要用JMenuItem,我改的:import java.awt.event.*;
import javax.swing.*;public class MenuDemo extends JFrame{
JMenuBar mb = new JMenuBar();
JMenu fileMenu = new JMenu("文件");
JLabel l1 = new JLabel("选择项目");
public MenuDemo()
{
JMenuItem project1 = new JMenuItem( "项目1" );
project1.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent e ) {
l1.setText( "项目1" );
}
}); JMenuItem project2 = new JMenuItem( "项目2" );
project2.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent e ) {
l1.setText( "项目2" );
}
});
JMenuItem exit = new JMenuItem( "退出" );
exit.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.exit( 0 );
}
}); fileMenu.add( project1 );
fileMenu.add( project2 );
fileMenu.add( exit );
mb.add(fileMenu);
mb.add(l1);
setJMenuBar(mb);
} public static void main(String args[])
{
MenuDemo md = new MenuDemo();
md.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
md.setSize(300,300);
md.show();
}
}
import javax.swing.*;public class MenuDemo extends JFrame{
JMenuBar mb = new JMenuBar();
JMenu fileMenu = new JMenu("文件");
JLabel l1 = new JLabel("选择项目");
public MenuDemo()
{
JMenuItem project1 = new JMenuItem( "项目1" );
project1.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent e ) {
l1.setText( "项目1" );
}
}); JMenuItem project2 = new JMenuItem( "项目2" );
project2.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent e ) {
l1.setText( "项目2" );
}
});
JMenuItem exit = new JMenuItem( "退出" );
exit.addActionListener( new ActionListener() {
public void actionPerformed( ActionEvent e ) {
System.exit( 0 );
}
}); fileMenu.add( project1 );
fileMenu.add( project2 );
fileMenu.add( exit );
mb.add(fileMenu);
mb.add(l1);
setJMenuBar(mb);
} public static void main(String args[])
{
MenuDemo md = new MenuDemo();
md.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
md.setSize(300,300);
md.show();
}
}
JMenuItem menuP1 =new JMenuItem("项目1");
JMenuItem menuP2 =new JMenuItem("项目2");
JMenuItem menuExit =new JMenuItem("退出");menuP1.addMouseListener(new MouseListener() {...});
menuP2.addMouseListener(new MouseListener() {...});
menuExit.addMouseListener(new MouseListener() {...});
fileMenu.add(menuP1);
fileMenu.add(menuP2);
fileMenu.add(menuExit);