Double tap to exit xamarin android

MainActivity.cs

private bool doubleBackToExitPressedOnce = false;
public override void OnBackPressed()
        {
            if (doubleBackToExitPressedOnce)
            {
                base.OnBackPressed();
                Java.Lang.JavaSystem.Exit(0);
                return;
            }


            this.doubleBackToExitPressedOnce = true;
            Toast.MakeText(this, "Double tap to exit", ToastLength.Short).Show();

            new Handler().PostDelayed(() =>
            {
                doubleBackToExitPressedOnce = false;
            }, 2000);
        }