Question

I need to use a popup window from within a sub thread. Looking around at various snippets of example code, I have arrived at the following:

void completed_dialog()
{
  dialog_action_taken = false;

  runOnUiThread(new Runnable()
  {
    public void run()
    {
      Button but = (Button) findViewById(R.id.pop_can);
      LayoutInflater inflater = (LayoutInflater)
      getSystemService(Context.LAYOUT_INFLATER_SERVICE);
      final PopupWindow pw = new PopupWindow(inflater.inflate(R.layout.endofgame,
           null, false), 300, 300,  true);
      pw.setBackgroundDrawable(new BitmapDrawable());
      OnClickListener cancel_button_click_listener = new OnClickListener() 
      {
        public void onClick(View v) 
        {
          pw.dismiss();
        }
      };
      but.setOnClickListener(cancel_button_click_listener);
      pw.showAtLocation(game_frame_layout, Gravity.CENTER, 0, 0);
   }
  }
}

If the line “but.setOnClickListener(cancel_button_click_listener);” is commented out then I see the dialog and the button perfectly. But if I leave the line in, then the program crashes at the point where the dialog is supposed to appear – i.e. I never see the dialog.
Can I make the code work with just a small modification?

Answer 1

It’s your findViewById() that does not find the button. You need to have it look inside the layout like so

public void run()
{
  LayoutInflater inflater = (LayoutInflater)
  getSystemService(Context.LAYOUT_INFLATER_SERVICE);
  View layout = inflater.inflate(R.layout.endofgame, null, false);
  Button but = (Button) layout.findViewById(R.id.pop_can);
  final PopupWindow pw = new PopupWindow(layout, 300, 300,  true);
  pw.setBackgroundDrawable(new BitmapDrawable());
  OnClickListener cancel_button_click_listener = new OnClickListener() 
  {
    public void onClick(View v) 
    {
      pw.dismiss();
    }
  };
  but.setOnClickListener(cancel_button_click_listener);
  pw.showAtLocation(game_frame_layout, Gravity.CENTER, 0, 0);
}