这段java代码为什么要这样才能运行
import javax.swing.*;
import java.awt.*;
import java.io.*;
import java.awt.event.*;
public class Editor extends JFrame implements ActionListener {
JPanel Panel = new JPanel();
JTextArea editor = new JTextArea(30, 60);
JMenuItem kaiti = new JMenuItem("楷体");
JMenuItem lishu = new JMenuItem("隶书");
JMenuItem yahei = new JMenuItem("微软雅黑");
Editor() {
super("文本编辑器 ");
setBounds(250, 100, 700, 450);
setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
int option = JOptionPane.showConfirmDialog(Editor.this, "确定要退出吗？ ", "Warning ",
JOptionPane.YES_NO_OPTION);
if (option == JOptionPane.YES_OPTION)
if (e.getWindow() == Editor.this) {
System.exit(0);
} else {
return;
}
}
});
add(new JScrollPane(editor));// );
editor.setFont(new Font("宋体", Font.PLAIN, 20));
JMenuBar wenben = new JMenuBar();
this.setJMenuBar(wenben);
wenben.setOpaque(true);
JMenu custom = new JMenu("自定义");
JMenu OptionM = new JMenu("字体");
custom.add(OptionM);
OptionM.add(kaiti);
OptionM.add(lishu);
OptionM.add(yahei);
wenben.add(custom);
kaiti.addActionListener(this);
lishu.addActionListener(this);
yahei.addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
String actionCommand = e.getActionCommand();
if (e.getSource() instanceof JMenu) {
if (e.getSource() == kaiti) {
editor.setFont(new Font("楷体", Font.PLAIN, editor.getFont().getSize()));
} else if (e.getSource() == lishu) {
editor.setFont(new Font("隶书", Font.PLAIN, editor.getFont().getSize()));
} else if (e.getSource() == yahei) {
editor.setFont(new Font("微软雅黑", Font.PLAIN, editor.getFont().getSize()));
}
}
}
}
还是说这写不行。求指教,就是actionPerformed不执行。
//我发现在if (e.getSource() instanceof JMenu)的后面加上分号就可以运行了，这是什么原因呢
