Android Programming - Override Back Button

Overriding back button is much more simple than options menu before.

@Override
    public void onBackPressed() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setMessage("You've pressed the back button\nThanks.")
               .setTitle("Back Pressed")
               .setCancelable(true);
        builder.create().show();
    }

That's it. You're done. It create an AlertDialog when back button pressed.