Android Armory

Android Getting HTML from Webpages

2011-12-06T08:33:00.001-08:00

Before you can access the internet you must enable internet access, add the line below to your AndroidManifest.xml file (I added mine under the minSdkVersion entry)

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

Now you can add this function to get the HTML of a website..

1:  public String getHTML(String urlToRead) {  
2:    URL url;  
3:    HttpURLConnection conn;  
4:    BufferedReader rd;  
5:    String line;  
6:    String result = "";  
7:    try {  
8:      url = new URL(urlToRead);  
9:      conn = (HttpURLConnection) url.openConnection();  
10:      conn.setRequestMethod("GET");  
11:      rd = new BufferedReader(new InputStreamReader(conn.getInputStream()));  
12:      while ((line = rd.readLine()) != null) {  
13:       result += line;  
14:      }  
15:      rd.close();  
16:    } catch (Exception e) {  
17:      Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();  
18:    }  
19:    return result;  
20:   }

And example usage..

String s = getHTML("http://lerietaylor.com/");
Toast.makeText(getApplicationContext(), s, Toast.LENGTH_LONG).show();

Using Android Checkboxes

2011-11-01T11:24:00.000-07:00

In almost any settings window/screen you will probably need to use a check box, to "tick" something on or off. We are going to do some easy check boxes to help make a selection of what kind of fruit we would like to eat. Once the box is selected we will press a "save settings" button to show our selection.

I will assume you already know how to setup a project already. I will be (and have always been) using Eclipse as my IDE. We will have two screens, the first screen will have a button to allow us to move to our settings screen. The next screen is our settings screen, which will let us choose out fruit as mentioned earlier. Below is our first screen in graphical mode in our IDE.

After placing our button on the screen we now make a new activity for our settings screen and a new XML file for our settings screen. If you do not know how to make a new screen I advise you refer to the other tutorials on this website.

The second activity, I named it Settings.java and the XML file is named settings.xml. Here is the code for both files, just in case you need a refresher.

Settings.java
package com.lerie.chkboxdemo;
import android.app.Activity;
import android.os.Bundle;

public class Settings extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.settings);
   }
}

settings.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>

and don't forget to add the new screen to your AndroidManifest.xml file:

      <activity class=".Settings"
                android:name=".Settings"
                android:label="Settings">
      </activity>

As of now, the settings button won't do anything until we set the listener event up. It is quite simple, you can find a tutorial on this website for that as well, it looks a bit like this..

        Button next = (Button) findViewById(R.id.button1);
        next.setOnClickListener(new View.OnClickListener() {
            public void onClick(View view) {
                Intent myIntent = new Intent(view.getContext(), Settings.class);
                startActivityForResult(myIntent, 0);
            }
        });

When the button is clicked it will show the settings screen. Let's design our settings screen now. We will add three checkboxes and a button. If we wanted to group the checkboxes we would simply use RadioButtons instead of checkboxes to make it much easier. With checkboxes we can make multiple selections.

When we make a selection then press the "save settings" button it will pop up a message (with Toast) and show us what we selected then move back to the Main screen we started on. So we need to get the values or at least the state of the checkboxes. It's pretty blatant and straight forward. We will check the "ischecked" method, which is a bool.

First, let's get the checkboxes..

            CheckBox apple = (CheckBox) findViewById(R.id.chkApple);
            CheckBox orange = (CheckBox) findViewById(R.id.chkOrange);
            CheckBox peach = (CheckBox) findViewById(R.id.chkPeach);

After that we can check the methods for the checkboxes..

                if(apple.isChecked())
                {
                    Toast.makeText(Settings.this, "You chose an apple.", Toast.LENGTH_SHORT).show();
                }

                if(orange.isChecked())
                {
                    Toast.makeText(Settings.this, "You chose an orange.", Toast.LENGTH_SHORT).show();
                }

                if(peach.isChecked())
                {
                    Toast.makeText(Settings.this, "You chose a peach.", Toast.LENGTH_SHORT).show();
                }

and then start our other activity..

                Intent myIntent = new Intent(view.getContext(), ChkBoxDemoActivity.class);
                startActivityForResult(myIntent, 0);

Using String Resources

2011-07-15T12:12:00.000-07:00

For quick string references, like a global string, you should try and use the string resource. You can set a string resource by opening the file in your project explorer located at values/strings.xml. In this file is where we will define our strings.

To manually enter a string (assuming your in Eclipse) double click the values/strings.xml file, when the new window opens at the bottom select "strings.xml". In here you can add your own strings in the following format: <string name="{a_name_here}">{you put the string's value in here}</string>

for example, I could store a URL for later use, it would look something like..

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_url_1">http://google.com/</string>
</resource>

We can reference that string in our code like this:

String s = getString(R.string.app_url_1);

Enable Only One Instance of Your Activity

2011-05-07T12:41:00.000-07:00

Open your AndroidManifest and place this code in an activity element that has the MAIN and LAUNCHER intent filters.

android:launchMode="singleInstance"

Publish your Android Application

2011-05-04T18:57:00.000-07:00

The Android Market

The official place to sell Android applications is the Android Market. You can view the market by visiting the website here: https://market.android.com/. Reading the market can help you see which apps are in demand and which area you should develop an app for. All apps need to be digitally signed before they can be sold in the Android Marketplace.

The Distributable File
Android applications are packaged as APK files. You can use the ADT plugin inside Eclipse to digitally sign and compile your applications, that is what we will be focusing on here. Digitally signed applications have a public and private key. A keystore is a place where your (personal) certificates are held. You never want to lose your keystore, make a backup and put it somewhere safe.

Create an APK File
Right click the project and select Android Tools then Export Signed Application Package.

Next, give a name to your project

In the next window you will click the Create new keystore radio button. Select a location on your hardrive by clicking the Browse button and save APK your file, you can name it anything you want. You will need to supply a password by typing it in the two boxes below, like seen below.

In the next part you will need to provide some info, we will only provide the very basics. Provide the password and your name. I am not sure why you must provide at least a 25 year certificate expiration date but... yea, 25 years..

Then finish..

You can sign up and get your Android market account from here, http://market.android.com/publish

Android Multiple Views

2011-04-27T13:45:00.000-07:00

When I first started writing Android apps I never read much documentation as I am a hand on kind of guy. I always do this, I never read the documentation fully and always have to go back over my steps. It’s ok, I just learn slower eh? Well, the problem arose when I wanted to create multiple views. Creating multiple views doesn’t just consist or creating the XML and switching them via an OnClickListener under a button.

You will also need to create another Activity (java file) for the multiple views to work. We are going to make a simple application that will use two buttons and two views. Each view will have a button that switches to the other view. Many applications require more than one view. If you need to setup the environment please refer to my first article, Your First Android App.

I named my project MultiViews and am using Android 2.3. The first thing you can do is go ahead and create the views. The first view has a button that links our second view. The first view is stored in main.xml and our second one is main2.xml. They are identical besides the names of the buttons and the caption on the buttons. Here is a screen shot and the code from both views.

main.xml

1:  <?xml version="1.0" encoding="utf-8"?>  
2:  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3:    android:orientation="vertical"  
4:    android:layout_width="fill_parent"  
5:    android:layout_height="fill_parent"  
6:    >  
7:    <Button android:text="View 2"  
8:          android:id="@+id/button1"  
9:          android:layout_width="fill_parent"  
10:          android:layout_height="wrap_content">  
11:      </Button>  
12:  </LinearLayout>

main2.xml

1:  <?xml version="1.0" encoding="utf-8"?>  
2:  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3:    android:orientation="vertical"  
4:    android:layout_width="fill_parent"  
5:    android:layout_height="fill_parent"  
6:    >  
7:    <Button android:text="View 1"  
8:          android:id="@+id/button2"  
9:          android:layout_width="fill_parent"  
10:          android:layout_height="wrap_content">  
11:      </Button>  
12:  </LinearLayout>

Now, create a new activity MultiViews2.java This will contain essentially the same as the first MultiViews.java file. Here is the First and Second activities files.

MultiViews.java

1:  package com.ler.multiviews;  
2:   import android.app.Activity;  
3:  import android.content.Intent;  
4:  import android.os.Bundle;  
5:  import android.view.View;  
6:  import android.widget.Button;  
7:   public class MultiViews extends Activity {  
8:    /** Called when the activity is first created. */  
9:    @Override  
10:    public void onCreate(Bundle savedInstanceState) {  
11:      super.onCreate(savedInstanceState);  
12:      setContentView(R.layout.main);  
13:    }  
14:  }

MultiViews2.java

1:  package com.ler.multiviews;  
2:   import android.app.Activity;  
3:  import android.content.Intent;  
4:  import android.os.Bundle;  
5:  import android.view.View;  
6:  import android.widget.Button;  
7:   public class MultiViews2 extends Activity {  
8:    /** Called when the activity is first created. */  
9:    @Override  
10:    public void onCreate(Bundle savedInstanceState) {  
11:      super.onCreate(savedInstanceState);  
12:      setContentView(R.layout.main2);  
13:    }  
14:  }

We now have to add the Listeners to the Activity files, to let us click the buttons. Here is the first one:

1:      Button next = (Button) findViewById(R.id.button1);  
2:      next.setOnClickListener(new View.OnClickListener() {  
3:        public void onClick(View view) {  
4:          Intent myIntent = new Intent(view.getContext(), MultiViews2.class);  
5:          startActivityForResult(myIntent, 0);  
6:        }  
7:      });

and the second:

1:      Button next = (Button) findViewById(R.id.button1);  
2:      next.setOnClickListener(new View.OnClickListener() {  
3:        public void onClick(View view) {  
4:          Intent myIntent = new Intent(view.getContext(), MultiViews.class);  
5:          startActivityForResult(myIntent, 0);  
6:        }  
7:      });

Now, you will need to open your AndroidManifest.xml file and add the Activity to it, the second class we wrote.

1:  <activity android:name=".MultiViews2"></activity>

Creating Your First Android App

2011-04-27T13:43:00.000-07:00

Today I am going to walk you through installing and setting up the Android SDK so you can create android applications. Android runs on Java, so if you don’t know Java, please step away now. If you want to try it anyway, keep following along. We first need to install JDK, the Java Development Kit. We will be installing JDK 5 which is the latest version as of writing this.

We will be using Windows to install these on, I will be using x86, you can probably follow along on the other OS’s Java supports, but if your semi new to this, you might want to open Windows in a VM to follow along. Hopefully by now your installing or at least downloading the JDK. I downloaded jdk-6u24-windows-i586.exe. I even created a small YouTube video for the install, which is pretty much point and click next..

We haven’t really discussed what kind of app we will be making. We will be writing a simple app of course, nothing too fancy. We will not be integrating controls at this time such as Buttons or Labels, that will follow in the next tutorial where we will be creating a simple calculator. For now, we need to continue with our setup and install our IDE, we will be using Eclipse. The Eclipse IDE is something I have been using for quite some time, since I went through the core. No, not the corps., the core. The core is something familiar to programmers, it is the basis/structure from which most coders who have gone to school learn the basics and fundamentals for programming.

Once Eclipse installs it has options to download and install the Android SDK. I will be downloading and installing helios SR2. There is an option to download it via torrent, which id the option I am going to use. Once it is done downloading just extract the eclipse folder to a place of your choosing and start the IDE.

On the left is the default package for the Eclipse IDE we downlaoded, click the eclipse.exe to get it going. It will ask you to select a workspace, just hit ok or whatever it asks, unless you want to specify a different location. Once it loads go into the Help menu at the top and select Install New Software. A new windows will pop up and enter the URL: https://dl-ssl.googl...android/eclipse into it and press enter. Select them all and click Next at the bottom to start installing. It may take a while depending on your PC’s speed and internet connection, just be patient. Accept the License Agreements and click Finish. You will have to restart Eclipse.

Now, go to Window then select Preferences and select Android from the left menu and then select the Android version, we will be using 1.5 for this project, press the Apply button.

Now open the AVD manager.

Select start to start the Android emulator. It may take a while to load, it looks something like below.

The images presented in this tutorial are for the 1.5 AVD, however here is a video that shows how to load the AVD, but it is using 2.3, it still shows you how to load the AVD from within Eclipse.

For now, we can just load a new Android project and do a simple Hello World. Select File then New Project and select the Android project.

Now setup the projects preferences.

Instead of typing 1.5 for the Minimum SDK version type 3 instead. My bad, when compiling the project you can get an error like this: [2011-03-16 12:00:05 - HelloWorld] Manifest attribute ‘minSdkVersion’ is set to ’1.5′. Integer is expected. Then you will know exactly what I did wrong previously, typing 1.5 instead of 3. You should be able to open the AndroidManifest.xml file and edit the 1.5 and change it to 3.

Now, we should be good to go and place a simple Hello World in the source.

package com.lerie.helloworld;
 import android.app.Activity;
import android.os.Bundle;
 public class HelloWorld extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
 
        System.out.println("Hello World!");
    }
}

You can now open the AVD manager, launch the Android and run the demo. (the green play button in the toolbar). Enjoy.

Creating Mockups with DroidDraw

2011-04-27T13:37:00.001-07:00

DroidDraw is a free tool in java meant to help ease the life of a droid developer. I love the interface in Eclipse but nothing beats this when your on the go. It is lacking controls but works well for beginners, probably someone like you. it's not a bad tool at all, enjoy.

The first thing you should do is decide on a layout. I will select the Table Layout. Just drag the TableLayout control onto the droid interface to the left.

next, position the TableLayout however you want, as wide or high as you want. Our other controls will be inside here.

next, drag a TableRow onto the TableLayout and make sure to select the TableLayout when you drag it over.

now we can add some controls. Add a button by dragging it onto the TableRow you put up just a minute ago.

When your done, you can click the generate button at the top then copy that code into your view's XML file.

I have attached the project files to this post.

Clicking a Button

2011-04-27T13:34:00.000-07:00

This isn't a copy and paste tutorial that your accustomed to seeing in this section. I thought I would step up and show one of my skills since this section seems lacking. I will probably write more Android tutorials including how to create the APK file to actually put them on an Android. In this tutorial we are going to click a button. Simple I know, but most can't even get past this. If you don't know anything about Java or event listeners then you might want to go read up on it before you continue. Also in this tutorial you will use Toast to show that you clicked the button since it's the easiest way.

Android's toast is a little popup message that fades in and out as we call it. We can control it's fade time and some other features as indicated on the developer page but that isn't what we are focusing on here. We are focused on actually getting one to display after a button has been clicked. Toast is a view.

The first thing we need to do is add a button to our layout. Select the XML file from the folder tree on the left (in the Package Explorer) and double click (open) the XML file.

The file should load in the pane on the right hand side. If this is a new project delete the default text that comes with it. If you delete the text here be sure to delete it from the app_strings also. Not deleting it from app_strings won't damage the application but it's nice to keep it clean. Click and drag the button onto the form.

Now change the width so it's not so ugly.

Now that our button's name is button1. We are going to add another library to reference at the top witht he rest that will give us access to use the OnClickListener event handler.

import android.view.View;
import android.widget.Button;
import android.widget.Toast;

create a button and locate our button in the interface and apply it tot he newly created button.

final Button btn = (Button) findViewById(R.id.button1);

then add an eventlistener to it

btn.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        Toast.makeText(getApplicationContext(), "Button clicked!", 100).show();
    }
});

It should be ready to go, here is what the end result s hould look like. I have also attached the project files for it tot his post.