Android : Android Push notification Dialog with CountDown TImer

In my app, I show the push notification as a Dialog that has two buttons named 'Yes' and 'No'. I need to show a timer(20secs) running on Dialog Title. If we click 'Yes', It should go to an activity, If 'No' dialog gets canceled before timer ends, After finishing the counting,the Dialog should disappear. Any Idea?? Here is my Alert dialog Method

    public void showAlertDialog(final Context context, String title, String message,
        Boolean status) 
    {
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(context);

    // Setting Dialog Title
    alertDialog.setTitle(title);

    // Setting Dialog Message
    alertDialog.setMessage(message);

    // Setting Icon to Dialog
    //alertDialog.setIcon(R.drawable.fail);

    // Setting Positive "Yes" Button
    alertDialog.setPositiveButton("YES", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) { 
        Toast.makeText(getApplicationContext(), "You clicked on YES", Toast.LENGTH_SHORT).show();

        }
    });

    // Setting Negative "NO" Button
    alertDialog.setNegativeButton("NO", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {      
        Toast.makeText(getApplicationContext(), "You clicked on NO", Toast.LENGTH_SHORT).show();

        dialog.cancel();
        }
    });       

    // Showing Alert Message
    //alertDialog.setIcon(R.drawable.counter);
    alertDialog.show();       
     }
     }