一个窗口包含文本行和标签，在文本行中输入一段文字并且按回车键后，这段文字显现是在标签上

import java.awt.*;
import java.awt.event.*;

public class TowApp extends Frame implements KeyListener {
static TowApp frm = new TowApp();
static TextField tf;
static Label l;

public static void main(String args[]) {

frm.setTitle("习题3");
frm.setSize(250, 150);
frm.setLayout(new FlowLayout());
tf = new TextField(20);//构造新文本字段
l = new Label();//标题
tf.addKeyListener(frm);//监视键盘
frm.add(tf);
frm.add(l);
frm.addWindowListener(new WindowAdapter() {//监控窗口
public void windowClosing(WindowEvent e) {//关闭窗口
System.exit(0);
}
});
frm.setVisible(true);
}

public void keyPressed(java.awt.event.KeyEvent e) {
if (e.getKeyCode() == java.awt.event.KeyEvent.VK_ENTER) {
l.setText(tf.getText());
}
}

@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub

}

@Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub

}

}