Java中的菜单--JPopupMenu

一个小程序实现菜单：		
		
		import java.awt.*;
		import java.awt.event.ActionEvent;
		import java.awt.event.ActionListener;
		import java.awt.event.KeyEvent;
		import java.awt.event.MouseEvent;
		import java.awt.event.MouseListener;
		
		import javax.swing.JFrame;
		import javax.swing.*;
		
		class mouseAdapt implements MouseListener
		{
			public void mouseClicked(MouseEvent e){}
			public void mousePressed(MouseEvent e){}
			public void mouseReleased(MouseEvent e){}
			public void mouseEntered(MouseEvent e){}
			public void mouseExited(MouseEvent e){}
			
		}
		
		
		public class Menue extends mouseAdapt implements ActionListener{
			JFrame frame = new JFrame(\"popupMenu\");
			JPopupMenu popup = new JPopupMenu();
			JTextField tf = new JTextField();
			JLabel label = new JLabel(\"Try to click left and button\");
			
			public static void main(String [] ary)
			{
				Menue menue = new Menue();
				menue.go();
			}
			
			void go()
			{
				JMenuItem menuitem = new JMenuItem(\"NEW\", KeyEvent.VK_N);
				menuitem.addActionListener(this);
				popup.add(menuitem);
				
			    menuitem = new JMenuItem(\"LOAD\", KeyEvent.VK_L);
				menuitem.addActionListener(this);
				popup.add(menuitem);
				
				menuitem = new JMenuItem(\"SAVE\", KeyEvent.VK_S);
				menuitem.addActionListener(this);
				popup.add(menuitem);
				
				popup.addSeparator();
				
				 menuitem = new JMenuItem(\"COPY\", KeyEvent.VK_C);
				menuitem.addActionListener(this);
				popup.add(menuitem);
				
			    menuitem = new JMenuItem(\"CUT\", KeyEvent.VK_T);
				menuitem.addActionListener(this);
				popup.add(menuitem);
				
				menuitem = new JMenuItem(\"PASTE\", KeyEvent.VK_T);
				menuitem.addActionListener(this);
				popup.add(menuitem);
				
				label.addMouseListener(this);
				
				tf.setEditable(false);
				
				Container cp = frame.getContentPane();
				cp.add(label, BorderLayout.CENTER);
				cp.add(tf, BorderLayout.SOUTH);
				
				frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
				frame.setVisible(true);
				frame.setSize(300, 200);
				
			}
			
			public void mousePressed(MouseEvent e)
			{
				maybeShowPopup(e);
			}
			
			public void mouseReleased(MouseEvent e)
			{
				maybeShowPopup(e);
			}
			
			private void maybeShowPopup(MouseEvent e)
			{
				if(e.isPopupTrigger())
				{
					popup.show(e.getComponent(), e.getX(), e.getX());
				}
			}
			
			public void actionPerformed (ActionEvent e)
			{
				tf.setText(e.getActionCommand());
				
				if(e.getActionCommand() == \"EXIT\")
				{
					System.exit(0);
				}
			}
		
		
		}