参考答案

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Lx9_4 implements ActionListener {
JFrame f;
JPanel p;
JTextField text1;
JLabel j;
JButton b1,b2;
public Lx9_4(){
f=new JFrame("Lx9_4按钮转换文字");
p=new JPanel();
j=new JLabel("Lx9_4习题演示");
p.setLayout(new GridLayout(1,2));
text1=new JTextField(30);
b1=new JButton("文本一");
b2=new JButton("文本二");
b1.setActionCommand("t1");
b2.setActionCommand("t2");
b1.addActionListener(this);
b2.addActionListener(this);
p.add(b1);
p.add(b2);
f.getContentPane().add(text1,BorderLayout.NORTH);
f.getContentPane().add(p,BorderLayout.CENTER);
f.getContentPane().add(j,BorderLayout.SOUTH);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);
}
public void actionPerformed(ActionEvent Eve){
if(Eve.getActionCommand().equals("t1")){
text1.setText("Hello Java!");
}
else if(Eve.getActionCommand().equals("t2")){
text1.setText("你好 Java！");
}
}
public static void main(String a[]){
Lx9_4 c1=new Lx9_4();
}
}