How to use

onKeyDown

method

in

android.app.ActivityGroup

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
  Activity target = getCurrentActivity();
  if (target != null) {
    return target.onKeyDown(keyCode, event);
  } else {
    return super.onKeyDown(keyCode, event);
  }
}

  @Override
  public boolean onKeyDown(int keyCode, KeyEvent event) {
    if(keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_DOWN){
      MessageDialog dialog = new MessageDialog(MainActivity.this,
          getString(R.string.common_title_tips),
          getString(R.string.common_confirm),
          getString(R.string.common_cancel),
          getString(R.string.common_exit));
      dialog.setBtn1ClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
          LruCacheManager.getInstance().evictAll();
          ActivityPageManager.getInstance().exit(MainActivity.this);
        }
      });
      dialog.show();
      return true;
    }
    return super.onKeyDown(keyCode, event);
  }
}