public void delete() { boolean status = Controller.getInstance().deleteStudent(_id); QMessageBox t = new QMessageBox(); t.setWindowIcon(new QIcon(new QPixmap("classpath:admin_resource/eot_icon.png"))); if (status) { holder.hide(); holder.close(); t.setText("The deletion was a success"); t.setWindowTitle("Success"); t.exec(); // Controller.getInstance().work(); } else { t.setText("The deletion failed"); t.setWindowTitle("Failed"); t.exec(); // Controller.getInstance().work(); } }