jcheckboxandjradiomenuitemandreadonly.java

SWING组件与布局管理器例子

/**
 *　菜单的启用与禁用测试
 */
import javax.swing.JMenuBar;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.ButtonGroup;
import javax.swing.SwingConstants;
import javax.swing.ImageIcon;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.event.MenuListener;
import javax.swing.event.MenuEvent;

public class JCheckBoxAndJRadioMenuItemAndReadOnly
{
	public static void main(String[] args)
	{
		JMenuItemFrame  frame = new JMenuItemFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.show();
	}
}

class JMenuItemFrame extends JFrame
{
	private static final int WIDTH = 400;
	private static final int HEIGHT = 300;
	
	private JMenuItem saveItem;
	private JCheckBoxMenuItem readOnlyItem;
	
	public JMenuItemFrame()
	{
        setSize(WIDTH, HEIGHT);//设置框架的大小		
        setTitle("菜单的启用与禁用测试");//设置框架的标题
        
        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);
        
        JMenu fileMenu = new JMenu("文件");
        JMenu editMenu = new JMenu("编辑");
        JMenu helpMenu = new JMenu("帮助");
        
        menuBar.add(fileMenu);
        menuBar.add(editMenu);
        menuBar.add(helpMenu);
        
        saveItem = new JMenuItem("Save");
        JMenuItem exitItem = new JMenuItem("Exit");
        fileMenu.add(saveItem);
        fileMenu.addSeparator();
        fileMenu.add(exitItem);
        
        JMenuItem cutItem = new JMenuItem("Cut", new ImageIcon("cut.gif"));
        JMenuItem pasteItem = new JMenuItem("Paste", new ImageIcon("paste.gif"));
        pasteItem.setHorizontalTextPosition(SwingConstants.LEFT);
        editMenu.add(cutItem);
        editMenu.add(pasteItem);
        editMenu.addSeparator();
        JMenu deleteMenu = new JMenu("Delete");
        editMenu.add(deleteMenu);
        
        readOnlyItem = new JCheckBoxMenuItem("Read Only");
        ButtonGroup group = new ButtonGroup();
        JRadioButtonMenuItem deleteItem = new JRadioButtonMenuItem("Delete");
        JRadioButtonMenuItem insertItem = new JRadioButtonMenuItem("Insert");
        group.add(deleteItem);
        group.add(insertItem);
        insertItem.setSelected(true);//默认的选择项
        
        deleteMenu.add(readOnlyItem);
        deleteMenu.addSeparator();
        deleteMenu.add(deleteItem);
        deleteMenu.add(insertItem);//添加子菜单    	
        
        fileMenu.addMenuListener(new MenuListener()
        {
            public void menuSelected(MenuEvent event)
            {
                saveItem.setEnabled(!readOnlyItem.isSelected());
            }
            
            public void menuDeselected(MenuEvent event){}
            public void menuCanceled(MenuEvent event){}
            });
        
    }
}