jmenuexample.java

自制java的swing组件

package zb.swing;

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

/**
 * JMenuExample: An example of how to use JMenu
 */
public class JMenuExample
    extends JFrame
    implements ActionListener {
  // One will always need a menuBar, when using menus
  JMenuBar menuBar;
  // Individual JMenus are added to the menuBar
  JMenu menu;
  // Then individual menuItems are added to each JMenu
  JMenuItem menuItemNewGame;
  JMenuItem menuItemQuit;

  // This text field will be used to show how to capture an action
  // on a JMenuItem
  JTextField textField = new JTextField("x----------------x");
  FlowLayout layout = new FlowLayout();

  public JMenuExample() {
    // The usual actions on Frames
    this.getContentPane().setLayout(layout);
    this.getContentPane().add(textField);
    // Create the menu bar first.
    menuBar = new JMenuBar();
    setJMenuBar(menuBar);

    // Create the first menu and add it to the menuBar
    menu = new JMenu("File");
    menuBar.add(menu);

    // Now create a group of JMenuItems and add them to the
    // menu created above
    menuItemNewGame = new JMenuItem("New Game");
    menu.add(menuItemNewGame);
    menuItemQuit = new JMenuItem("Quit");
    menu.add(menuItemQuit);

    // The menuItems will require an actionListener
    menuItemNewGame.addActionListener(this);
    menuItemQuit.addActionListener(this);

    // The usual operations on JFrame
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setTitle("JMenu Example");
    this.pack();
    this.setVisible(true);
  }

  /**
   * Capture the actions by the user when selecting a JMenuItem
   */
  public void actionPerformed(ActionEvent e) {
    Object source = e.getSource();
    Class sourceClass = source.getClass();
    // Check if the source of the event is a JMenuItem
    if (sourceClass.getName().equals("javax.swing.JMenuItem")) {
      // Now check which JMenuItem was selected by the user
      JMenuItem item = (JMenuItem) source;
      if (item == menuItemNewGame) {
        textField.setText("New Game!");
      }
      if (item == menuItemQuit) {
        System.exit(0);
      }
    }
  }

  // The main method of the program
  public static void main(String args[]) {
    JFrame frame = new JMenuExample();
  }
}