private void showResults( String query) { //Ищем совпадения Cursor cursor = mDbHelper.fetchRecordsByQuery(query); startManagingCursor(cursor); String [] from = new String [] { RecordsDbHelper.KEY_DATA }; int [] to = new int [] { R.id.text1 }; SimpleCursorAdapter records = new SimpleCursorAdapter( this , R.layout.record, cursor, from , to); //Обновляем адаптер setListAdapter(records); } //Создаем меню для вызова поиска (интерфейс в res/menu/main_menu.xml) public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.main_menu, menu); return true ; } public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.search_record: //Вызываем поиск onSearchRequested(); return true ; case R.id.clear_recent_suggestions: //Очищаем историю SearchRecentSuggestions suggestions = new SearchRecentSuggestions( this , SuggestionProvider.AUTHORITY, SuggestionProvider.MODE); suggestions.clearHistory(); return true ; default : return super.onOptionsItemSelected(item); } } } * This source code was highlighted with Source Code Highlighter .

Conclusion

This article used the documentation from developer.android.com
The entire project is modified to code.google.com

Using Android Search Dialog. A simple application (part 1)

2011-09-29T14:01:00.000-07:00

This article is for those who have already written the HelloWorld for Android, and know what the Activity and Intent, as well as where there is manifest, and why you need layout'y. Otherwise, you acquainted with this material, for example, developer.android.com .

The article describes how to create a simple application that uses a mechanism to implement the search capabilities built based on the framework. After reading, you can also configure your application so that it searches through the data using a standard Android Search Dialog.

A bit of theory

Android Search Dialog (hereinafter - the "search dialog") is controlled using a search framework. This means that the developer does not need to worry over how to paint or how to catch the search query. For this job you willSearchManager .

So, when a user starts searching, SearchManager creates Intent, and sends it to the Activity, which is responsible for searching for data (in this case the query is placed in the extras). That is, in fact in the application must have at least one Activity, which receives Intent'y search, searches, and provides the user with the results. To realize you need:

Xml configuration file (it contains information about the dialogue)
Activity, which will receive queries, perform searches and display the results on screen
The mechanism of calling the search dialog (since not all devices with Android on board are on the case of the search button)

The configuration file

Start by creating a configuration file, because it's the easy part. Of course, you need to prepare in advance, to create a new project, Activity (I used Activity «Main» and the name of the project «SearchExample»). All that is needed for the configuration - is to create a file in a subdirectory searchable.xml res / xml / your project, with the following content.

<? xml version ="1.0" encoding ="utf-8" ? > < searchable xmlns:android ="http://schemas.android.com/apk/res/android" android:label ="@string/app_name" android:hint ="@string/search_hint" > </ searchable > * This source code was highlighted with Source Code Highlighter .

Required attribute is only android: label, and it must refer to a string that is the same as the name of the application. The second attribute, android: hint is used to display an empty row in the dialog. For example, it might be "Search Videos" or "search contacts", etc. This attribute specifies which data to be searched. It is also important to know that the element searchable supports many other attributes, you can read more here .

Create an Activity

Minimally, all we need from the UI Activity - a list to display the search results and the mechanism of calling the search dialog. Let's do that by adding just the text field and button, so that we ourselves can fill the base.Looking ahead, I will say that the data will be stored in a database SQLite.

We describe the interface of Activity as follows (the file is in res / layout / main.xml).

<? xml version ="1.0" encoding ="utf-8" ? > < LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android" android:orientation ="vertical" android:layout_width ="fill_parent" android:layout_height ="fill_parent" > < LinearLayout android:orientation ="horizontal" android:layout_width ="fill_parent" android:layout_height ="wrap_content" android:gravity ="top" > < EditText android:id ="@+id/text" android:layout_width ="wrap_content" android:layout_height ="wrap_content" android:hint ="@string/text" android:layout_weight ="100.0" /> < Button android:id ="@+id/add" android:layout_width ="wrap_content" android:layout_height ="wrap_content" android:text ="@string/add" /> </ LinearLayout > < ListView android:id ="@android:id/list" android:layout_width ="fill_parent" android:layout_height ="wrap_content" /> < TextView android:layout_gravity ="left" android:id ="@android:id/empty" android:layout_width ="fill_parent" android:layout_height ="fill_parent" android:text ="@string/no_records" /> </ LinearLayout > * This source code was highlighted with Source Code Highlighter .

As follows:

We also need to layout the form of a list item, describe it in the simplest way (the file is in res / layout / record.xml)

<? xml version ="1.0" encoding ="utf-8" ? > < TextView android:id ="@+id/text1" xmlns:android ="http://schemas.android.com/apk/res/android" android:layout_width ="wrap_content" android:layout_height ="wrap_content" /> * This source code was highlighted with Source Code Highlighter .

Also, do not forget about the resource file that stores our string (a file in res / values / strings.xml)

<? xml version ="1.0" encoding ="utf-8" ? > < resources > < string name ="app_name" > SearchExample </ string > < string name ="add" > Add </ string > < string name ="text" > Enter text </ string > < string name ="no_records" > There are no records in the table </ string > < string name ="search_hint" > Search the records </ string > < string name ="search" > Search </ string > </ resources > * This source code was highlighted with Source Code Highlighter .

I recall that when the user performs a search, you need to send SearchManager Intent with the search query to our Activity. To SearchManager knew exactly where to send the Intent, must declare it in the manifest. So, go to AndroidManifest.xml, and change it so that it could take Activity type Intent'y Search. In addition, we apply our configuration file searchable.xml. Thus, the manifest will look something like this:

<? xml version ="1.0" encoding ="utf-8" ? > < manifest xmlns:android ="http://schemas.android.com/apk/res/android" package ="com.example.search" android:versionCode ="1" android:versionName ="1.0" > < application android:icon ="@drawable/icon" android:label ="@string/app_name" > < activity android:name =".Main" android:label ="@string/app_name" > < intent-filter > < action android:name ="android.intent.action.MAIN" /> < category android:name ="android.intent.category.LAUNCHER" /> </ intent-filter > < intent-filter > < action android:name ="android.intent.action.SEARCH" /> </ intent-filter > < meta-data android:name ="android.app.searchable" android:resource ="@xml/searchable" /> </ activity > </ application > < uses-sdk android:minSdkVersion ="5" /> </ manifest > * This source code was highlighted with Source Code Highlighter .

Now, you can now check that all you have done correctly. Call the dialogue on the emulator you can, for example, by pressing the search button. Well, or if you check on devayse, then holding down the "Menu". Should look like this:

Perform a search

After we announced our Activity and make the necessary changes in AndroidManifest.xml, we can consider itself doing a search. It includes three stages:

Receipt of an inquiry
Data Search
output results

Receipt of an inquiry

Since SearchManager sends Intent type Search our Activity, then all you need to do is check on the Intent of this type at the start of Activity. Then, if we get the desired Intent, then you can retrieve it from the extrusion, and search.

Data Search

Since the type of data storage structures for different applications can vary, the methods for them and theirs. In our case, the easiest way to query the database table query SQLite LIKE. Of course, it is better to use FTS3, it is much faster, more about FTS3 can be read on the site SQLite.org . Ideally, as one should always expect that the search may take a long time, so you can create some ProgressDialog, so we have not hung interface, and that the user knows that the application works.

Output results

In general, the output of the results - it is a problem UI, but since we use the ListView, then for us the problem is solved by simply updating the adapter.

Source

Finally, I cite the full source code of two classes with commentary. First - Main, heir ListActivity, it is used to populate the database and display the results. The second class - RecordsDbHelper, it implements an interface to interact with the database. The most important methods - add entries and search for matches, with a query LIKE.

File Main.java

package com.example.search; import android.app.ListActivity; import android.app.SearchManager; import android.content.Intent; import android.database.Cursor; import android.os.Bundle; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.SimpleCursorAdapter; public class Main extends ListActivity { private EditText text; private Button add; private RecordsDbHelper mDbHelper; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); //Создаем экземпляр БД mDbHelper = new RecordsDbHelper( this ); //Открываем БД для записи mDbHelper.open(); //Получаем Intent Intent intent = getIntent(); //Проверяем тип Intent if (Intent.ACTION_SEARCH.equals(intent.getAction())) { //Берем строку запроса из экстры String query = intent.getStringExtra(SearchManager.QUERY); //Выполняем поиск showResults(query); } add = (Button) findViewById(R.id.add); text = (EditText) findViewById(R.id.text); add.setOnClickListener( new View.OnClickListener() { public void onClick(View view) { String data = text.getText().toString(); if (!data.equals( "" )) { saveTask(data); text.setText( "" ); } } }); } private void saveTask( String data) { mDbHelper.createRecord(data); } private void showResults( String query) { //Ищем совпадения Cursor cursor = mDbHelper.fetchRecordsByQuery(query); startManagingCursor(cursor); String [] from = new String [] { RecordsDbHelper.KEY_DATA }; int [] to = new int [] { R.id.text1 }; SimpleCursorAdapter records = new SimpleCursorAdapter( this , R.layout.record, cursor, from , to); //Обновляем адаптер setListAdapter(records); } //Создаем меню для вызова поиска (интерфейс в res/menu/main_menu.xml) public boolean onCreateOptionsMenu(Menu menu) { MenuInflater inflater = getMenuInflater(); inflater.inflate(R.menu.main_menu, menu); return true ; } public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.search_record: onSearchRequested(); return true ; default : return super.onOptionsItemSelected(item); } } } * This source code was highlighted with Source Code Highlighter .

File RecordsDbHelper.java

package com.example.search; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; public class RecordsDbHelper { public static final String KEY_DATA = "data" ; public static final String KEY_ROWID = "_id" ; private static final String TAG = "RecordsDbHelper" ; private DatabaseHelper mDbHelper; private SQLiteDatabase mDb; private static final String DATABASE_CREATE = "CREATE TABLE records(_id INTEGER PRIMARY KEY AUTOINCREMENT, " + "data TEXT NOT NULL);" ; private static final String DATABASE_NAME = "data" ; private static final String DATABASE_TABLE = "records" ; private static final int DATABASE_VERSION = 1; private final Context mCtx; private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null , DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(DATABASE_CREATE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data" ); db.execSQL( "DROP TABLE IF EXISTS tasks" ); onCreate(db); } } public RecordsDbHelper(Context ctx) { this .mCtx = ctx; } public RecordsDbHelper open() throws SQLException { mDbHelper = new DatabaseHelper(mCtx); mDb = mDbHelper.getWritableDatabase(); return this ; } public void close() { mDbHelper.close(); } //Добавляем запись в таблицу public long createRecord( String data) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_DATA, data); return mDb.insert(DATABASE_TABLE, null , initialValues); } //Поиск запросом LIKE public Cursor fetchRecordsByQuery( String query) { return mDb.query( true , DATABASE_TABLE, new String [] { KEY_ROWID, KEY_DATA }, KEY_DATA + " LIKE" + "'%" + query + "%'" , null , null , null , null , null ); } } * This source code was highlighted with Source Code Highlighter .

Conclusion

Used for this article documents with developer.android.com
The whole project can take on code.google.com .

10 useful solutions for the Android Developer

2011-09-29T13:45:00.000-07:00

Content

Entry
About the adapters list ( ListView ) with subcategories (for grouping items in the list)
About the lists that contain any of the (list items do anything complicated or alter themselves for selection)
About forced invalidation of the lists
About caching images for ListView (for lists with images)
About adapters, iterates through the cursor (to support pagination on the list)
About authorization via OAuth to Android
About using MediaPlayer and bufferring video feed over HTTP
About the turn of a few AsyncTask (alternate to perform background tasks)
About changing illumination of the selected item in ListView
About adding QuickActions in project
Three more small solving

1. Entry

Last summer (already), I had a great desire to write a client for Android-web service Vimeo . I like this service, and as for me, it would be convenient to watch for updates in subscriptions to the video device.

I conceived this project for myself as an academic (in the sense that I'm learning), but the result was to make quite a tangible part (you can see screenshots of what is done ), but it has not yet been completed. This client does not just me, his version is almost the same time (he was the first) began to make me makotosan and his version so far, it seems, also has done).

In any case, the process of writing project, I gained some knowledge base, which I hasten to share. Not all threads exclusive, but some see the subtleties are not disclosed on the Internet or buried pretty deep in its bowels. I will give examples of additional codes iskhodnyh vimeoid, this will allow you podcmotret as the topic under consideration operates in real time (NB: some links lead to specific line in the code).

2. Lists with subcategories

Aside from the usual use of ListView , is often required to make a list in which items are grouped into several sections in the form header section, paragraph, item, item, ..., a section heading, paragraph, item, ..., a section heading, paragraph, point, and so on ... In the picture are sections «Statistics» and «Information».

(Hereafter I will use the word as an analogue to the English point item, to distinguish between a list item, which may be heading, and the point from point customary element, which can not be a title)

Headers should not react to clicks and the selection and must have their own kind. This can be achieved by redefining except getView method getItemViewType , getViewTypeCount and isEnabled adapter of this list and it otnasledovav, for example, BaseAdapter .

 public class SectionedItemsAdapter extends BaseAdapter {.  .  .

An example of vimeoid: SectionedActionsAdapter

Primarily infest constants that uniquely identify the item type, one for the header, the second for the item (that is, types may be greater than two, but in this case it is better to use the enum to a set of identifiers):

 public static final int ITEM_VIEW_TYPE = 0; \ \ item
 public static final int SECTION_VIEW_TYPE = 1 \ \ section

Then constant containing the number of types of elements (in our case - two):

 public static final int VIEW_TYPES_COUNT = SECTION_VIEW_TYPE + 1;

The adapter will contain information on all elements, so the implementation getCount , getItem and getItemIddepend on your situation.

Method getItemViewType should return the type of the constant element in his position. For an undetermined type of element in the class Adapter there is a constant IGNORE_ITEM_VIEW_TYPE .

 public int getItemViewType (int position) {
    if (...) return ITEM_VIEW_TYPE;
    if (...) return SECTION_VIEW_TYPE;
    return IGNORE_ITEM_VIEW_TYPE;
 }

In my case I keep the adapter list of sections that contain them owned items. Thus, each partition can be asked how many items within it at the cost of this to know the type.

This method can now be used to override the getView :

 public View getView (int position, View convertView, ViewGroup parent) {
     final int viewType = getItemViewType (position);
     if (viewType == IGNORE_ITEM_VIEW_TYPE) throw new IllegalStateException ("Failed to get object at position" + position);
     if (viewType == SECTION_VIEW_TYPE) { 
         convertView =.  .  .  / / Here you can get through LayoutInflater Layout for the section title
     } Else if (viewType == ITEM_VIEW_TYPE) {
         convertView =.  .  .  / / Here you can get through LayoutInflater Layout for the item
     }
     return convertView;    
 }

The method isEnabled should return false for the items that can not be pressed and that can not move the cursor, and true for others. Here, again, will getItemViewType :

 public boolean isEnabled (int position) { 
     return getItemViewType (position)! = SECTION_VIEW_TYPE};

Method getViewTypeCount returns the most constant, the number of possible types of elements:

 public int getViewTypeCount () {return VIEW_TYPES_COUNT;}

By the way, you can store a reference to LayoutInflater in the adapter and get it from that created it aktiviti through the constructor.

That's all you need to work with a list of sections, if necessary - look over here, but first give some explanations.

The example I use a structure for storing data of the sections and paragraphs. The structure of the partition is stored identifier section, its title and structure of the items contained therein. Structure keeps a pointer to point to the parent structure of the section heading, paragraph, the path to the icon and the click handler on the point (about it in the next chapter). The designers of both structures are available only for adapters:

An example of vimeoid: LActionItem

So I simplified the adding of groups and items in the list. The adapter has methods:

 public int addSection (String title);
 public LActionItem addItem (int section, int icon, String title);

Method addSection returns a group ID, which can then be used to add items to this group:

 final int suitsSection = adapter.addSection ("Suits");
 adapter.addItem (suitsSection, R.drawable.heart, "Hearts");
 adapter.addItem (suitsSection, R.drawable.diamond, "Diamonds");
 adapter.addItem (suitsSection, R.drawable.spade, "Spades");
 adapter.addItem (suitsSection, R.drawable.cross, "Crosses");
 final int figuresSection = adapter.addSection ("Figures");
 adapter.addItem (figuresSection, R.drawable.king, "King");
 adapter.addItem (figuresSection, R.drawable.queen, "Queen");
 .  .  .

3. Lists with responsive elements

Sometimes you need to when you click on the item list, it changed its status and / or switched aktiviti. For example, the "Follow" in the list of actions on account of Twitter may contain an icon with a minus, if you have not follovili this person and change the icon on the plus and come after you for confirmation of follovinge. You can handle the selected item in the current ListActivity and depending on the position to make a decision, but if the list is contained somewhere within the normal Activity , then perhaps the choice is easier to handle in the adapter.

An example of vimeoid: SectionedActionsAdapter
Uses: LActionItem
Used in: SingleItemActivity_

If you agree with that, your adapter can implement the interface OnItemClickListener :

 public class ActionsAdapter extends.  .  .  implements OnItemClickListener

And using it aktiviti you can do:

 final ListView actionsList = (ListView) findViewById (R.id.actionsList);
 final SectionedActionsAdapter actionsAdapter = new ActionsAdapter (...);
 .  .  .  / / Fill the adapter values
 actionsList.setAdapter (actionsAdapter);
 actionsList.setOnItemClickListener (actionsAdapter);

In my case, for points in each section serve some kind of action - go to aktiviti or change the view point of the request to the server. So I chose to make the structure of the publicly available properties for sections and paragraphs, and the structure of the items contain handler OnClick which takes View on which there was a choice, so you can change the View directly from them. Thanks to this adapter, you can simply pass the handler:

 public void onItemClick (AdapterView <?> parent, View view, int position, long id) {
     final LActionItem item = (LActionItem) getItem (position);
     if (item.onClick! = null) item.onClick (view);
 }

Using the above method addItem can install the handler:

 final LActionItem heartsItem = adapter.addItem (suitsSection, R.drawable.heart, "Hearts");
 heartsItem.onClick = new OnClickListener () {public void onClick (View view) {.  .  .  }};

4. Forced invalidation of the lists

ListView in Android, as we know, are arranged with the trick, this trick - ListView Recycler . Prinitsip Recycler'and, if briefly, is that if the list of items than fit on the screen as you scroll down the list of kinds of new elements are created and reused the old forms - in this implementation work prinitsipe getView in adapters.

If at some point need to upgrade (invalidirovat) The specific form of the element well-known (or even a child form) of the list at a time when it is visible on the screen, you can call ListView.invalidate() orAdapter.notifyDataSetChanged() , but sometimes these irrational methods update and neighboring species, if at all, all visible (especially if the layout is built correctly ). Is there a way to get the current form of a list item using the method ListView.getChildAt(position) . However, the position in this case is not an index entry in the list, as would be expected, and the index relative to visible on-screen forms. So useful are these methods:

 public static View getItemViewIfVisible (AdapterView <?> holder, int itemPos) {
     int firstPosition = holder.getFirstVisiblePosition ();
     int wantedChild = itemPos - firstPosition;
     if (wantedChild <0 | | wantedChild> = holder.getChildCount ()) return null;
     return holder.getChildAt (wantedChild);
 }

 public static void invalidateByPos (AdapterView <?> parent, int position) {
     final View itemView = getItemViewIfVisible (parent, position);
     if (itemView! = null) itemView.invalidate ();        
 }

invalidateByPos update form only if it is visible on the screen (by force causing getView adapter), and if the item does not see - getView adapter will be automatically called when the form appears in the sight when you scroll through the list. To update a child form of the element, you can use the getViewIsVisible , it will return the form element from which you can access its child types and null , if the view is not visible to the user and updating is not necessary.

Methods described in class: Utils

5. About caching images for lists

If you create a list of ListView , which contains an image downloaded from the network, this chapter is for you.It is unwise to be on every call getView adapter to get the image on the URL again - of course it would be better to a) cache b) request only if the form with the image visible to the user. At the moment this problem is so often the programmers would get up on Android, there is already a lot of her decisions .

My version from the same source, this solution Fedor Vlasov , corrected for my needs. First, I made a directory for storing cached images of static - that is, once it is created during the lifetime of the application and consistently clears the call clearCache (this method is useful to call in onDestroy() in aktiviti using ImageLoader orfinalize() for using it adapter), slightly changed the way the creation of this catalog (seeUtils.createCacheDir() ). Second, the designer can pass ids of images to be displayed on site Pictures in the process of downloading and / or download if it failed. In the third a couple of small changes. In general, this class could be done and Singleton, changing settings before using it, but it's up to you. In my case, one by one instance is created for each running ListActivity and passed to each adapter in need ListView (or created in the adapter itself, if the ListView is inside the regular Activity ). The basic method - displayImage(String url, ImageView view) , the definition speaks for itself.

Source of vimeoid: ImageLoader
Uses the methods of: Utils

6. Adapters, iterates through the cursors

This chapter deals with the pagination in the ListView . That is, the user sees the first n items, scrolls the list up to n -matrix element, and only after a request is made for the next n elements of the database or the server.Then, the user scrolls down the list until the element 2n , and we request the following pack sizes n , etc. Invimeoid I make the following query when you click on footerView that says "Load more ..." from the list: do not automatically, but the technique is roughly the same. </ p

Download by clicking on footerView : ItemsListActivity_
The implementation for the guest: ItemsListActivity
Implementation for registered users: ItemsListActivity

Here, a more complex hierarchy of classes, loading each page through a special AsyncTask , after which the background Vimeo API call informs the caller aktiviti, remained there still elements and not the last page whether it is, and aktiviti updates its forms in accordance with these data.

The adapter contains a set of cursors: EasyCursorsAdapter

In order to provide paged, you can just keep a list of the containers for pages (eg, cursor) in the adapter, and the getView() , if requested by one of the last items, run a query on the following page (preferably - AsyncTask ), which in receiving a new container will add it to the adapter and the adapter can cause notifyDataSetChanged() .Like this:

 private final Page [] pages = new Page [MAX_PAGES_COUNT];

 public View getView (final int position, View convertView, ViewGroup parent) {

     if (! waitingNextPage & & 
         (Pages.length <MAX_PAGES_COUNT) & & 
         (Position> = ((pages.length * PER_PAGE) - 2))) {

         final AsyncTask <Integer,.  .  .> NextPageTask =.  .  .;
         nextPageTask.execute (pages.length);
         / / NextPageTask is addSource, when it receives a new page

         waitingNextPage = true;
     } 

     .  .  .

 }

 public void addSource (Page page) {
    if (pages.length> = MAX_PAGES_COUNT) return; 
    pages [pages.length] = page;
    waitingNextPage = false;
    notifyDataSetChanged ();
 }

EasyCursorsAdapter - a good example, where as a counterpart to Page appears Cursor . Surely there are alternatives would be happy if they mentioned in the comments.

7. Sign in via OAuth to Android

If you write a client for any complex web service - you are confronted with the problem of authorization, the vast number of web services for its implementation now uses OAuth and Vimeo just among those.

It is not necessary to write the implementation itself is somewhat thankless task, since there is already a great library signpost and better alternatives as far as I know, yet.

An example of vimeoid: VimeoApi
Uses a signpost: JsonOverHttp
Aktiviti that receives user token: ReceiveCredentials
His description on the manifest: AndroidManifest.xml

First you need to get a unique key for your application from a Web service and specify the Web service URL, which will vozvraschatsya user when authorization is successful (eg, vimeoid://oauth.done ) (but in the case of Android it pass when asked to /request_token ). Usually this is done via the web interface of the service.

The algorithm first authorization to Android is the following:

Specify the signpost where the service entry points are located in OAuth
Request to /request_token get a couple of token / secret annex for unauthorized requests for this key (kolbek-URL vimeoid://oauth.done pass here): provider.retrieveRequestToken(Uri callbackUri) . NB:retrieveRequestToken not return a token, and immediately Uri , same authUri by which we must turn to next paragraph
Aktiviti run a browser, go to /authorize , by passing a token application and, if necessary, adding additional parameters to the required rights: startActivity(new Intent(Intent.ACTION_VIEW, authUri + ...))
The user will see the page in the style of "Allow this application to access your account?" (When he logged out of service, he will offer to login). If it allows access, the browser is redirected to the address kolbeka vimeoid://oauth.done?... , but since your AndroidManifest.xml to capture such a special URL described aktiviti, Android user returns to your application, it is the opening aktiviti - ReceiveCredentials
In aktiviti ReceiveCredentials you get the user token in the parameters of Uri uri = getIntent().getData() , now on the token to obtain the secret through a request to /access_token :provider.retrieveAccessToken(Uri uri)
Now you can save the token and secret user, for example, in private SharedPreferences :consumer.getToken() , consumer.getTokenSecret()

You can then sign each request to Web Service API token obtained: consumer.sign(Object request) . If your application has been restarted, before any requests can be checked if there are any tokens SharedPreferences , if there is - to remind them signpost 'in: consumer.setTokenWithSecret(String token, String secret) , and if not - ask the secret user again (or refresh tokens, if the Web service allows it).

Important note: on Android signpost works only with CommonsHttpOAuthConsumer / CommonsHttpOAuthProvider .Classes DefaultOAuth* do not work.

8. Media Player buffering and video via HTTP

MediaPlayer as it turned out, it is very difficult to get to work just as you want, when playing videos. To get the video I had to perform an unusual request from the HTTP-specific headers, so getting the stream and had to write by hand bufferizirovanie. Streaming on analogue samples for audio files , I did not work, so for now I just load the video completely and start playing when it is already loaded (if your card is not enough space, I warn the user). When you close the player or playing I failed to clear the cache.

Still, the behavior VideoView / SurfaceView switching within a single species leyauta also works very mixed (black screen every other time), so we had to leave in the layout banal single VideoView and show ProgressDialog over him while the video loads. Again, if you know something about the streaming video means MediaPlayer (or the receipt of the chunks by hand), write in the comments.

Therefore, if in your case, you have enough call MediaPlayer.setDataSource(Uri uri) , you can skip the next paragraph for more in her and does not tell.

If you also had to get the flow manually, I will turn your attention to a couple of points, the rest just show you the code, it should tell it all himself:

An example of vimeoid: VimeoVideoPlayingTask
Called from aktiviti: Player
Leyaut: player.xml

Load flow better using AsyncTask . I just aggregate MediaPlayer inside ...PlayingTask for convenience, you can choose any other way, but it's definitely better to get flow through AsyncTask . In this case, the methodonPreExecute you can prepare your player and customize it to doInBackground get the video stream and return the stream to onPostExecute , where and start playing. Again, it is convenient to display the download progress percentage, because doInBackground known quantity of the data.

If the boot stream is thrown, the message it has shown through runOnUiThread , because the task was interrupted.

Running getWindow().setFormat(PixelFormat.TRANSPARENT); intended to displayed over player types do not go over it after hiding it. Although if you want to use ViewSwitcher , it still does not help.

The code of the stream on the URL something like this:

 public static InputStream getVideoStream (long videoId) 
        throws FailedToGetVideoStreamException, VideoLinkRequestException {
     try {           
         final HttpClient client = new DefaultHttpClient ();
         .  .  .
         HttpResponse response = client.execute (request);
         if ((response == null) | | (response.getEntity () == null))
             throw new FailedToGetVideoStreamException ("Failed to get video stream");
         lastContentLength = response.getEntity (). getContentLength ();
         return response.getEntity (). getContent ();
     } Catch (URISyntaxException use) {
         throw new VideoLinkRequestException ("URI creation failed:" + use.getLocalizedMessage ());
     } Catch (ClientProtocolException cpe) {
         throw new VideoLinkRequestException ("Client call failed:" + cpe.getLocalizedMessage ());
     } Catch (IOException ioe) {
         throw new VideoLinkRequestException ("Connection failed:" + ioe.getLocalizedMessage ());
     }
 }

9. Queues of `AsyncTask`

If you often have to perform several background tasks one by one (when completed one - to run the next), this free pattern that hides itself in the transitions to the linked list, you will do. For example, you might want to run at startup Activity consecutive multiple requests to the API of a Web service or database. The main thing is that the parameter types and result of all these problems have always been the same.

Here is the interface problem, which knows that it has the following problem:

 public interface HasNextTask <Params> {
     public int getId ();
     void setNextTask (HasNextTask <Params> task);
     public HasNextTask <Parames> getNextTask ();
     public AsyncTask <?,?,?> execute (Params. .. params); 
                          / / Overlap with AsyncTask <Params, ...>
 }

An interface that monitors all the moments when the task successfully or unsuccessfully performed:

 public interface PerformHandler <Params, Result> {
     public void onPerfomed (int taskId, Result result, HasNextTask <Params> nextTask);
     public void onError (Exception e, String description);
 }

The interface HasNextTask . What is represented by dots, can be taken in the child class or the class itself to make the abstract, that the methods doInBackground / onPostExecute implemented directly in createTask queue:

 public class TaskInQueue <Params, Result> extends AsyncTask <Params, Void, Result> 
                                          implements HasNextTask <Params> {

     private final int taskId;
     private HasNextTask <Params> nextTask = null;
     private final PerformHandler <Params, Result> listener;

     public TaskInQueue (PerformHandler <Params, Result> listener, int taskId) {
         this.taskId = taskId;
         this.listener = listener;
     }

     @ Override
     public Result doInBackground (Params. .. params) {.  .  .  / * Task * /}

     @ Override
     protected void onPostExecute (Result result) {
         .  .  .  / / Handle the result if necessary
         listener.onPerformed (taskId, result, nextTask);
     }

     @ Override public int getId () {return taskId;}

     @ Override 
     public void setNextTask (HasNextTask <Params> nextTask) {
         if (this.nextTask! = null) 
             throw new IllegalStateException ("Next task is already set");
         this.nextTask = nextTask;
     }

     @ Override
     public HasNextTask <Params> getNextTask () {return nextTask;};

 }

And most importantly, the implementation of the queue:

 public abstract class TasksQueue <Params, Result> 
                 implements PerformHandler <Params, Result>, Runnable {

     public static final String TAG = "TasksQueue";

     private HasNextTask <Params> firstTask = null;
     private HasNextTask <Params> lastTask = null;
     private Map <Integer, Params> tasksParams = null;
     private int currentTask = -1;
     private boolean running = false; / / now runs one of the tasks
     private boolean started = false; / / turn launched
     private int size = 0;

     protected HasNextTask <Params> createTask (int taskId) {/ / you can override
         return new TaskInQueue <Params, Result> (this, taskId);
     }

     @ Override
     public HasNextTask <Params> add (int taskId, Params params) {
         Log.d (TAG, "Adding task" + taskId);
         final HasNextTask <Params> = createTask (taskId);
         if (isEmpty ()) {
             firstTask = task;
             lastTask = task;
             tasksParams = new HashMap <Integer, Params> ();
         } Else {
             lastTask.setNextTask (task);
             lastTask = task;
         }
         tasksParams.put (task.getId (), params);
         size + = 1;
         return task;
     }

     @ Override
     public void run () {
         Log.d (TAG, "Running first task");
         if (! isEmpty ())
             try {
                 started = true;
                 execute (firstTask);
             } Catch (Exception e) {
                 onError (e, e.getLocalizedMessage ());
                 finish ();
             }
         else throw new IllegalStateException ("Queue is empty");
     }

     @ Override
     public void onPerfomed (int taskId, Result result, HasNextTask <Params> nextTask) {
         Log.d (TAG, "Task" + taskId + "performed");
         if (taskId! = currentTask) 
             throw new IllegalStateException ("Tasks queue desynchronized");
         running = false;
         try {
             if (nextTask! = null) {
                 execute (nextTask);
             } Else finish ();
         } Catch (Exception e) {
             onError (e, "Error while executing task" + 
                        ((NextTask! = Null)? NextTask.getId (): taskId));
             finish ();                
         }
     }

     protected void execute (HasNextTask <Result> task) throws Exception {
         Log.d (TAG, "Trying to run task" + task.getId ());
         if (running) throw new IllegalStateException ("Tasks queue desynchronized");
         currentTask = task.getId ();
         running = true;
         Log.d (TAG, "Running task" + task.getId ());
         task.execute (tasksParams.get (task.getId ())). get (); / / wait for result
     }

     protected void finish () {
         firstTask = null;
         lastTask = null;
         if (tasksParams! = null) tasksParams.clear ();
         tasksParams = null;
         currentTask = -1;
         running = false;
         started = false;
         size = 0;
     }

     public boolean isEmpty () {return (firstTask == null);}

     public boolean started () {return started;}

     public boolean running () {return running;}

     public int size () {return size;}        

 }

Now in your aktiviti at any time you can easily create all background tasks:

 protected final TasksQueue secondaryTasks;

 private final int TASK_1 = 0;
 private final int TASK_2 = 1;
 private final int TASK_3 = 2;

 public ... Activity () {/ / constructor

     secondaryTasks = new TasksQueue <..., ...>() {

         / / Here you can override createTask 

         @ Override public void onPerfomed (int taskId, ... result) throws JSONException {
             super.onPerfomed (taskId, result);
             onSecondaryTaskPerfomed (taskId, result);
         }

         @ Override public void onError (Exception e, String message) {
             Log.e (TAG, message + "/" + e.getLocalizedMessage ());
             Dialogs.makeExceptionToast (ItemsListActivity.this, message, e);
         }

     };

     secondaryTasks.add (TASK_1, ...);
     secondaryTasks.add (TASK_2, ...);
     secondaryTasks.add (TASK_3, ...);

 }

 protected void someMethod () {
     .  .  .
     if (! secondaryTasks.isEmpty ()) secondaryTasks.run ();
     .  .  .
 }

 protected void onSecondaryTaskPerfomed (int taskId, ... result) {
     switch (taskId) {
         case TASK_1:.  .  .
         case TASK_2:.  .  .
         case TASK_3:.  .  .
         .  .  .
     }
 }

By the way, thanks to the interface Runnable such a queue can be run in a separate thread:

 new Thread (secondaryTasks, "Tasks Queue"). start ();

In turn vimeoid: ApiTasksQueue
Created in: SingleItemActivity
Initialized in the task: UserActivity
Processing of completed tasks in: UserActivity

10. Backlight selection in ListView

In the picture shows a blue band, this custom highlight the selected item, it has four states - pressed, which has a focus that is prohibited by and pressed the animation of the transition from a jammed for a long tapa. The first three and squeezed state - the so-called 9-patch , you've probably heard about them , the animation - xml -file animations.

In order to describe the state to highlight the selection in the layout, specifyandroid:listSelector="@drawable/selector_bg" for your ListView .

selector_bg.xml - this is another xml -file, a set of rules about how the backlit, depending on conditions. The system goes through each rule and as soon as the first rule is matched, it is true, but these are ignored. The algorithm is simple, but the build rules in the right order do not always work out right away. See examples:

From 9-patch is a cunning, too, just what is wrong in the layout - and they drive around and goes around the entire list, too. The main rule is - check the above description of the ListView , make sure that layout_width andlayout_height installed fill_parent and also double-check the items above in the hierarchy. Then, if you did not help, you can correct the nine-patch. Thin black lines denote the top and left of the images that will be stretched if the content is not got a picture. Thin black lines (optional) on the right and bottom indicate the region in which the content itself will be written. Find the right position, too, turns out not once, have to experiment. Do not even think to create a nine-patch without an editor of the box, it is unnecessary removal of the brain - areas highlighted in the editor for content and errors, and even when everything seems right, do not always perceived layout infleyterom as expected.

11. Add QuickActions

QuickActions - a small library for pop-up dialogs with activities such as in the figure (and not only these, because their design can be changed easily.) They have become a new popular trend of the appearance of an official twitter client. Must be other implementation, in vimeoid I use this, and it also touched up a bit for their needs.

In order to display a dialog instead of the context menu when you long to Tape element on the list, enough to override a method onCreateContextMenu in ListActivity as follows:

 public void onCreateContextMenu (ContextMenu menu, View v, ContextMenuInfo menuInfo) {      
     .  .  .
     final AdapterView.AdapterContextMenuInfo info = extractMenuInfo (menuInfo);
     final QuickAction quickAction = 
           createQuickActions (info.position, getItem (info.position), info.targetView);
     if (quickAction! = null) quickAction.show ();
 }

 protected QuickAction createQuickActions (final int position, final ... item, View view) {
     QuickAction qa = new QuickAction (view);
     qa.addActionItem (getString (R.string ...), 
                      getResources (). getDrawable (R.drawable ...), 
             new QActionClickListener () {
                 @ Override public void onClick (View v, QActionItem item) {
                     .  .  .
                 }
             });
     .  .  .
     return qa;
 }

The directory containing the modified Library lib-qactions
Used in: VideosActivity

About adding an external library in the Eclipse project described in this article . In short, it is enough to create a separate library for Android-source project, set the checkbox isLibrary see Android in the properties of this project, and in the main project add to a project with a library point of Library -> Add from the same section. In this case R -file from the project with the library will be added to the main project.

12. Three more small solving

12a. A single place to call various activity

If your application aktiviti many different and they are invoked in a similar way, it might be convenient to transfer their calls including filling Extras in a separate class:

An example of vimeoid: Invoke

12b. About placeholder in localization

Maybe this is obvious, but the rows of strings.xml pleyshodery can use to substitute some value independent of the locale inside the lines, for example: <string name="image_info">Image size: {width}x{height}</string> . This function will format , so you can call: format(getString(R.string.image_info), "width", String.valueOf(600), "height", String.valueOf(800)) :

 public static String format (String source, String ... params) {
     String result = source;
     int pos = 0;
     while (pos <params.length) {
         result = result.replaceAll ("\ \ {" + params [pos + +] + "\ \}", params [pos ++]);
     }
     return result;
 }

Upd. It turned out as I thought it was a bicycle: There is a standard function getString(int resId, Object... formatArgs) . Thank zochek .

12c. About incorrect layout

Be sure to read these articles in infleyter android really very sensitive to the complex structures and if you write a complex application, leyauty sooner or later will have to optimize:

My pererenderivayuschiesya leyauty often at one point and failed getView adapter has called almost every second (and still sometimes is, but already much less). After replacing many nested slozhnostrukturirovannyhLinearLayout s to less invested and elegant RelativeLayout , infleyteru was clearly easier and myself too, because the hierarchy has become shorter and make small changes to become easier. I have not yet had time to replace everywhere, but now otnoschus to leyautam carefully. Also watch out for, so thatwidth/height=wrap_content used only possible for simple elements, the use of wrap_content as parameters the width / height LinearLayout and other complex types can lead to difficult consequences.

Android Calendar API

2011-09-29T11:00:00.000-07:00

This article focuses on the use of undocumented API to work with standard calendar Android.
For what?!
I ran into this problem when he wrote an application to form an university schedule. It is convenient to have their schedules separately, so even a standard calendar does not support repeating events in one week, which is necessary for a two-week (Thu / odd.) Schedule. Idée fixe was a function of the application, which will "fill" introduced by the schedule Android calendar. Pluses are obvious: Sync with Google Calendar from google (pardon the tautology), built-in calendar widget (very much good this widget from HTC Sense) and a mountain of widgets from third-party manufacturers, which show at least the next event, though utilization of the week, etc.

Use an undocumented API - this is BAD! Got it?

Does that solve the problem of the obvious need to use an undocumented API? The answer - no. The proper method is to use the API Google Calendar, I advise you andmake my own applications.

But the "right" method imposes several limitations:
• Do not use the lack of connection to the Internet;
• the need to synchronize the calendar after filling;
• Data (and there are not enough in filling the whole year) go to the server and then goback in sync, which obviously increases the traffic in half.

In my opinion, is much more convenient to use the offline version of the calendar, whichat any opportunity, you can synchronize with guglokalendarem. Unfortunately google did not care about developers for Android and has not published an official API, but to our delight Android source code open and intelligent people have long found the magic URIcontent providers.

We ask the user for permission to work with calendar

Paradox. API does not have, and resolution of the documentation is. You just have toadd them to vashAndroidManifest.xml.

<uses-permission android:name="android.permission.READ_CALENDAR"> </uses-permission>
<uses-permission android:name="android.permission.WRITE_CALENDAR"> </uses-permission>

URI

To use the calendar, Android, we must turn to its content provider for a particular URI.Much to our chagrin that the URI is different in different versions of operating systems andis likely to change in the next (the costs of undocumented API). But the problem is solved.
For Froyo [2.2] and is likely for the following versions-content: / / com.android.calendar / calendars.
For versions <2.2 - content: / / calendar / calendars.
As you can see, it's not so bad. You can determine the version of the system and use the appropriate URI, but I went the other way. I watch if there's a URI for <2.2 and if there is no one, then use the remainder.

// Calendar URI before 2.2
Uri calendars = Uri.parse("content://calendar/calendars");
Cursor managedCursor = this.managedQuery(calendars, new String[] { "_id", "name" }, null, null, null);
if(managedCursor == null || managedCursor.getCount() == 0)
{
 // 2.2 (Froyo)
}
else
{
 // < 2.2
}

We assume that the URI received.

Get the list of calendars

For users of Google Calendar do not have to explain, and explain to the rest. Public Access consists of one or several small calendars, which can vary in color markers. This is usually something like "personal", "work", "training", etc. Establish such calendars canonly visit guglokalendarya, in the android that standard means you can do.
To add an event, we need to know the ID of the calendar. To perform this task, use the construction of the preceding paragraph.

String[] projection = new String[] { "_id", "name" };
Cursor managedCursor = this.managedQuery(URI, projection, null, null, null);
if (managedCursor != null && managedCursor.moveToFirst()) 
        {
         String calName;
         String calID;         
         int nameColumn = managedCursor.getColumnIndex("name");
         int idColumn = managedCursor.getColumnIndex("_id");
         do 
         {
          calName = managedCursor.getString(nameColumn);
          calID = managedCursor.getString(idColumn);
          if (calName != null) // … UI         
            } while (managedCursor.moveToNext());
            managedCursor.close();
        }

Now the resulting set of names can be displayed in the interface and allow the user to choose.

Add event

Then work with the calendar is, as with any other content provider. This can be read in the documentation.

ContentValues event = new ContentValues();
event.put("calendar_id", calID);  // ID календаря мы получили ранее
event.put("title", title); // Название события
event.put("description", desc); // Описание события
event.put("eventLocation", loc); // Место проведения
event.put("dtstart", start); // время начала
event.put("dtend", end); // время окончания
eventsURI=Uri.parse(URI + “/events"); 
this.getContentResolver().insert(eventsURI, event);

Let's talk about the fields of the event. The description field, I advise you to use to indicateevents. Use this field can then be removed en masse all the events generated by your program. Field names, descriptions and venue are string. We should also mention thetime field. These fields have type long, but these fields can be generated, for example,the following function.

public static long pickDate(int year, int month, int day, int hour, int minute) 
{
     Calendar rightNow = Calendar.getInstance();
     int timeShift = rightNow.get(Calendar.ZONE_OFFSET);     
     return Date.UTC(year - 1900, month, day, hour - (timeShift / 3600000), minute, 0);
}

With her, I think, will understand themselves, let me note only that it responds to thecurrent time zone.

Remove Event
To delete a message by ID to add it to the URI.

//eventsURI = URI + events/
uri = ContentUris.withAppendedId(eventsURI, EVENT_ID);
this.getContentResolver().delete(uri, null, null);

To remove the other fields you can get all mouse events, like we did with the calendars, and then selectively remove the ID.

Finally

In conclusion, I remind you that you're using it at your own risk. During development, Ionce wrote a URI is not and my phone every time you sync started to issue an error (corrected erasure of information from the calendar altogether.)
Another trouble - the emulator is no calendar, for it to repeat all the above fails.
And it concluded. I can not take the opportunity popiarit the application, which was discussed in the article. You can find it in the market under the name uTimetable.

A bug in Android or problem with Spinner in full screen mode

2011-09-29T10:33:00.000-07:00

Yesterday, my friend Max wrote me in GTalk about one unusual problem. He develops a kind of full-screen application that calls a dialogue with the widget Spinner. And it would be cool, but there is a bug - when you click on the Spinner in full screen mode with the appearance of selection dialog Status Bar appears for 1-2 seconds. This situation occurs if the Spinner is a large number of items. It looks like this:

I began to explore the sources of the Spinner and discovered that when displaying the dialog with the elements when you click on - Spinner creates a dialogue that does not include the full screen version. The code looks as follows.

    @Override
    public boolean performClick() {
        boolean handled = super.performClick();
        if (!handled) {
            handled = true;
            Context context = getContext();
            final DropDownAdapter adapter = new DropDownAdapter(getAdapter());
            AlertDialog.Builder builder = new AlertDialog.Builder(context);
            if (mPrompt != null) {
                builder.setTitle(mPrompt);
            }
            mPopup = builder.setSingleChoiceItems(adapter,
                    getSelectedItemPosition(), this).show();
        }
        return handled;
    }

There was only one solution in my head - create a class based on the Spinner and cut off his metod performClick (). But the difficulty lies in the fact that the reference to dialogue Spinner is stored in the private variable mPopup. This problem, we went around, using reflection to access this variable after you create the dialog and call the method necessary to set the properties dialog to properly display it full screen. To increase the security of this method for the solution to our problem, we abstracted from the field name and mPopup just the cycle of looking for a variable of type AlertDialog, so even if the developers change the name of the variable, the code will work. Here is the code of the new class:

package maximyudin.spinnerbug;
import java.lang.reflect.Field;import android.app.AlertDialog;
import android.content.Context;
import android.util.AttributeSet;
import android.view.WindowManager;
import android.widget.Spinner;

public class NoTitleSpinner extends Spinner {
    public NoTitleSpinner(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public NoTitleSpinner(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public NoTitleSpinner(Context context) {
        super(context);
    }

    @Override
    public boolean performClick() {
        boolean status = super.performClick();
        Field privateStringField = null;
        try {
            Field[] fields = Spinner.class.getDeclaredFields();
            for (Field field : fields) {
                if (field.getType().getName()
                        .equals(AlertDialog.class.getName())) {
                    privateStringField = field;
                    break;
                }
            }
            if (privateStringField == null) {
                return false;
            }

            privateStringField.setAccessible(true);
            AlertDialog dialog = (AlertDialog) privateStringField.get(this);
            dialog.getWindow().setFlags(
                    WindowManager.LayoutParams.FLAG_FULLSCREEN,
                    WindowManager.LayoutParams.FLAG_FULLSCREEN);
        } catch (IllegalArgumentException e) {
        } catch (IllegalAccessException e) {
        }
        return status;
    }
}

Now instead of Spinner you need to use our NoTitleSpinner in the code and xml.

Fully project code posted here.

P.S. We've added this bug to the bug-report - follow the news here — code.google.com/p/android/issues/detail?id=11419

Android dialog box with icons in the menu

2011-09-29T10:11:00.000-07:00

The idea was conceived Insanely simple and I would even say stupid. And when I startedto do something here that I wanted to do dramatically beautiful dialog box by selecting themenu icons. Such a dialogue is present in the standard Android, for example, a long tapon the desktop opens the dialog to add content (widget oboiny, etc.). So, welcome to acat ...

As mentioned above, in front of me was to make a dialog box like this:

Googling for a while and reading the official docks on the platform I could not find how to implement such a dialogue. After some time of digging, I found a result that will most quickly apparent to experienced Android developers.
The answer was simple and he was lying on the surface. Its essence is that for the dialogyou just need to substitute the Builder the appropriate data provider (of course, the provider must write themselves.)
So now there will be some amount of code with comments about what's going on.

The list of (ISP) the possible types of accounts

public final class AccountTypesProvider {
public static List<AccountType> accountTypes = Collections.unmodifiableList(Arrays.asList( new AccountType(AccountType.TWITTER_ACCOUNT, "Twitter", R.drawable.twitter_icon_big), new AccountType(AccountType.FACEBOOK_ACCOUNT, "Facebook", R.drawable.facebook_icon_big), new AccountType(AccountType.BUZZ_ACCOUNT, "Google Buzz", R.drawable.buzz_icon_big), new AccountType(AccountType.LINKEDIN_ACCOUNT, "LinkedIn", R.drawable.linkedin_icon_big), new AccountType(AccountType.VKONTAKTE_ACOUNT, "ВКонтакте", R.drawable.vkontakte_icon_big) )); }
* This source code was highlighted with Source Code Highlighter.

This is a simple wrapper around a list of possible types of accounts. Account Type is a simple POJO class that consists of an identifier (a constant), the name of the service andthe resource identifier icons for this type of service.

ListAdapter to display a list of account types in a given layout'e

public final class AccountsTypesListAdapter extends ArrayAdapter<AccountType> {
private Activity context; private List<AccountType> accountTypes; public AccountsTypesListAdapter(Activity context, List<AccountType> accountTypes) { super(context, R.layout.select_account_item, accountTypes); this.context = context; this.accountTypes = accountTypes; } @Override public View getView(int position, View convertView, ViewGroup parent) { LayoutInflater inflater = context.getLayoutInflater(); View row = inflater.inflate(R.layout.select_account_item, parent, false); TextView label = (TextView) row.findViewById(R.id.text_item); label.setText(accountTypes.get(position).title); ImageView icon = (ImageView) row.findViewById(R.id.icon_item); icon.setImageResource(accountTypes.get(position).bigIconId); return row; } }
* This source code was highlighted with Source Code Highlighter.

First you need to pass the constructor a list of types that will work with the adapter list.Binding to specific item'a leyautu occurs in the overridden method getView (). It is loadedleyaut of the specified resource is retrieved widgets and they recorded data on a particular element of the list. Incidentally, the index of that element is automatically available through the option position.

This list adapter works with just such a layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="10px"> <ImageView android:id="@+id/icon_item" android:layout_width="wrap_content" android:layout_height="fill_parent"/> <TextView android:id="@+id/text_item" android:layout_width="wrap_content" android:layout_height="fill_parent" android:paddingLeft="10px" android:paddingTop="5px" android:textStyle="bold" android:textColor="#000000"/> </LinearLayout>
* This source code was highlighted with Source Code Highlighter.

All that now remains - is designed to tie a sheet-adapter-specific dialog

public static void showSelectAccountTypeDialog(Activity context, String title, OnClickListener dialogListener) {
AlertDialog.Builder builder = new AlertDialog.Builder(context); builder.setTitle(title); builder.setAdapter(new AccountsTypesListAdapter(context, AccountTypesProvider.accountTypes), dialogListener); builder.create().show(); }
* This source code was highlighted with Source Code Highlighter.

and call activity dialogue in the right place

private void displaySelectAccountTypeDialog() {
ApplicationDialogs.showSelectAccountTypeDialog(this, "Select network", new OnClickListener() { @Override public void onClick(DialogInterface dialogInterface, int selectedItemId) { setupAccount(selectedItemId); } }); }
* This source code was highlighted with Source Code Highlighter.

Dialogue after its completion will return the index of the parameter item'a selectedItemIdin the listener, which is specified when calling the dialogue. In this simple case, this indexcoincides with the ID type of account (item'a in the list), so no additional changes orextractions are required. For my problem the index is more than enough.
In the end, I turned a nice dialogue

NumberPicker use and customization of its appearance

2011-09-28T15:54:00.000-07:00

Probably many of you have used widgets such as DatePicker and TimePicker. But the functionality of the widget is limited ability to choose the date and time, but I wanted more- to use this feature to select any number in a specified range (as inkontroleNumericUpDown in C #). Such a possibility exists. DatePicker widget andsystem-based TimePicker widget NumberPicker, you can not use the box. To use it you need to write a little code.

First, add NumberPicker in our main layout, xml-code is as follows:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" android:layout_height="fill_parent">
    <com.android.internal.widget.NumberPicker
        android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:id="@+id/numTestNumberPicker" android:layout_centerInParent="true">
    </com.android.internal.widget.NumberPicker>
</RelativeLayout>

We have 3 NumberPicker method that we need setRange, getCurrent and setCurrent. I guess by the names of the methods, it is clear that they do. The difficulty is that these methods are hidden for the developer and they can only call using reflection. For ease of use, I wrote a helper-class that allows you to work with these methods. Class code is shown below:

package maximyudin.NumberPickerDemo;

import java.lang.reflect.Method;

public class NumberPicker {
    private Object picker;
    private Class<?> classPicker;

    public NumberPicker(Object o) {
        picker = o;
        classPicker = picker.getClass();
    }

    public void setRange(int start, int end) {
        try {
            Method m = classPicker.getMethod("setRange", int.class, int.class);
            m.invoke(picker, start, end);
        } catch (Exception e) {
        }
    }

    public Integer getCurrent() {
        Integer current = -1;
        try {
            Method m = classPicker.getMethod("getCurrent");
            current = (Integer) m.invoke(picker);
        } catch (Exception e) {
        }
        return current;
    }

    public void setCurrent(int current) {
        try {
            Method m = classPicker.getMethod("setCurrent", int.class);
            m.invoke(picker, current);
        } catch (Exception e) {
        }
    }
}

In konstrukture class passed a real object NumberPicker (which LinearLayout), obtained by findViewById of our main layout. Consider how to use freshly NumberPicker in practice.

package maximyudin.NumberPickerDemo;

import android.app.Activity;
import android.os.Bundle;
import android.widget.LinearLayout;

public class NumberPickerDemo extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        LinearLayout numTestNumberPickerView = (LinearLayout) findViewById(R.id.numTestNumberPicker);
        NumberPicker numTestNumberPickerObject = new NumberPicker(
                numTestNumberPickerView);

        numTestNumberPickerObject.setRange(1, 100);
        numTestNumberPickerObject.setCurrent(50);
        int currentPos = numTestNumberPickerObject.getCurrent();
    }
}

Basically all quite simple when using the helper-class. The screen looks as follows:

We now proceed to the second part of the article - full change in the appearance of the widget. For this purpose, a set of prepared me pictures (from my program MyTasks) different states of the buttons ('+' and '-') and a text field widget, it is from them is NumberPicker. Get them mozhnootsyuda.. The images presented in a format Nine-Patch (9-Patch), a type of image can be stretched, depending, for example, of their content, they are often used to set the background of various widgets, including in my case. More information on the 9-Patch you can read here. Images need to put it in the drawable, or a folder drawable-mdpi (-ldpi,-hdpi), as in my case.
In order to fit these images have earned us a way (that is responsive to the different states of widgets) necessary to form three xml-file-selector in the format (a file on each widget - two buttons and a text box). The selector is a set of elements with attributes, which represent different states of the widget (selected, pressed, inactive, etc.). These files can also be placed under the drawable, or drawable-mdpi (-ldpi,-hdpi). Below are the three files.
Button for '+' (timepicker_up_btn.xml)

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="schemas.android.com/apk/res/android">
    <item android:state_pressed="false" android:state_enabled="true"
        android:state_focused="false" android:drawable="@drawable/btn_up_picker_notselected" />
    <item android:state_pressed="true" android:state_enabled="true"
        android:drawable="@drawable/btn_up_picker_pressed" />
    <item android:state_pressed="false" android:state_enabled="true"
        android:state_focused="true" android:drawable="@drawable/btn_up_picker_selected" />
    <item android:state_pressed="false" android:state_enabled="false"
        android:state_focused="false" android:drawable="@drawable/btn_up_picker_disabled" />
    <item android:state_pressed="false" android:state_enabled="false"
        android:state_focused="true" android:drawable="@drawable/btn_up_picker_disabled_focus" />
</selector>

For a text box (ed_picker_background.xml)

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="schemas.android.com/apk/res/android">
    <item android:state_window_focused="false" android:state_enabled="true"
        android:drawable="@drawable/edit_picker_notselected" />
    <item android:state_window_focused="false" android:state_enabled="false"
        android:drawable="@drawable/edit_picker_notselected" />
    <item android:state_pressed="true" android:drawable="@drawable/edit_picker_pressed" />
    <item android:state_focused="true" android:state_enabled="true"
        android:drawable="@drawable/edit_picker_selected" />
    <item android:state_enabled="true" android:drawable="@drawable/edit_picker_notselected" />
    <item android:state_focused="true" android:drawable="@drawable/edit_picker_notselected" />
    <item android:drawable="@drawable/edit_picker_notselected" />
</selector>

For button '-' (timepicker_down_btn.xml)

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="schemas.android.com/apk/res/android">
    <item android:state_pressed="false" android:state_enabled="true"
        android:state_focused="false" android:drawable="@drawable/btn_down_picker_notselected" />
    <item android:state_pressed="true" android:state_enabled="true"
        android:drawable="@drawable/btn_down_picker_pressed" />
    <item android:state_pressed="false" android:state_enabled="true"
        android:state_focused="true" android:drawable="@drawable/btn_down_picker_selected" />
    <item android:state_pressed="false" android:state_enabled="false"
        android:state_focused="false" android:drawable="@drawable/btn_down_picker_disabled" />
    <item android:state_pressed="false" android:state_enabled="false"
        android:state_focused="true" android:drawable="@drawable/btn_down_picker_disabled_focus" />
</selector>

Now we need to slightly modify the constructor helper-class that was created forNumberPicker at the outset. This will allow us to create an object NumberPicker change the appearance of its components. The code of the modified class is shown below.

package maximyudin.NumberPickerDemo;

import java.lang.reflect.Method;

import android.view.View;
import android.widget.EditText;
import android.widget.LinearLayout;

public class NumberPicker {
    private Object picker;
    private Class<?> classPicker;

    public NumberPicker(LinearLayout numberPickerView) {
        picker = numberPickerView;
        classPicker = picker.getClass();

        // Кнопка '+', тип - NumberPickerButton
        View upButton = numberPickerView.getChildAt(0);
        upButton.setBackgroundResource(R.drawable.timepicker_up_btn);

        // Текстовое поле, тип - EditText
        EditText edDate = (EditText) numberPickerView.getChildAt(1);
        edDate.setTextSize(17);
        edDate.setBackgroundResource(R.drawable.ed_picker_background);

        // Кнопка '-', тип - NumberPickerButton
        View downButton = numberPickerView.getChildAt(2);
        downButton.setBackgroundResource(R.drawable.timepicker_down_btn);
    }

    public void setRange(int start, int end) {
        try {
            Method m = classPicker.getMethod("setRange", int.class, int.class);
            m.invoke(picker, start, end);
        } catch (Exception e) {
        }
    }

    public Integer getCurrent() {
        Integer current = -1;
        try {
            Method m = classPicker.getMethod("getCurrent");
            current = (Integer) m.invoke(picker);
        } catch (Exception e) {
        }
        return current;
    }

    public void setCurrent(int current) {
        try {
            Method m = classPicker.getMethod("setCurrent", int.class);
            m.invoke(picker, current);
        } catch (Exception e) {
        }
    }
}

The result is shown in the figure below.

Full project source

In this article of mine is complete, I hope I helped you learn something new. Waiting forcomments and amendments, if there is someone to that offer.

How to make android user interfase (UI) more easy

2011-09-28T12:31:00.001-07:00

I thought that it would be nice to have a program / site to automatically generate UI and simply drag and drop items. I found this.

Have a nice day!

User notification: Toast

2011-09-28T11:27:00.000-07:00

Hi!
I'm begining a series of articles about how to alert the user. Course is designed for beginners.There are three ways to alert the user: Toast, Notification and through different types of Dialog. Today I will discuss of the first type of warning - Toast.
Introduction
Toast is a pop-up window that allows you to quickly notify the user about the event has occurred, such as maintaining the program settings to SD-card. Toast feature is that during the message, the user can interact with them is behind Activity, or with a home screen (home screen). Also worth noting that the user can not control the closing of Toast with hardware Back button or other possible means, the message appears and then smoothly itself as smoothly disappears. The time delay between the appearance and disappearance can be set programmatically. In most cases, Toast is a short message, but there is an opportunity to ask any appearance of Toast, for example, add an image next to the text. In addition, you can control the location of Toast on the screen.Toast can be created from an Activity, or from the Service. In the case of a service Toast appears on top of Activity, which has the focus, or top of the home screen.

Create a simple Toast
Create a simple Toast can be a static method of class makeText Toast, setting the necessary parameters.

Toast.makeText(getApplicationContext(), "Привет, мир!", Toast.LENGTH_SHORT).show();

The details given application context, the message delay and wrote about earlier. The message can be set directly in the form of text, or using a text-line resource, for example, R.string.hello_world, which stores the text to be displayed, in this case, "Hello,world!". The delay may be short - LENGTH_SHORT, or long - LENGTH_LONG. By default, the Toast is given a short delay. The software delay is given by setDuration.

The essence of the method makeText is: inside the method creates an Toast, set the text and type of delay. Further, the object can be either used, as in my case, the methodshow, which displays created by Toast, or set additional properties Toast, for example, its location on the screen, or you create the look.

Toast created as follows:

Change the position of Toast

Toast on the screen location specified by the method setGravity as follows:

Toast toast = Toast.makeText(getApplicationContext(), "Привет, мир!",
Toast.LENGTH_LONG);toast.setGravity(Gravity.CENTER, 0, 0);
toast.show();

The first parameter sets the alignment method, versions of which quite a lot in the class of Gravity. The second and third parameters specify how many pixels will be shifted horizontally to the right Toast and vertically downward, respectively, relative to the value in the first parameter. The result of the above code displays as follows:

Adding images in an easy Toast
To add an image in standard Toast software required to create an object of class ImageView and ask for a picture of the resources using the setImageResource. You will then get the standard look of Toast, if you look in the debugger it is LinearLayout, and add the created object ImageView showing in what position to add a picture, in my case I have a zero position so that the image has been added above the text. Code to create this image with Toast is presented below.

Toast toast = Toast.makeText(getApplicationContext(), "Привет, мир!", Toast.LENGTH_LONG);
toast.setGravity(Gravity.CENTER, 0, 0);
LinearLayout toastView = (LinearLayout) toast.getView();
ImageView imageWorld = new ImageView(getApplicationContext());
imageWorld.setImageResource(R.drawable.world);
toastView.addView(imageWorld, 0);
toast.show();

Toast thus created is as follows:

Toast the creation of complex

To create a complex Toast to create your own layout, code is as follows:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="schemas.android.com/apk/res/android"
android:layout_height="wrap_content" android:layout_width="wrap_content"
android:background="#ffffffff" android:orientation="vertical"
android:id="@+id/llToast">
<TextView android:layout_height="wrap_content"
  android:layout_margin="1dip" android:textColor="#ffffffff"
  android:layout_width="fill_parent" android:gravity="center"
  android:background="#bb000000" android:id="@+id/tvTitleToast"></TextView>
<LinearLayout android:layout_height="wrap_content"
  android:orientation="vertical" android:id="@+id/llToastContent"
  android:layout_marginLeft="1dip" android:layout_marginRight="1dip"
  android:layout_marginBottom="1dip" android:layout_width="wrap_content"
  android:padding="15dip" android:background="#44000000">
<ImageView android:layout_height="wrap_content"
   android:layout_gravity="center" android:layout_width="wrap_content"
   android:id="@+id/tvImageToast" />
<TextView android:layout_height="wrap_content"
   android:paddingRight="10dip" android:paddingLeft="10dip"
   android:layout_width="wrap_content" android:gravity="center"
   android:textColor="#ff000000" android:id="@+id/tvTextToast" />
</LinearLayout>
</LinearLayout>

I created a Toast in a dialogue with the headline, which is located inside the image and text.
Now, this layout is necessary to register for Toast and ask for the message title and text, and set the image. This is done as follows:

LayoutInflater inflater = getLayoutInflater();
View layout = inflater.inflate(R.layout.toast,
(ViewGroup) findViewById(R.id.llToast));
ImageView image = (ImageView) layout.findViewById(R.id.tvImageToast);
image.setImageResource(R.drawable.world);
TextView title = (TextView) layout.findViewById(R.id.tvTitleToast);
title.setText("Внимание");
TextView text = (TextView) layout.findViewById(R.id.tvTextToast);
text.setText("Привет, мир!");

Toast toast = new Toast(getApplicationContext());
toast.setGravity(Gravity.RIGHT | Gravity.TOP, 12, 40);
toast.setDuration(Toast.LENGTH_LONG);
toast.setView(layout);
toast.show();

The first two lines are initialized by filling the View object to xml-file from (used for thisinstance LayoutInflater, obtained by the method getLayoutInflater), created earlier. The first parameter of inflate sets the ID of a previously created layout - R.layout.toast (in this case, it corresponds to the file res / layout / toast.xml). Then obtained by reference to theimage, caption and text messages, and filled with the desired data. Then immediatelycreate a Toast, set the parameters and layout as the one prescribed layout, which weinitialized earlier this is done using the setView. The result of all these manipulations weget Toast, which looks like the figure below.

In this first article on how to alert the user is finished. If you find a mistake or want to addsome other ways to work with Toast, write comments, and I will add your comments in the article.

Google+ Now Open To All, With a Ton of New Features

2011-09-28T10:26:00.000-07:00

I woke up some days ago to a perfect storm of Google+ announcements. Firstly, the big news – Google+ is now available to anyone with a Google account. No invite required. This is great news, as it lowers the barrier to entry significantly. I can now invite all my friends to join, and they can invite their friends, etc. Unfortunately it also means my Google+ Invites app is now entirely obsolete. Well, that was fun while it lasted

But that’s not the only Google+ news. In the same blog post Google announced a bunch of new Hangout features, including mobile video & publicly broadcast streams. Also, you’ll now be able to share your screen and/or Google Docs with Hangout participants (which puts Google+ squarely in the business arena). And we finally have the ability to search Google+! This has probably been the most requested feature, and the ability to search posts as well as people makes the service far more useful.

And just in case you weren’t impressed with those features – Google published another blog post a few minutes later announcing features 101 through 107. This includes a slew of mobile features, such as +mentions, the ability to +1 comments, and change your profile picture all from the mobile app. These are more incremental updates, but it’s great to see Google actively pushing development like this, and responding to the small features that people have been asking for. I don’t know any other Google product which has had so many feature updates in such a short period of time. Hopefully they continue to keep up the good work. I believe Google+ has huge potential, and it’s by far the most promising social service from Google yet.

Something interesting to note (in case you thought this post wasn’t related to Android development ), Google seems to be having difficulty synchronizing feature releases between their Android and iOS apps. This stands to reason – Apple requires approval for updates in the App Store, while Google would have no delays releasing an app on the Android Market. But this is a significant area of concern for many developers. The more app stores you distribute to, the harder it becomes to keep them all up to date. The code base will differ between stores; content policy differs; and even product packaging has to be done differently. It’s worth taking note – Google doesn’t have it any easier.

Add me if you wish =)

https://plus.google.com/100694486792208770526/posts

How to make $250 a day (and get banned from the Android Market)

2011-09-28T10:03:00.000-07:00

A few months ago I did something which, in retrospect, was probably rather stupid. But it was surprisingly successful while it lasted. As I wrote earlier, I’ve been using Google+ since the day after it was launched. I myself received an invite from a stranger who was offering invites publicly. For this reason, I’ve been keen to share invites with anyone else who’s looking for one. I put up a post on this blog offering free invites, and got a huge response from the Android community. In fact, there were so many responses that it overwhelmed my email after a few days. There’s no way I could have kept up with the demand.

Rather than stop accepting requests altogether, I wanted to make it easier to handle the load.(NB: At this stage there was no limit to the number of Google+ invites you could send.) My first thought, trying to work out a faster way to do things, was “hey, is there an Android app for this?” A quick search turned up a negative. No Android apps offering Google+ invites. So, why not make one? It seemed a pretty good idea, so I spent that afternoon writing a simple app that accepted an email address, and a description of the request. The data was sent to a PHP script on my server, so I could go through and invite the email addresses stored in a database.

Actually, it’s not that simple to write an Android app that POSTs data asynchronously to a server, checks the response, and handles errors gracefully. I re-used some classes from another unreleased project, but it was still a bigger job than I expected. But the actual coding is an issue for another day. The most interesting part came when I released the app on the Android Market.

First release

I titled my app “Google+ Invites” – since that describes it pretty well. Because I was in a bit of a hurry, I decided to just modify the official Google+ logo, so that people could easily identify it as related to the social network. This is the logo that I came up with:

A little too similar to the original perhaps? Well, I thought it was a creative adaptation and went with it. Looking in retrospect, it wasn’t the wisest idea. But that’s how the app was initially released to the Android Market, on the 9th July. By the 10th July, the Developer Console was showing 326 installs. I thought that was pretty good – about the same amount as when I first released my program. That number of installs, you can attribute to being in the “Just In” category. But this time, the downloads kept coming in. The next day there were another 300 installs. The day after, 500, then 700. By the 13th, this app had about 1,730 total installs.

By this time, there were so many people asking for invites that I simply wasn’t able to complete them all. Even with a plain-text list of email addresses, inviting someone to Google+ was (at that stage) a very manual process. I had to copy & paste every email address, click “Invite”, and then add them to one of my circles so they could see my welcome post. So I was hit with the same dilemma I had offering invites on the blog – how to cut down the number of requests, or prioritise them somehow.

The “Points” System

In the back of my mind, I knew there was some kind of advertising network that used incentive advertising. For those not familiar with the terminology – in “normal” advertising streams, the advertiser pays the publisher (app developer) when a user clicks the ad. For obvious reasons, you’re not allowed to encourage people to click these ads. But with incentive advertising, you are. Because you don’t get paid when they click an ad – you get paid when they complete an action (such as signing up, downloading an app, etc.). Looking around a little bit, I foundTapJoy, which is a fairly well established incentive advertising network. The SDK is pretty easy to setup. You actually download the source files, and include them in your app TapJoy currently doesn’t offer a JAR library option, although I’d like to see this happen some time soon. Other networks such as AdMob use the JAR method, and it’s a lot simpler to integrate with source control.

Clicking "Get Points" loads the TapJoy offerwall

Using TapJoy, I implemented a “points” system in my app. When someone downloads the app, they can submit their email address to request an invite immediately. But at this stage, they’ll be placed at the bottom of the queue. With about 2,000 invites to be processed, it could take a while to get one. If someone wants to get higher in the queue, they have to get more points. You can earn points by completing offers on TapJoy. This basically involves downloading a game, or “liking” something on Facebook. Simple tasks, mostly free, but the TapJoy pays me a small amount every time someone completes an offer. Using this method, I can hand out the first invites to people who are willing to put a bit of effort into to get one.

I’ve noticed that this system is a bit controversial. Some people see the money-making side of things, and say it’s all a scam to make profit. Well, sure – I’d love to make some profit from this app! It actually takes a lot of time to invite all those people. I don’t see anything wrong with offering people the option of paying (with their time) for priority access. I’ll still try to invite everyone, whether they’ve completed offers or not. Just the people with more points, will get processed first.

Basically I could choose between taking down the app from the Android Market due to high demand, or implementing this points system. So I opted to use TapJoy, as an experiment using incentive advertising. I actually included AdMob advertising in the same app, as a comparison. Didn’t really know what to expect, but it was a great chance to try a new system.

The Rise….

One day later, I got some pretty amazing results. Another 1000 downloads on the Android Market, 717 views of the TapJoy offerwall, and a total of $20 from TapJoy alone. In 24 hours, I made more from TapJoy than an entire month with AdMob. The eCPM for TapJoy was $28, while AdMob was about $0.10.

But I thought, maybe it won’t last. Maybe that was just a spike, and we’ll see some slightly more sane figures come out tomorrow. The next day there were over 2,000 page views, and total revenue of $56. Doesn’t look like it was a spike after all. The eCPM was very similar. So, given the huge success of the TapJoy experiment so far, I kept inviting people on Google+, so that I could justify keeping the app on the Market. I thought $50 a day was amazing, certainly considering the amount of effort it took to write the app. I’d be more than happy if it kept up the pace, and didn’t grow any further at all. But there was even more of a surprise in store. Take a look at the graph below (left hand column), showing the download figures for the “Google+ Invites” app:

Columns (left-to-right): Date, Total Downloads, Active Installs, Increase day-over-day, Percentage Active (Screenshot taken with Andlytics app)

And then look at the TapJoy revenue for the same period (up until July 17th): As the downloads shot up, so did the revenue. On the 17th of July, with 7,600 downloads I actually made $300 in a single day, just from TapJoy ads in this app! At that stage about 3,700 people had requested an invite.

….and The Fall.

But sadly, the 17th was my last day of triple-digit income. Not because of any changes by TapJoy, and certainly not due to lack of interest by users (in fact, I had just reached 2nd place on the AppBrain ”Hot Apps” list). But just before mid-day on the 17th, Google suspended my app from the Android Market. And that’s it, really.

Once the app was suspended, all the charts dropped off completely. I had the app listed on a few third-party app stores (including SlideME and Amazon), but the number of actual downloads was miniscule. The Android Market was the only one that mattered.

It was a bit scary actually – receiving an email from Google that one of my apps has been suspended. I’d always been prepared in the back of my mind, thinking that if Google has a problem with it and wants to take it down, that’s fine. I wasn’t aiming to do anything sly, and did read the terms & conditions of the Android Market and Google+ to make sure that offering invites like this wasn’t illegal in some way.

But the actual email had absolutely no information about why the app was suspended. Not a word. Here’s the full text:

Subject: Notification from Android Market
This is a notification that the application, Google+ Invites with package ID com.bb.plusinvites has been removed from Android Market due to a violation of the Developer Content Policy. Please review the Content Policies and Business and Program Policies before you create or upload additional applications. Note that repeated violations may result in a suspension of your Android Market Publisher account.
For more information, or to contact us, please reply to this email, or visit the Android Market Help Center.
Thanks,
The Android Market Team

After re-reading the policies mentioned in the email, I concluded that the most likely cause for suspension was trademark concerns. I had been very careful in the Market description (and in the app itself) to include disclaimers, mentioning that my app was in no way affiliated with Google, etc. But the logo was a major slip-up. It’s quite possible that somebody could mistake my app for an official Google app at first glance, simply due to the logo. I should have been more careful with that, but at the time I didn’t lend it a thought. I think Google would be perfectly justified in complaining, if that was indeed the problem.

What I’m not so happy about though, is Google’s communication once an app is suspended. There are absolutely no details provided about the cause. In my case, I had identified an area which was probably the cause of concern. But how do I know they won’t find some other issue to complain about? The email mentions “repeated violations may result in a suspension of your Android market Publisher account.” Should I risk losing my entire account, by changing the icon, and fixing what I could only guess was the problem?

The actual liason (if you could call it that) with the Android Market team is a topic for another time. But to cut a long story short, I eventually got a hint that trademark infringement was indeed the concern, and that I could try uploading a new version that fixed this issue. But due to some “internal accounting issues”, Google claimed they could not re-instate my app. I had to upload a new version, with a different package ID. Basically I lost my entire user base for that app, and risked losing my Android Market publisher account if I hadn’t correctly guessed the cause of infringement. A pretty big gamble if you ask me.

The new logo, sans any Google references

I did take the gamble though – and uploaded a new version called “Social Invites Plus” with a completely new logo. It seemed to pass the test, and has remained active to this date. But it hasn’t taken off like the first app did – and I’ve lost all the ratings, comments and active installs from the previous version. I can’t even release an update telling people it’s been removed.

Conclusion

I’m not too concerned about the evanescence of the current app. It was always intended to be a kind of experiment – it just happened to be a very successful experiment. Recently Google set a limit to the number of Google+ invites you can send per account. I’ve now got 150 invites remaining, so obviously I won’t be able to continue inviting everyone (although I did get through a few thousand in the preceding weeks). This means, for all intents and purposes, the Google+ Invites app (“Social Invites Plus”) is now dead.

I made note on the Android Market right from the beginning that this was an unofficial app, and therefore holds no guarantees of continuity. I’ll try to invite everyone who’s earned points so far, in consideration of the effort they put in. But for everyone else I’ve posted a message explaining the situation, and will be releasing an update on the Android Market with more details. Not much else I can do until Google opens the doors to more users. Which will happen sooner or later – but who knows when.

Despite the abrupt ending, this was a very interesting and worthwhile experience – the first app that I could really call successful, and my first experience with incentive advertising networks. What are some of the lessons I’ve learned?

Incentive advertising can be very effective
If you’ve got some goods or services of value that you can offer from within your app, incentive advertising (from companies like TapJoy) can be far more effective than click-based alternatives such as AdMob.

The Android Market is key to success
For many apps, the third-party app stores have a significant impact on sales and revenue. But for all my apps so far, the Google Android Market has been the predominating revenue generator. Without the Android Market this app would never have taken off.

Positive comments (and ratings) are worth a lot
Many people who downloaded this app did so because of the positive comments. After inviting people to Google+, I shared a post with them, asking if they could spend a few moments to post about their experience on the Android Market page. I learned later that many people thought the app was a scam based on the description, but were won over by the dozens of happy users posting positive comments.

Relatively few installs are needed to drive rankings
My app had only got 6,000 odd installs in a few days when it started to hit the trending charts. These aren’t really big numbers, so it doesn’t take a lot to become a trending or “hot” app. Once you’ve got that rank, it can become self-perpetuating and drive even more downloads.

Don’t copy other people’s stuff
It seems obvious – but don’t copy Google’s (or anyone else’s) trademarks or logos. Even for a short-term experiment. It might seem tempting to piggy-back off the success of a popular name, but it’s not worth the risk. Big corporations don’t understand, even if you’re “trying to do the right thing”.

New Editing Features in Eclipse plug-in for Android

2011-09-26T06:27:00.000-07:00

At the Google I/O conference a month ago, we demonstrated the next version of the Android Development Tools (ADT) plugin. Today we’re happy to announce that version 11 is done and available for download!

ADT 11 focuses on editor improvements. First, it offers several new visual refactoring operations, such as “Extract Include” and “Extract Style,” which help automatically extract duplicated layout fragments and style attributes into reusable layouts, styles, and themes.

Second, the visual layout editor now supports fragments, palette configurations, and improved support for custom views.

Last, XML editing has been improved with new quick fixes, code completion in more file types and many “go to declaration” enhancements.

ADT 11 packs a long list of new features and enhancements. Please visit our ADT page for more details. For an in-depth demo, check out the video of our Android Development Tools session at Google I/O, below.

Please note that the visual layout editor depends on a layout rendering library that ships with each version of the platform component in the SDK. We are currently working on a number of improvements to this library as well, which we plan to release soon for all platform versions. When we release the updates, some new features in ADT 11 will be “unlocked” - such as support for ListView previewing - so keep an eye on this blog for further announcements.