hacks-on-android-java-php-ios-flash

Implement Arxan GaurdIt protection for Android application having library project

2014-12-17T22:39:00.000-08:00

If you are stuck with Arxan protection for an Android application having library project please see few steps below

1. Edit Gaurdspec.gsml like ..

<target> <pair> <input>bin/classes</input> <output>bin/guardit4j/protectedclasses</output> </pair> <pair> <input>../library/bin/classes.jar</input> <output>bin/guardit4j/protectedlibs/classes.jar</output> </pair></target>

Add pairs for all the library project along with all the jars from lib folder. If you have 3 library project and each of them are using another 3rdparty jars resides in the respective libs folder add that as a pair also.

2. Add the lines below in gaurd4jrules.xml to marge all the library project into a single obfuscated.jar

 <jar destfile="${guardit4j.dir}/obfuscated.jar"> <fileset dir="${guardit4j.protected.dir}"/> <zipfileset includes="**/*" src="${guardit4j.dir}/protectedlibs/classes.jar"/>
</jar>  <path id="out.dex.jar.input.ref"/>

3. If you are using Gson library then modify gaurd4j.bat and append "-DKeepSignatures" with the java command.

For further help please fill free to contact me.

ant: warning: unmappable character for encoding UTF8

2014-12-17T21:24:00.001-08:00

During Jenkins implementation I have to configure my Android application using Ant build, but I have got warning like "ant: warning: unmappable character for encoding UTF8". Which is anyway build the entire application and create the APK file, but when I run the application it displays "?" instead of "€". Then I have been searching though Google, got many answers but none of them solve my problem. Then I figured out it is the Eclipse setting I have overlooked :-).

The code snippet I am getting this issue is given below

String EURO_SYMBOL = "€";

So what happened, when I have copy pasted the "€" sign then my Eclipse project setup for "Text File Encoding" was "Cp1252". So "€" got converted to "Cp1252" automatically. But default encoding for Ant was "UTF-8", so during compilation Ant try to convert all the files to "UTF-8" , which caused a junk character like "?" has been introduced.

To overcome this first I have to change my "Text File Encoding" to "UTF-8" and then I copy pasted "€" again to the line above and it solve my purpose.

Please add your comments if you still getting the warning.

Auto Generated "Data Model" using MSSQL server for Android ORMLite

2012-12-25T22:56:00.003-08:00

This is really hectic to create "Data Model" for each table where there are more than 50 tables in the database. I did search in Google but couldn't find such off the self solution. So I have dig down examples from different source add some extra flavor and created this tutorial . Here is a bare bone structure.

Though I have done this as per my requirement, but you can modify this as per your needs.
Main.Java

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

public class Main {
    public static void main(String[] args) throws Exception {
        HashMap<String,String> dataType = new HashMap<String,String>();
        dataType.put("bit","boolean");
        dataType.put("numeric","int");
        dataType.put("bigint","int");
        dataType.put("nchar","String");
        dataType.put("int","int");
        dataType.put("datetime","Date");
        dataType.put("smallint","int");
        dataType.put("nvarchar","String");
        dataType.put("timestamp","Timestamp");


        ArrayList<Table> tblArray = new ArrayList<Table>();
        String userName = "[username]";
        String password = "[password]";

        String url = "jdbc:sqlserver:[server path];databaseName=[database name]";

        Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
        Connection m_Connection = DriverManager.getConnection(url, userName,
                password);

        Statement m_Statement = m_Connection.createStatement();
        String query = "SELECT * FROM sys.Tables";

        ResultSet m_ResultSet = m_Statement.executeQuery(query);

        while (m_ResultSet.next()) {
            Table tbl = new Table();
            tbl.tableName = m_ResultSet.getString(1);
            if(!"sysdiagrams".equals(tbl.tableName))
                tblArray.add(tbl);
        }

        for (Table tbl : tblArray) {

            // System.out.println("retrieved element: " + tbl.tableName);
            String queryBasicTableInfoWithPK = "Select C.COLUMN_NAME, C.DATA_TYPE, Case When Z.CONSTRAINT_NAME Is "
                    + "Null Then 0 Else 1 End As IsPartOfPrimaryKey From INFORMATION_SCHEMA.COLUMNS "
                    + "As C Outer Apply (Select CCU.CONSTRAINT_NAME   From INFORMATION_SCHEMA.TABLE_CONSTRAINTS "
                    + "As TC Join INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE As CCU On "
                    + "CCU.CONSTRAINT_NAME = TC.CONSTRAINT_NAME   Where TC.TABLE_SCHEMA = C.TABLE_SCHEMA "
                    + "And TC.TABLE_NAME = C.TABLE_NAME   And TC.CONSTRAINT_TYPE = 'PRIMARY KEY' "
                    + "And CCU.COLUMN_NAME = C.COLUMN_NAME ) As Z Where C.TABLE_NAME = '"
                    + tbl.tableName + "'";

            ResultSet queryBasicTableInfoWithPK_ResultSet = m_Statement
                    .executeQuery(queryBasicTableInfoWithPK);
            while (queryBasicTableInfoWithPK_ResultSet.next()) {
                // System.out.println(queryBasicTableInfoWithPK_ResultSet.getString(1)+"::"+queryBasicTableInfoWithPK_ResultSet.getString(2)+"::"+queryBasicTableInfoWithPK_ResultSet.getString(3));
                tbl.hm.put(queryBasicTableInfoWithPK_ResultSet.getString(1),
                        queryBasicTableInfoWithPK_ResultSet.getString(2));

                if (queryBasicTableInfoWithPK_ResultSet.getString(3)
                        .equals("1")) {
                    tbl.pk = queryBasicTableInfoWithPK_ResultSet.getString(1);

                }
            }
            queryBasicTableInfoWithPK_ResultSet.close();
        }

        for (Table tbl : tblArray) {
            //System.out.print("retrieved element: " + tbl.tableName);
            Set set = tbl.hm.entrySet();
            // Get an iterator
            Iterator i = set.iterator();
            // Display elements
            while (i.hasNext()) {
                Map.Entry me = (Map.Entry) i.next();
                //                if (me.getKey().equals(tbl.pk))
                //                    System.out.println("=> Primary Key ::: " + tbl.pk);
                //                System.out.print(me.getKey() + ": ");
                //                System.out.println(me.getValue());

                String queryBasicTableInfoWithFK = "SELECT    PK_Table = PK.TABLE_NAME FROM    INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS "
                        + "C INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK    ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME INNER JOIN "
                        + "INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK    ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME INNER JOIN "
                        + "INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU    ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME INNER JOIN (            "
                        + "SELECT                i1.TABLE_NAME,                i2.COLUMN_NAME            FROM                "
                        + "INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1            INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2                "
                        + "ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME            WHERE                i1.CONSTRAINT_TYPE = 'PRIMARY KEY'           "
                        +") PT    ON PT.TABLE_NAME = PK.TABLE_NAME    WHERE FK.TABLE_NAME = '"+tbl.tableName+"' and "
                        +"CU.COLUMN_NAME = '"+me.getKey()+"'";

                ResultSet queryBasicTableInfoWithFK_ResultSet = m_Statement
                        .executeQuery(queryBasicTableInfoWithFK);
                while (queryBasicTableInfoWithFK_ResultSet.next()) {
                    i.remove();
                    tbl.hmFK.put(queryBasicTableInfoWithFK_ResultSet.getString(1),"FK");
                    //System.out.println("FK Table Name "+queryBasicTableInfoWithFK_ResultSet.getString(1));
                }

                queryBasicTableInfoWithFK_ResultSet.close();

            }
        }

        for (Table tbl : tblArray) {
            System.out.println("retrieved element: " + tbl.tableName);

            String headerPart = "package com.android.syngenta.db.dao; \r\n";

            headerPart += "import java.io.Serializable; \r\n";

            headerPart += "import java.sql.Timestamp; \r\n";

            headerPart +="import java.sql.Date; \n\r";

            headerPart +="import com.j256.ormlite.field.DatabaseField; \r\n";
            headerPart +="import com.j256.ormlite.table.DatabaseTable; \r\n";

            headerPart +="\r\n \r\n";

            headerPart +="@DatabaseTable \r\n";
            headerPart +="public class "+tbl.tableName+" implements Serializable \r\n";
            headerPart +="{ \r\n";

            headerPart +="\r\n \r\n";
            headerPart +="private static final long serialVersionUID = 1L; \r\n";
            headerPart +="\r\n \r\n";

            Set set = tbl.hm.entrySet();
            // Get an iterator
            Iterator i = set.iterator();
            System.out.println("Column: ");
            while (i.hasNext()) {
                Map.Entry me = (Map.Entry) i.next();
                if (me.getKey().equals(tbl.pk))
                {
                    System.out.println("=> Primary Key ::: " + tbl.pk);
                    if(dataType.get(me.getValue()).equalsIgnoreCase("String"))
                        headerPart +="@DatabaseField (id = true) \r\n";
                    else
                        headerPart +="@DatabaseField (generatedId = true) \r\n";

                    headerPart +="public "+dataType.get(me.getValue())+" "+me.getKey()+"; \r\n";
                    headerPart +="\r\n \r\n";
                }
                else
                {
                    headerPart +="@DatabaseField \r\n";
                    headerPart +="public "+dataType.get(me.getValue())+" "+me.getKey()+"; \r\n";
                    headerPart +="\r\n \r\n";
                }
                System.out.print(me.getKey() + ": ");
                System.out.println(me.getValue());
            }

            Set setFK = tbl.hmFK.entrySet();
            // Get an iterator
            Iterator iFK = setFK.iterator();
            System.out.println("Column FK: ");
            while (iFK.hasNext()) {
                Map.Entry me = (Map.Entry) iFK.next();
                System.out.print(me.getKey() + ": ");
                System.out.println(me.getValue());
                String tblname = (String) me.getKey();
                headerPart +="@DatabaseField (foreign = true) \r\n";
                headerPart +="public "+me.getKey()+" "+Character.toLowerCase(tblname.charAt(0)) + tblname.substring(1)+"; \r\n";
                headerPart +="\r\n \r\n";
            }
            System.out.println("============================");

            headerPart +="}";

            FileWriter fileWriter = null;
            try {
                File newTextFile = new File("./dao/"+tbl.tableName+".java");
                fileWriter = new FileWriter(newTextFile);
                fileWriter.write(headerPart);
                fileWriter.close();
            } catch (IOException ex) {
                // Logger.getLogger(WriteStringToFile.class.getName()).log(Level.SEVERE,
                // null, ex);
            } finally {
                try {
                    if(fileWriter != null)
                        fileWriter.close();
                } catch (IOException ex) {
                    // Logger.getLogger(WriteStringToFile.class.getName()).log(Level.SEVERE,
                    // null, ex);
                }
            }
        }
    }
}

Table.java

import java.util.HashMap;

public class Table {
    String tableName;
    HashMap hm = new HashMap();
    HashMap hmFK = new HashMap();
    String pk;
}

Hope this helps.

Android Best Practices

2012-05-15T02:16:00.000-07:00

1. Android Coding Convention

1.1 Don’t Ignore Exception

void setServerPort(String value) {

try {

serverPort = Integer.parseInt(value);

} catch (NumberFormatException e) { }

}

1.2 Don’t Catch Generic Exception

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!

}

1.3 Fully Qualify Imports

When you want to use class Bar from package foo,there are two possible ways to import it:

import foo.*;

Pros: Potentially reduces the number of import statements.

import foo.Bar;

Pros: Makes it obvious what classes are actually used. Makes code more readable for maintainers.

Decision: Use the latter for importing all Android code. An explicit exception is made for java standard libraries (java.util.*, java.io.*, etc.) and unit test code (junit.framework.*)

1.4 Use Javadoc Standard Comments

/** 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

public String(byte[] bytes) {

}

1.5 Conventions that Don’t Hurt [No harm in following them, but their value is questionable]Put Open Braces with Preceding Code.

Yes

public void foo() {

if (...) {

doSomething();

}

public void foo()

{

if (...)

{

doSomething();

}

1.6 Use Spaces For Indentation

We use 8 space indents for line wraps, including function calls and assignments. For example,

this is correct:

Instrument i =

someLongExpression(that, wouldNotFit, on, one, line);

and this is not correct:

Instrument i =

someLongExpression(that, wouldNotFit, on, one, line);

1.7 Follow Filed Naming Convention

Non-public, non-static field names start with m.

Static field names start with s.

Other fields start with a lower case letter.

Public static final fields (constants) are ALL_CAPS_WITH_UNDERSCORES.

public class MyClass {

public static final int SOME_CONSTANT = 42;

public int publicField;

private static MyClass sSingleton;

int mPackagePrivate;

}//A class following Field Naming Conventions

1.8 Treat Acronyms as Words

Treat acronyms and abbreviations as words in naming variables, methods, and classes. The names are much more readable:

Good Bad

XmlHttpRequest XMLHTTPRequest

getCustomerId getCustomerID

class Html class HTML

String url String URL

long id long ID

1.9 Use TODO Comments

2. The Golden Rules of Performance

• Don't do work that you don't need to do

• Don't allocate memory if you can avoid it

2.1 Performance Pointers

2.1.1 Avoid creating objects

Object creation is never free. A generational GC with per-thread allocation pools for temporary objects can make allocation cheaper, but allocating memory is always more expensive than not allocating memory.

If you allocate objects in a user interface loop, you will force a periodic garbage collection, creating little "hiccups" in the user experience. The concurrent collector introduced in Gingerbread helps, but unnecessary work should always be avoided.

Thus, you should avoid creating object instances you don't need to. Some examples of things that can help:

If you have a method returning a string, and you know that its result will always be appended to a StringBuffer anyway, change your signature and implementation so that the function does the append directly, instead of creating a short-lived temporary object.
When extracting strings from a set of input data, try to return a substring of the original data, instead of creating a copy. You will create a new String object, but it will share the char[] with the data. (The trade-off being that if you're only using a small part of the original input, you'll be keeping it all around in memory anyway if you go this route.)

A somewhat more radical idea is to slice up multidimensional arrays into parallel single one-dimension arrays:

An array of ints is a much better than an array of Integers, but this also generalizes to the fact that two parallel arrays of ints are also a lot more efficient than an array of (int,int) objects. The same goes for any combination of primitive types.
If you need to implement a container that stores tuples of (Foo,Bar) objects, try to remember that two parallel Foo[] and Bar[] arrays are generally much better than a single array of custom (Foo,Bar) objects. (The exception to this, of course, is when you're designing an API for other code to access; in those cases, it's usually better to trade good API design for a small hit in speed. But in your own internal code, you should try and be as efficient as possible.)

Generally speaking, avoid creating short-term temporary objects if you can. Fewer objects created mean less-frequent garbage collection, which has a direct impact on user experience.

2.1.2 Prefer Static Over Virtual

If you don't need to access an object's fields, make your method static. Invocations will be about 15%-20% faster. It's also good practice, because you can tell from the method signature that calling the method can't alter the object's state.

2.1.3 Avoid Internal Getters/ Setters

In native languages like C++ it's common practice to use getters (e.g. i = getCount()) instead of accessing the field directly (i = mCount). This is an excellent habit for C++, because the compiler can usually inline the access, and if you need to restrict or debug field access you can add the code at any time.

On Android, this is a bad idea. Virtual method calls are expensive, much more so than instance field lookups. It's reasonable to follow common object-oriented programming practices and have getters and setters in the public interface, but within a class you should always access fields directly.

2.1.4 Use Static Final For Constants

Consider the following declaration at the top of a class:

static int intVal = 42;
static String strVal = "Hello, world!";

The compiler generates a class initializer method, called <clinit>, that is executed when the class is first used. The method stores the value 42 into intVal, and extracts a reference from the classfile string constant table for strVal. When these values are referenced later on, they are accessed with field lookups.

We can improve matters with the "final" keyword:

static final int intVal = 42;
static final String strVal = "Hello, world!";

The class no longer requires a <clinit> method, because the constants go into static field initializers in the dex file. Code that refers to intVal will use the integer value 42 directly, and accesses to strVal will use a relatively inexpensive "string constant" instruction instead of a field lookup. (Note that this optimization only applies to primitive types and String constants, not arbitrary reference types. Still, it's good practice to declare constants static final whenever possible.)

2.1.5 Use Enhanced For Loop Syntax

The enhanced for loop (also sometimes known as "for-each" loop) can be used for collections that implement the Iterable interface and for arrays. With collections, an iterator is allocated to make interface calls to hasNext() and next(). With an ArrayList, a hand-written counted loop is about 3x faster (with or without JIT), but for other collections the enhanced for loop syntax will be exactly equivalent to explicit iterator usage.
There are several alternatives for iterating through an array:

    static class Foo {

        int mSplat;

    }

    Foo[] mArray = ...



    public void zero() {

        int sum = 0;

        for (int i = 0; i < mArray.length; ++i) {

            sum += mArray[i].mSplat;

        }

    }



    public void one() {

        int sum = 0;

        Foo[] localArray = mArray;

        int len = localArray.length;



        for (int i = 0; i < len; ++i) {

            sum += localArray[i].mSplat;

        }

    }



    public void two() {

        int sum = 0;

        for (Foo a : mArray) {

            sum += a.mSplat;

        }

    }

zero() is slowest, because the JIT can't yet optimize away the cost of getting the array length once for every iteration through the loop.
one() is faster. It pulls everything out into local variables, avoiding the lookups. Only the array length offers a performance benefit.
two() is fastest for devices without a JIT, and indistinguishable from one() for devices with a JIT. It uses the enhanced for loop syntax introduced in version 1.5 of the Java programming language.
To summarize: use the enhanced for loop by default, but consider a hand-written counted loop for performance-critical ArrayList iteration.

2.1.6 Consider Package Instead Of Private Access With Private Inner Classes

Consider the following class definition:

public class Foo {

    private class Inner {

        void stuff() {

            Foo.this.doStuff(Foo.this.mValue);

        }

    }



    private int mValue;



    public void run() {

        Inner in = new Inner();

        mValue = 27;

        in.stuff();

    }



    private void doStuff(int value) {

        System.out.println("Value is " + value);

    }

}

The key things to note here are that we define a private inner class (Foo$Inner) that directly accesses a private method and a private instance field in the outer class. This is legal, and the code prints "Value is 27" as expected.
The problem is that the VM considers direct access to Foo's private members from Foo$Inner to be illegal because Foo and Foo$Inner are different classes, even though the Java language allows an inner class to access an outer class' private members. To bridge the gap, the compiler generates a couple of synthetic methods:

/*package*/ static int Foo.access$100(Foo foo) {

    return foo.mValue;

}

/*package*/ static void Foo.access$200(Foo foo, int value) {

    foo.doStuff(value);

}

The inner class code calls these static methods whenever it needs to access the mValue field or invoke the doStuff method in the outer class. What this means is that the code above really boils down to a case where you're accessing member fields through accessor methods. Earlier we talked about how accessors are slower than direct field accesses, so this is an example of a certain language idiom resulting in an "invisible" performance hit.
If you're using code like this in a performance hotspot, you can avoid the overhead by declaring fields and methods accessed by inner classes to have package access, rather than private access. Unfortunately this means the fields can be accessed directly by other classes in the same package, so you shouldn't use this in public API.

2.1.7 Know And Use The Library

In addition to all the usual reasons to prefer library code over rolling your own, bear in mind that the system is at liberty to replace calls to library methods with hand-coded assembler, which may be better than the best code the JIT can produce for the equivalent Java. The typical example here is String.indexOf and friends, which Dalvik replaces with an inlined intrinsic. Similarly, the System.arraycopy method is about 9x faster than a hand-coded loop on a Nexus One with the JIT.

2.2 Responsiveness

Avoid modal Dialogues and Activities

• Always update the user on progress (ProgressBar and

ProgressDialog)

• Render the main view and fill in data as it arrives

"Application Not Responding"

• Respond to user input within 5 seconds

• Broadcast Receiver must complete in 10 seconds

Users perceive a lag longer than 100 to 200ms

Use Threads and AsyncTasks within Services

2.3 Gluttony

2.3.1 Don'ts

• DON'T over use WakeLocks

• DON'T update Widgets too frequently

• DON'T update your location unnecessarily

• DON'T use Services to try to override users or the system

2.3.2 Dos

• DO share data to minimize duplication

• DO use Receivers and Alarms not Services and Threads

• DO let users manage updates

• DO minimize resource contention

2.3.3 What is a WakeLock?

· Force the CPU to keep running

· Force the screen to stay on (or stay bright)

· Drains your battery quickly and efficiently

PowerManager pm =

(PowerManager)getSystemService(Context.POWER_SERVICE);

PowerManager.WakeLock wl =

pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK,

"My Wakelock");

wl.acquire();

// Screen and power stays on

wl.release();

2.3.4 Using WakeLocks

• Do you really need to use one?

• Use the minimum level possible

o PARTIAL_WAKE_LOCK

o SCREEN_DIM_WAKE_LOCK

o SCREEN_BRIGHT_WAKE_LOCK

o FULL_WAKE_LOCK

• Release as soon as you can

• Specify a timeout

• Don't use them in Activities

2.3.5 Window Managed WakeLocks

· No need for permissions

· No accidently leaving the screen from the background

getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

2.4 Hostility

2.4.1 User experience should be your top priority

2.4.2 Respect user expectations for navigating your app

· The back button should always navigate back through previously seen screens

· Always support trackball navigation

· Understand your navigation flow when entry point is anotification or widget

· Navigating between application elements should be easy and intuitive

2.4.3 Don't hijack the native experience

· Don't hide the status bar

· Back button should always navigate through previous screens

· Use native icons consistently

· Don't override the menu button

· Put menu options behind the menu button

2.4.4 Respect user preferences

• Use only enabled location-based services

• Ask permission before transmitting location data

• Only transfer data in the background if user enabled

ConnectivityManager cm = (ConnectivityManager)

getSystemService(Context.CONNECTIVITY_SERVICE);

boolean backgroundEnabled = cm.getBackgroundDataSetting();

2.5 Arrogance

• Don't use undocumented APIs

• Make your app behave consistently with the system

• Respect the application lifecycle model

• Support both landscape and portrait modes

• Don't disable rotation handling

2.6 Size Discrimination

· Don't make assumptions about screen size or resolution

· Use Relative Layouts and device independent pixels

· Optimize assets for different screen resolutions

2.7 Ensuring Future Hardware Happiness

· Specify uses-feature node for every API you use.

· Mark essential features as required.

· Mark optional features as not required.

<uses-feature

android:name="android.hardware.location"

android:required="true"/>

<uses-feature

android:name="android.hardware.location.network"

android:required="false"/>

<uses-feature

android:name="android.hardware.location.gps" android:required="false"/>

· Check for API existence in code.

PackageManager pm = getPackageManager();

boolean hasCompass =

pm.hasSystemFeature(

PackageManager.FEATURE_SENSOR_COMPASS);

if (hasCompass) {

// Enable things that require the compass.

}

3. The Five Glorious Virtues

3.1 Beauty

• Create assets optimized for all screen resolutions

o Start with vectors or high-res raster art

o Scale down and optimize for supported screen

• Support resolution independence

• Use tools to optimize your implementation

o layoutopt

o hierarchyviewer

3.2 Generosity

3.2.1 Use Intents to leverage other people's apps

• Works just like your own Activity

• Can pass data back and forth between applications

• Return to your Activity when closed

String action = "com.hotelapp.ACTION_BOOK";

String hotel = "hotel://name/" + selectedhotelName;

Uri data = Uri.parse(hotel);

Intent bookingIntent = new Intent(action, data);

startActivityForResult(bookingIntent);

3.2.2 Define Intent Filters to share your functionality

• Indicate the ability to perform an action on data

• Specify an action you can perform

• Specify the data you can perform it on

<activity android:name="Booking" android:label="Book">

<intent-filter>

<action android:name="com.hotelapp.ACTION_BOOK" />

<data android:scheme="hotel"

android:host="name"/>

</intent-filter>

</activity>

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(r.layout.main);

Intent intent = getIntent();

String action = intent.getAction();

Uri data = intent.getData();

String hotelName = data.getPath();

// TODO Provide booking functionality

setResult(RESULT_OK, null);

finish();

}

3.3 Ubiquity

• Create widgets

• Surface search results into the Quick Search Box

• Live Folders

• Live Wallpapers

• Expose Intent Receivers to share your functionality

• Fire notifications

3.4 Utility & Entertainment

• Create an app that solves a problem

• Present information in the most useful way possible

• Create games that are ground breaking and compelling

4. What we should do and don’t

4.1 Let the runtime kill your background Service

4.1.1 For Services that perform a single action / polling

4.1.2 Reduces resource contention

@Override

public int onStartCommand(Intent intent, int f, int sId) {

handleCommand(intent);

return START_NOT_STICKY;

}

@Override

public void onStart(Intent intent, int sId) {

handleCommand(intent);

}

4.1.3 Kill your own Service

@Override

public int onStartCommand(Intent i, int f, int sId) {

myTask.execute();

return Service.START_NOT_STICKY;

}

AsyncTask<Void, Void, Void> myTask =

new AsyncTask<Void, Void, Void>() {

@Override

protected Void doInBackground(Void... arg0) {

// TODO Execute Task

return null;

}

@Override

protected void onPostExecute(Void result) {

stopSelf();

}

};

4.2 Use Alarms and Intent Receivers

• Schedule updates and polling

• Listen for system or application events

• No Service. No Activity. No running Application.

4.2.1 Intent Receivers

<intent-filter>

<action android:name="REFRESH_THIS" />

</intent-filter>

</receiver>

public class MyReceiver extends BroadcastReceiver {

@Override

public void onReceive(Context context, Intent i) {

Intent ss = new Intent(context, MyService.class);

context.startService(ss);

}

4.2.2 Alarms

4.2.3 Use inexact Alarms

• All the Alarm goodness

• Now with less battery drain!

int type = AlarmManager.ELAPSED_REALTIME_WAKEUP;

long interval = AlarmManager.INTERVAL_FIFTEEN_MINUTES;

long triggerTime = SystemClock.elapsedRealtime() +

interval;

am.setInexactRepeating(type, triggerTime,interval, op);

4.3 Location Based Services

String serviceName = Context.LOCATION_SERVICE;

lm = LocationManager)getSystemService(serviceName);

LocationListener l = new LocationListener() {

public void onLocationChanged(Location location) {

// TODO Do stuff when location changes!

}

public void onProviderDisabled(String p) {}

public void onProviderEnabled(String p) {}

public void onStatusChanged(String p, int s, Bundle e) {}

};

lm.requestLocationUpdates("gps", 0, 0, l);

• How often do you need updates?

• What happens if GPS or Wifi LBS is disabled?

• How accurate do you need to be?

• What is the impact on your battery life?

• What happens if location 'jumps'?

4.3.1 Restricting Updates

• Specify the minimum update frequency

• Specify the minimum update distance

int freq = 5 * 60000; // 5mins

int dist = 1000; // 1000m

lm.requestLocationUpdates("gps", freq, dist, l);

4.3.2 Use Criteria to Select a Location Provider

Criteria criteria = new Criteria();

criteria.setPowerRequirement(Criteria.POWER_LOW);

criteria.setAccuracy(Criteria.ACCURACY_FINE);

criteria.setAltitudeRequired(false);

criteria.setBearingRequired(false);

criteria.setSpeedRequired(false);

criteria.setCostAllowed(false);

String provider = lm.getBestProvider(criteria, true);

lm.requestLocationUpdates(provider, freq, dist, l);

• Specify your requirements and preferences

o Allowable power drain

o Required accuracy

o Need for altitude, bearing, and speed

o Can a cost be incurred?

• Find the best provider that meets your criteria

• Relax criteria (in order) until a provider is found

• Can limit to only active providers

• Can use to find all matching providers

4.3.3 Implement a Back-off Pattern

• Use multiple Location Listeners

o Fine and coarse

o High and low frequency / distance

• Remove listeners as accuracy improves

Location Based Services

lm.requestLocationUpdates(coarseProvider,0,0, lcourse);

lm.requestLocationUpdates(fineProvider, 0, 0, lbounce);

private LocationListener lbounce = new LocationListener(){

public void onLocationChanged(Location location) {

runLocationUpdate();

if (location.getAccuracy() < 10) {

lm.removeUpdates(lbounce);

lm.removeUpdates(lcoarse);

lm.requestLocationUpdates(provider, freq, dist, l);

}

};

private LocationListener lcoarse = new LocationListener(){

public void onLocationChanged(Location location) {

runLocationUpdate();

lm.removeUpdates(lcoarse);

}

};

5. Static Analysis Tools

TestNG : http://testng.org/doc/index.html

http://pmd.sourceforge.net/pmd-5.0.0/

Progressbar is not showing with background process

2012-05-15T02:11:00.000-07:00

For one of my project I had a long running process prior to display root activity but somehow I couldn't been able to display the progressbar properly. Thee gone through some of the firum and I found this as a rendering problem. Due to CPU bounded process UI renderer stops rendering. So somehow I need to stop the other process prior to display the progress bar. For that I have used thread with postdelay, here is a pseudo code

ProgressBar.visibility=View.VISIBLE;

MyHandler.postDelayed(new Runnable() {
public void run() {
   //Move all the code here.

     ProgressBar.visibility=View.GONE;

 }
                    }, 3000);

So now my progress bar got 3000 ms to display itself in the view holder.

Hope this help to save someone's time :-)

Display random number around a circular image

2011-12-20T20:59:00.000-08:00

Bitmap bonuswheel = loadImage(R.drawable.bonuswheel);
Bitmap bmOverlay = bonuswheel.copy(Bitmap.Config.ARGB_8888, true);
// create a canvas on which to draw
Paint bonusspinnerFont = setFontProperties("fonts/MyriadWebPro-Bold.ttf", 255, 0, 0, 0, 20, false, 2);
Canvas canvas = new Canvas(bmOverlay);
Random randomGenerator = new Random();
for(int a=0;a<18;a++)
{
bonus_array[a] = a;//*randomGenerator.nextInt(100);
Log.v("COMPAIR",""+bonus_array[a]);
}
for(int a=0;a<18;a++)
{
canvas.drawText(""+bonus_array[a], 60, bonuswheel.getHeight()/2 , bonusspinnerFont);
canvas.rotate(20, bonuswheel.getWidth()/2, bonuswheel.getHeight()/2);
}

How to increase Flash Performance

2011-10-14T12:01:00.000-07:00

Taken from
http://www.anandvardhan.com/2007/06/27/flex-performance-tuning-tips/

If you have a type in AS3, which you are not sure of always use the As operator to cast the type before you use it. This avoids VM errors with try/catch, which slow the execution and is ten times slower than the As operator.
Array is access is slow if the array is sparse. It may be faster to put nulls in empty values as this speeds things up. Array misses are very slow, up to 20 times slower than finding a valid entry.

Avoid implicit type conversion. In the player it will convert integers to numbers and back when asked to add integers. You might as well use numbers for everything and convert back to integer at the end.

Local variable access is faster, so assign variables to local if they are accessed a lot. They will be stored on the stack and access is much quicker.
Data Binding expressions take up memory and can slow down the application startup. It may be more efficient to do an assignment in code rather than using binding.

Find a slow computer and run your application. If it runs OK ship it! Other wise you can use flash.utils.getTimer():int to get a time value in miliseconds before and after some process to time it.

In Flex Builder 3 there is a profiler that allows you to take performance snapshots to record how long was spent in each function. This is useful to identify the areas of code that might benefit from optimization. While profiler is running everything is much slower. Often Mouse or similar Events will seem to take lots of time, you can ignore these. Investigate your own functions and see if they have been called too often or they take too long.

Create password protected file in android

2011-08-05T08:11:00.000-07:00

package com.cz.util;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Properties;
import java.util.Random;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

import android.util.Log;

public class FileEncryptorDecryptor
{

private static String filename;
private static FileInputStream inFile;
private static FileOutputStream outFile;

public void encrypt(FileInputStream filename, FileOutputStream outFile,String password) throws Exception
{
inFile = filename;

// Use PBEKeySpec to create a key based on a password.
// The password is passed as a character array

PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray());
SecretKeyFactory keyFactory =
SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey passwordKey = keyFactory.generateSecret(keySpec);

// PBE = hashing + symmetric encryption. A 64 bit random
// number (the salt) is added to the password and hashed
// using a Message Digest Algorithm (MD5 in this example.).
// The number of times the password is hashed is determined
// by the interation count. Adding a random number and
// hashing multiple times enlarges the key space.

byte[] salt = new byte[8];
Random rnd = new Random();
rnd.nextBytes(salt);
int iterations = 100;

//Create the parameter spec for this salt and interation count

PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, iterations);

// Create the cipher and initialize it for encryption.

Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
cipher.init(Cipher.ENCRYPT_MODE, passwordKey, parameterSpec);

// Need to write the salt to the (encrypted) file. The
// salt is needed when reconstructing the key for decryption.

outFile.write(salt);

// Read the file and encrypt its bytes.

byte[] input = new byte[64];
int bytesRead;
while ((bytesRead = inFile.read(input)) != -1)
{
byte[] output = cipher.update(input, 0, bytesRead);
if (output != null) outFile.write(output);
}

byte[] output = cipher.doFinal();
if (output != null) outFile.write(output);

inFile.close();
outFile.flush();
outFile.close();

}

public void decrypt(FileInputStream filename, FileOutputStream outFile,String password) throws Exception
{
inFile = filename;

PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray());
SecretKeyFactory keyFactory =
SecretKeyFactory.getInstance("PBEWithMD5AndDES");
SecretKey passwordKey = keyFactory.generateSecret(keySpec);

// Read in the previouly stored salt and set the iteration count.

byte[] salt = new byte[8];
inFile.read(salt);
int iterations = 100;

PBEParameterSpec parameterSpec = new PBEParameterSpec(salt, iterations);

// Create the cipher and initialize it for decryption.

Cipher cipher = Cipher.getInstance("PBEWithMD5AndDES");
cipher.init(Cipher.DECRYPT_MODE, passwordKey, parameterSpec);

byte[] input = new byte[64];
int bytesRead;
while ((bytesRead = inFile.read(input)) != -1)
{
byte[] output = cipher.update(input, 0, bytesRead);
if (output != null)
outFile.write(output);
}

byte[] output = cipher.doFinal();
if (output != null)
outFile.write(output);

inFile.close();
outFile.flush();
outFile.close();
}

}

android load on startup service

2011-07-19T04:48:00.000-07:00

Most of the time user needs to start a application on boot up, which needs to be auto start. I have searched a lot but didn;t find a good tutorial, but somehow I have managed it and it is working in my My Touch phone. Step to follow

1. Manifest FIle
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.events">
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.WRITE_CALENDAR" />
<uses-permission android:name="android.permission.READ_CALENDAR" />
<uses-permission android:name="android.permission.VIBRATE" />
<application>
<receiver android:name=".MyBroadcastreceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
<service android:name=".MyService" />
</application>
</manifest>

2. Receiver

package com.android.events;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class MyBroadcastreceiver extends BroadcastReceiver {
public static final String TAG = "Rajesh";

@Override
public void onReceive(Context context, Intent intent) {

if ("android.intent.action.BOOT_COMPLETED".equals(intent.getAction())) {
Intent pushIntent = new Intent(context, MyService.class);
context.startService(pushIntent);
}
}

}

3. MyService.class could be anything which extends Service

Hope this will help you :-)

Check Google PR / Page Ranking For Multiple Domain Name

2011-07-13T03:51:00.000-07:00

If you want to use a drop domain catcher script which could register only those domain which have Google Page Rank more than 3, then you might need a script like this example Google Page Rank Checker For Multiple Domain . Please upload only a text file, having domian names, followed by new line.

Problem with MergeList /var/lib/apt/lists/us.archive.ubuntu.com_ubuntu_dists_natty_multiverse_binary-amd64_Packages

2011-07-12T02:47:00.000-07:00

Check the solution Here.

Android Chart Library

2011-07-10T06:58:00.000-07:00

After googling I have found a good chart engine for android. Really good library to go ahead. I am thinking to donate something for him. First let me create a single project with this library and see if there is any flaw. But at a glance they did well. Please follow this link Android Chart Library

Create a xml based family tree using Actionscript3

2011-07-05T08:58:00.000-07:00

I haven't got a good flow chart creator tools in actionscript3, so I have started working on this myself and thought to share the code with you guys. So far I have been able to got some time to create a prototype of this and obviously a dirty code. Also here is a screen capture of the same. If you need the source code please drop me a mail at rajeshghosh1978@gmail.com.

How to draw an elastic line having circle at both end

2011-07-05T08:47:00.000-07:00

If you are going to create a flow diagram or a white board application, you might need a line which acts like an elastic string, where as user can drag both end. So I have created for one of my project and thought, it might help someone to save some time. Here are the classes

elasticLine.as

package com.collectivezen{
import flash.display.DisplayObject;
import flash.display.Graphics;
import flash.display.Shape;
import flash.display.Sprite;
import flash.display.MovieClip;
import com.collectivezen.RoundRectangle;

import flash.filters.*;

public class elasticLine extends MovieClip {
private var rrX:Number;
private var rrY:Number;
private var rrWidth:Number;
private var rrHeight:Number;
private var bgColor:uint;
private var borderColor:uint;
private var borderSize:Number;
private var child:MovieClip = new MovieClip();
private var src:RoundRectangle;
private var dest:RoundRectangle;
private var _this:elasticLine;
private var lineDrawing:MovieClip = new MovieClip();

public function elasticLine(rrX:Number=0,rrY:Number=0,rrWidth:Number=10,rrHeight:Number=10,bgColor:uint=0x000000) {
this.rrX=rrX;
this.rrY=rrY;
this.rrWidth=rrWidth;
this.rrHeight=rrHeight;
this.bgColor=bgColor;
lineDrawing = new MovieClip();
lineDrawing.graphics.lineStyle(1, 0x000000, 1 );
lineDrawing.graphics.beginFill( bgColor, 1 );
lineDrawing.graphics.moveTo(rrX,rrY);
lineDrawing.graphics.lineTo(rrWidth,rrHeight);

///Glow Filter
var glow:GlowFilter = new GlowFilter();
glow.color = bgColor;
glow.alpha = 1;
glow.blurX = 8;
glow.blurY = 8;

var dropShadow:DropShadowFilter = new DropShadowFilter();
dropShadow.color = 0x000000;
dropShadow.blurX = 8;
dropShadow.blurY = 8;
dropShadow.angle = 0;
dropShadow.alpha = 0.5;
dropShadow.distance = 10;

var filtersArray:Array = new Array(glow, dropShadow);
lineDrawing.filters = filtersArray;
addChild(lineDrawing);
}
public function moveLine(src:RoundRectangle,dest:RoundRectangle) {
lineDrawing.graphics.clear();
lineDrawing.graphics.lineStyle(1, 0x000000, 1 );
lineDrawing.graphics.beginFill( this.bgColor, 1 );
lineDrawing.graphics.moveTo(src._CurCenX,src._CurCenY);
lineDrawing.graphics.lineTo(dest._CurCenX,dest._CurCenY);

///Glow Filter
var glow:GlowFilter = new GlowFilter();
glow.color = this.bgColor;
glow.alpha = 1;
glow.blurX = 8;
glow.blurY = 8;

var dropShadow:DropShadowFilter = new DropShadowFilter();
dropShadow.color = 0x000000;
dropShadow.blurX = 8;
dropShadow.blurY = 8;
dropShadow.angle = 0;
dropShadow.alpha = 0.5;
dropShadow.distance = 10;

var filtersArray:Array = new Array(glow, dropShadow);
lineDrawing.filters = filtersArray;
}
public function drawLine(_X:uint,_Y:uint,_eX:uint,_eY:uint,_col:uint) {
lineDrawing.graphics.clear();
lineDrawing.graphics.lineStyle(1, 0x000000, 1 );
lineDrawing.graphics.beginFill( _col, 1 );
lineDrawing.graphics.moveTo(_X,_Y);
lineDrawing.graphics.lineTo(_eX,_eY);

///Glow Filter
var glow:GlowFilter = new GlowFilter();
glow.color = _col;
glow.alpha = 1;
glow.blurX = 8;
glow.blurY = 8;

var dropShadow:DropShadowFilter = new DropShadowFilter();
dropShadow.color = 0x000000;
dropShadow.blurX = 8;
dropShadow.blurY = 8;
dropShadow.angle = 0;
dropShadow.alpha = 0.5;
dropShadow.distance = 10;

var filtersArray:Array = new Array(glow, dropShadow);
lineDrawing.filters = filtersArray;
}

}
}

See my different post to get com.collectivezen.RoundRectangle

Steps to install new android application onto new htc device

2011-07-04T09:09:00.000-07:00

1. Unplug the device

2. $ sudo gedit /etc/udev/rules.d/99-android.rules
(Taking help from http://dimitar.me/how-to-connect-your-android-phone-to-ubuntu-to-do-developmenttestinginstallations-or-tethering/ the file name should be 51--android.rules
but 99 is the latest.

3. add these lines and save
SUBSYSTEM=="usb", ATTR{idVendor}=="04e8", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="0bb4", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0666"
SUBSYSTEM=="usb", ATTR{idVendor}=="1004", ATTR{idProduct}=="618e", MODE="0666"

4. Plug the device again.

5. If still doesn't work
$ adb kill-server
$ adb start-server

and do unplug and plug the device again.

Meteor Client JS doesn't work properly with Longpoll

2011-07-03T12:04:00.000-07:00

As per the documentation given in the meteor.org , longpolling should poll the server once there is an event. But it is not working that way. It polls the server for a scheduled interval, based on meteor.js configuration. Basically Javascript is doing the socket connection using XHR like an AJAX, but I don't think it acts like a real socket connection and which is the reason meteor JS client needs to poll server at a regular interval, which is fine, but it breaks the Meteor JS documentation. Also there are some issues in the current meteor release. From a low bandwidth internet connection , it trapped into poll timeout and it polls again and again, which is creating multiple response at a certain point of time, so as a result , same message is comming more than one time for a given registerCallBack function. I am going to fix that issue in meteor.js, but it would be better if Meteor will release the next version.

Robotlegs

2011-07-02T00:23:00.000-07:00

After going through some of the MVC framework over the net, Robotlegs seems good. I am going to pick this up in a couple of days and will post my comments. Between I would like to share some of my ready made script over here.