java核心技术得代码自己照着输一遍有错误 错误提示在 ActionListener listener=new TimePrinter();

Question

package diliuzhang;import java.awt.*;import java.awt.event.*;import java.util.*;import javax.swing.*;import javax.swing.Timer;public class TimerTest { public static void main(String[] args) { ActionListener listener=new TimePrinter(); Timer t=new Timer(10000,listener); t.start(); JOptionPane.showMessageDialog(null, "Quit program?"); System.exit(0); } class TimePrinter implements ActionListener{ public void actionPerformed(ActionEvent event) { System.out.println("At the tone,tjis time is"+new Date()); Toolkit.getDefaultToolkit().beep(); } }}