back key

 general on back :
@Override
    public boolean onKeyDown(int keyCode, KeyEvent event)  {
        if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) {
            // do something on back.
       
      return true;
        }
        return super.onKeyDown(keyCode, event);
    }

Not to call onDestroy on onBackPressed

 URL:http://stackoverflow.com/questions/6173980/androi-not-to-call-ondestroy-on-onbackpressed

public boolean onKeyDown(int keyCode, KeyEvent event)  {

     if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0)
     {

        this.moveTaskToBack(true);
           return true;
      }

    return super.onKeyDown(keyCode, event);
}