Is there a way to add a badge to an application icon in Android?

Unfortunately, Android does not allow changing of the application icon because it's sealed in the APK once the program is compiled. There is no way to programmatically change it to a 'drawable'.

You may achieve your goal by using a widget instead of an icon. Widgets are highly customisable and can do what you want.

There's a short discussion about the difference between iPhone icon notification and using widgets here:

http://www.cnet.com/8301-19736_1-10278814-251.html

As you'll notice, there is virtually no difference between using a widget or an icon, since they can be the same size and look the same.

This can also be done for Sony's Xperia Home. I've blogged about it here, but the important parts are below. Sony devices use a class named BadgeReciever.

1. Declare the com.sonyericsson.home.permission.BROADCAST_BADGE permission in your manifest file:

2. Broadcast an Intent to the BadgeReceiver:

   Intent intent = new Intent();
   
   intent.setAction("com.sonyericsson.home.action.UPDATE_BADGE");
   intent.putExtra("com.sonyericsson.home.intent.extra.badge.ACTIVITY_NAME", "com.yourdomain.yourapp.MainActivity");
   intent.putExtra("com.sonyericsson.home.intent.extra.badge.SHOW_MESSAGE", true);
   intent.putExtra("com.sonyericsson.home.intent.extra.badge.MESSAGE", "99");
   intent.putExtra("com.sonyericsson.home.intent.extra.badge.PACKAGE_NAME", "com.yourdomain.yourapp");
   
   sendBroadcast(intent);
   

3. Done. Once this Intent is broadcast the launcher should show a badge on your application icon.

4. To remove the badge again, simply send a new broadcast, this time with SHOW_MESSAGE set to false:

   intent.putExtra("com.sonyericsson.home.intent.extra.badge.SHOW_MESSAGE", false);
   

I've excluded details on how I found this to keep the answer short, but it's all available in the blog. Might be an interesting read for someone.

I've also posted a seperate SO question about this here and will add the full answer there once I'm allowed to (need 10 reputation to answer my own question within 8 hours).

ShortcutBadger library makes it possible and works with LG, Sony, Samsung, HTC and other custom Launchers.

It even has a way to display Badge Count in Pure Android devices desktop.

Updating the Badge Count in the application icon is as easy as calling:

int badgeCount = 1;
ShortcutBadger.setBadge(getApplicationContext(), badgeCount);

It includes a demo application that allows you to test its behaviour.

OR

you can also try activity-alias to do so, but in this you need to create different icons with badge values ,it will work great in case- you need to switch between 2 different App icons (need to create different activity-alias for displaying different icon i.e more icons = more activity-alias).