Disable back button in android

Override the onBackPressed method and do nothing if you meant to handle the back button on the device.

@Override
public void onBackPressed() {
   if (shouldAllowBack()) {
       super.onBackPressed();
   } else {
       doSomething();
   }
}

If looking for a higher api level 2.0 and above this will work great

@Override
public void onBackPressed() {
    // Do Here what ever you want do on back press;
}

If looking for android api level upto 1.6.

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
     if (keyCode == KeyEvent.KEYCODE_BACK) {
     //preventing default implementation previous to android.os.Build.VERSION_CODES.ECLAIR
     return true;
     }
     return super.onKeyDown(keyCode, event);    
}

Write above code in your Activity to prevent back button pressed

You can do this simple way Don't call super.onBackPressed()

Note:- Don't do this unless and until you have strong reason to do it.

@Override
public void onBackPressed() {
// super.onBackPressed();
// Not calling **super**, disables back button in current screen.
}