menueventdemo.java

《java事件处理指南》一书的代码,好东西

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class MenuEventDemo extends JFrame
{
   private JMenuBar menuBar;
   private JMenu fontMenu, fileMenu;
   private JTextField jtf;

   public MenuEventDemo() 
   {
/*  Two JMenu objects are created and placed on a Frame. The menus  */
/*  register a MenuEventListener.                                   */

      fileMenu = new JMenu("File");
      fileMenu.setFont(new Font("Serif", Font.BOLD, 12));
      fileMenu.add(new JMenuItem("Open"));
      fileMenu.add(new JMenuItem("Quit"));
      fileMenu.addMenuListener(new MenuHandler());

      fontMenu = new JMenu("Font Size");
      fontMenu.setFont(new Font("Serif", Font.BOLD, 12));
      fontMenu.add(new JMenuItem("10"));
      fontMenu.add(new JMenuItem("12"));
      fontMenu.add(new JMenuItem("14"));
      fontMenu.addMenuListener(new MenuHandler());

      menuBar = new JMenuBar();
      menuBar.add(fileMenu);
      menuBar.add(fontMenu);

      jtf = new JTextField(15);
      jtf.setEditable(false);

      getContentPane().add(menuBar, BorderLayout.NORTH);
      getContentPane().add(jtf, BorderLayout.SOUTH);

      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 300, 200);
      setVisible(true);
   }

/*  The MenuListener is implemented as an inner class.  If one of   */
/*  the menus is selected or deselected, a MenuEvent is generated   */
/*  and sent to either the menuDeselected() or menuSelected()       */
/*  methods.  These methods determine the event source and print    */
/*  a message about the nature of the event in a JTextField.        */
/*  The menuCanceled() method is not used in this example, so it    */
/*  is implemented as a stub method.                                */

   class MenuHandler implements MenuListener
   {
      public void menuDeselected(MenuEvent event)
      {
         JMenu menu = (JMenu)event.getSource();
         jtf.setText(menu.getActionCommand()+" menu deselected");
      }

      public void menuSelected(MenuEvent event)
      {
         JMenu menu = (JMenu)event.getSource();
         jtf.setText(menu.getActionCommand()+" menu selected");
      }

      public void menuCanceled(MenuEvent event) {}
   }

   public static void main(String args[]) 
   {
      MenuEventDemo demo = new MenuEventDemo();
   }
}