//JMenu 继承自JMenuItem，它们都在javax.swing包中，都实现了Accessible, MenuElement 接口import java.awt.Color;import javax.swing.JFrame;import javax.swing.JMenuBar;import javax.swing.JMenu;import javax.swing.JMenuItem;import javax.swing.JPanel;import java.awt.Dimension;import java.awt.MenuShortcut; public class JMenuBarDemo{ public static void main (String[] args) {  //try{javax.swing.UIManager.setLookAndFeel(javax.swing.UIManager.getSystemLookAndFeelClassName());}catch(Exception e){}  JPanel panel = new JPanel ();  panel.setBackground (Color.white);  panel.setPreferredSize (new Dimension (600,400));  //JMenu 有箭头(除了顶层的)，可以添加JMenu和JMenuItem;  //JMenuItem 无箭头，不可添加其他菜单项  JMenu file, edit, search, item, view, format, macro, advance, windows, help;  file = new JMenu ("File");  edit = new JMenu ("Edit");  search = new JMenu ("Search", true);  item = new JMenu ("Item");  view = new JMenu ("View");  format = new JMenu ("Format");  macro = new JMenu ("Macro");  advance = new JMenu ("Advance");  windows = new JMenu ("Windows");  help = new JMenu ("Help");    JMenuItem xin, open, close, save, saveAs;  xin = new JMenuItem ("New", 'n');//热键为'n'  open = new JMenuItem ("Open");  close = new JMenuItem ("Close");  save = new JMenuItem ("Save");  saveAs = new JMenuItem ("Save As");    JMenu del = new JMenu("Del");  del.add ("Del All");  JMenuItem delLine = new JMenuItem ("Del Line"); //这行加下行与上行等价  del.add (delLine);  delLine.setEnabled (false);  edit.add (del);   file.add (xin);  file.add (open);  file.add (close);  file.addSeparator ();//加一条分隔线  file.add (save);  file.add (saveAs);      JMenuBar bar = new JMenuBar ();  bar.add (file);  bar.add (edit);  bar.add (search);  bar.add (item);  bar.add (view);  bar.add (format);  bar.add (macro);  bar.add (advance);  bar.add (windows);  bar.add (help);    JFrame frame = new JFrame ("JMenuBarDemo");  frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);    frame.setContentPane (panel);  frame.setJMenuBar (bar);  frame.pack();  frame.show(); }}

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