Error Message als Fenster ausgeben

import java.awt.event.KeyEvent;

import java.awt.event.KeyAdapter;

import javax.swing.JOptionPane;

import javax.swing.JTextField;

import javax.swing.JPanel;

import javax.swing.JFrame;

public class Test extends JFrame {

    public Test() {

        JPanel panel = new JPanel();

        JTextField field = new JTextField("Hier was Eingeben");

        field.addKeyListener(new KeyAdapter() {

            public void keyPressed(KeyEvent evt) {

                int keyCode = evt.getKeyCode();

                if (keyCode == KeyEvent.VK_ENTER || keyCode == KeyEvent.VK_TAB) {

                    if (!field.getText().equals("Richtige Eingabe")) {

                        JOptionPane.showMessageDialog(null, "Da wurde jetzt aber was falsches eingegeben!", "Falsche Eingabe", JOptionPane.ERROR_MESSAGE);

                    }

                }

            }

        });

        panel.add(field);

        getContentPane().add(panel, java.awt.BorderLayout.CENTER);

        pack();

    }

    public static void main(String args[]) {

        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {

                new Test().setVisible(true);

            }

        });

    }

}