Android : How to call custom dialog in onActivityResult Android?

I want to show custom dialog in onActivityResult() but it is not displaying on the screen.

Below is my code

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    final Dialog dialog = new Dialog(Activity.this);

    contactDialog.setContentView(R.layout.dialog_layout);

    dialog.show(); 
}