Question

编写一个java applet程序，有两个文本框组件，

当在一个文本框输入数字字符并按Enter键后，另一个文本框显示该数字的平方

Answer 1

import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.applet.*;

public class AppletTest extends Applet
{
Label lb1;
Label lb2;
TextField tf1,tf2;

public void init()
{
lb1 = new Label("输入");
lb2 = new Label("输出");

tf1 = new TextField(5);
tf2 = new TextField(5);

tf1.requestFocus();
tf1.addKeyListener(new KeyListener() {
public void keyReleased(KeyEvent e) {}

public void keyTyped(KeyEvent e) {}

public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER)
{
int num = Integer.parseInt(tf1.getText());
tf2.setText(String.valueOf(num*num));
}
else if (e.getKeyCode() == KeyEvent.VK_ESCAPE) {
System.exit(0);
}

}
});
setLayout(new FlowLayout());

add(lb1);
add(tf1);

add(lb2);
add(tf2);

setSize(300,100);

}

}

Answer 2

自己先学会写写代码，这个一点不难！ 调试不出来可以问问！

Answer 3

import java.awt.event.KeyListener;
import java.applet.*;
public class AppletTest extends Applet
{
Label lb1;
Label lb2;
TextField tf1,tf2;
public void init()
{
lb1 = new Label("输入");
lb2 = new Label(