Where I can teach myself Java online?

many Nptel courses are there which gives you Java tutorials.

just google nptel courses in google.

You will get all the information u need

You have two task here. The first is to learn the Java language. A good start, if you've already got some fundamental notion of programming and exposure to some other programming language, is the Java Tutorial site:

http://download.oracle.com/javase/tutorial/java/

If you're entirely new to programming, consider getting a book. "Head First Java, 2nd Ed." by Sierra and Bates looks pretty good for first-time programmers.

http://search.barnesandnoble.com/Head-First-Java/K...

For experienced programmers who want an in-depth understanding of Java, I recommend "Core Java, Volume I * Fundamentals, 8th Ed." by Horstmann and Cornell. Volume II is great for serious developers, but all the basics are covered in volume I.

http://www.barnesandnoble.com/w/core-java-volume-i...

Then you need to learn the Android APIs. Website tutorials should get you started. I always start with the folks that built the stuff I'm trying to learn. For Android, the starting place is:

http://developer.android.com/

...and click on Guide tab.

Have fun!