Android Studio : Afficher une boîte de dialogue

public void showOkDialog(String title, String message) {
    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
    alertDialogBuilder.setTitle(title);
    alertDialogBuilder
            .setMessage(message)
            .setCancelable(false)
            .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
                }
            });

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