android show alert dialog when exit app

// close android app programmatically

@Override
public void onBackPressed() {
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
    alertDialogBuilder.setTitle("Exit Application?");
    
    alertDialogBuilder
            .setMessage("Click yes to exit!")
            .setCancelable(false)
            .setPositiveButton("Yes",
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int id) {
                            moveTaskToBack(true);
                            android.os.Process.killProcess(android.os.Process.myPid());
                            System.exit(1);
                        }
                    })

            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {

                    dialog.cancel();
                }
            });

    AlertDialog alertDialog = alertDialogBuilder.create();
    alertDialog.show();
}