Java Swing - 如何创建动态JOptionPane.showMessageDialog

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

public class Main implements ActionListener {
  JFrame myFrame = new JFrame();

  public static void main(String[] a) {
    (new Main()).test();
  }

  private void test() {    
    myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    myFrame.setBounds(50, 50, 250, 150);
    myFrame.setContentPane(new JDesktopPane());
    JMenuBar myMenuBar = new JMenuBar();
    JMenu myMenu = getDialogMenu();
    myMenuBar.add(myMenu);
    myFrame.setJMenuBar(myMenuBar);
    myFrame.setVisible(true);
  }

  private JMenu getDialogMenu() {
    JMenu myMenu = new JMenu("Dialogs");
    JMenuItem myItem = new JMenuItem("Information");
    myItem.addActionListener(this);
    myMenu.add(myItem);
    myItem = new JMenuItem("Warning");
    myItem.addActionListener(this);
    myMenu.add(myItem);
    myItem = new JMenuItem("Error");
    myItem.addActionListener(this);
    myMenu.add(myItem);
    myItem = new JMenuItem("Plain");
    myItem.addActionListener(this);
    myMenu.add(myItem);
    return myMenu;
  }

  public void actionPerformed(ActionEvent e) {
    String menuText = ((JMenuItem) e.getSource()).getText();
    int messageType = JOptionPane.INFORMATION_MESSAGE;
    if (menuText.equals("Information")) {
      messageType = JOptionPane.INFORMATION_MESSAGE;
    } else if (menuText.equals("Warning")) {
      messageType = JOptionPane.WARNING_MESSAGE;
    } else if (menuText.equals("Error")) {
      messageType = JOptionPane.ERROR_MESSAGE;
    } else if (menuText.equals("Plain")) {
      messageType = JOptionPane.PLAIN_MESSAGE;
    }

    JOptionPane.showMessageDialog(myFrame,
        "This is message dialog box of type: " + menuText, menuText
            + " Message", messageType);
  }
}