Question

I have implemented Tab in my Application. Now I want to exit application with showing “Are you sure” alert before app closes.

I tried this with
onKeyDown() and onBackPressed() methods but every time it gives Window BadToken Exception.

What could be problem and possible solution for this?

Please have look at stackTrace from LogCat

Thread [<1> main] (Suspended (exception WindowManager$BadTokenException))

ViewRoot.deliverKeyEventToViewHierarchy(KeyEvent, boolean) line: 2523   

ViewRoot.handleFinishedEvent(int, boolean) line: 2443   

ViewRoot.handleMessage(Message) line: 1735  

ViewRoot(Handler).dispatchMessage(Message) line: 99

Looper.loop() line: 123 

ActivityThread.main(String[]) line: 4633    

Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  

Method.invoke(Object, Object...) line: 521  

ZygoteInit$MethodAndArgsCaller.run() line: 858  

ZygoteInit.main(String[]) line: 616

NativeStart.main(String[]) line: not available [native method]  

Answer 1

First you add an instance variable to your Activity that can tell you if its the first time the back button is pressed (a boolean that should be false as default – initialize it in onCreate):

private boolean exiting;

Then override onBackPressed():

@Override
public void onBackPressed() {
  if( !exiting )
    new ExitDialog( this ) ).show();
  else
    super.onBackPressed();
}

The ExitDialog should look as follows:

private class ExitDialog extends AlertDialog implements OnClickListener {
  protected ExitDialog( Context context ) {
    super( context );

    setTitle( "Exit?" );
    setMessage( "Are you sure you want to exit?" );
    setButton( BUTTON_POSITIVE, "Yes", this );
    setButton( BUTTON_NEGATIVE, "No", this );
  }

  public void onClick( DialogInterface dialog, int which ) {
    switch( which ) {
      case BUTTON_POSITIVE:
        exiting = true;
        dialog.dismiss();
        MyActivity.this.onBackPressed();
        break;
      case BUTTON_NEGATIVE:
        exiting = false;
        dialog.dismiss();
        break;
    }
  }
}