samplemenu.java

实例精华

import java.awt.*;
import java.awt.event.*;

public class SampleMenu
    implements ActionListener, ItemListener 
{
  private Frame f;
  private MenuBar mb;
  private Menu m1;
  private Menu m2;
  private Menu m3;
  private MenuItem mi1;
  private MenuItem mi2;
  private MenuItem mi3;
  private MenuItem mi4;
  private CheckboxMenuItem mi5;//这个可以勾选

  public void go() 
  {
    f = new Frame("Menu");
    mb = new MenuBar();
    m1 = new Menu("File");
    m2 = new Menu("Edit");
    m3 = new Menu("Help");
    mb.add(m1);
    mb.add(m2);
    mb.setHelpMenu(m3);//将m3设置为帮助菜单
    f.setMenuBar(mb);//将菜单条添加到frame中使用setMenuBar()方法

    mi1 = new MenuItem("New");
    mi2 = new MenuItem("Save");
    mi3 = new MenuItem("Load");
    mi4 = new MenuItem("Quit");

	
    mi1.addActionListener(this);
    mi2.addActionListener(this);
    mi3.addActionListener(this);
    mi4.addActionListener(this);
    
	m1.add(mi1);
    m1.add(mi2);
    m1.add(mi3);
    m1.addSeparator();
    m1.add(mi4);

    mi5 = new CheckboxMenuItem("Persistent");//创建可勾选的菜单项
    
	mi5.addItemListener(this);
    m1.add(mi5);

    f.setSize(200,200);
    f.setVisible(true);
  }

  public void actionPerformed( ActionEvent ae) 
  {
    System.out.println("Button \"" + 
        ae.getActionCommand() + "\" pressed.");

    if (ae.getActionCommand().equals("Quit")) 
    {
      System.exit(0);
    }
  }
	
	// public void itemStateChanged(ItemEvent ie) 为在用户已选定或取消选定某项时调用
  public void itemStateChanged(ItemEvent ie) 
  {
    String state = "deselected";
	 // ie.getStateChange()返回状态更改的类型（已选定或已取消选定）。ItemEvent.SELECTED此状态更改值指示项被选定
    if (ie.getStateChange() == ItemEvent.SELECTED)
    {
      state = "selected";
    }
    System.out.println(ie.getItem() + " " + state);//getItem()返回受事件影响的项，返回项的名子 
  }

  public static void main (String args[]) 
  {
    SampleMenu sampleMenu = new SampleMenu();
    sampleMenu.go();
  }
}