import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Date;

public class TimePrinter implements ActionListener {
    public void actionPerformed(ActionEvent event){
        System.out.println("現在的時間是"+new Date());
        Toolkit.getDefaultToolkit().beep(); 
 
//發出一聲鈴響
    }
}

import javax.swing.Timer;
import java.awt.event.ActionListener;

public class Main {
    public static void main(String[] args){
        ActionListener listener = new TimePrinter();
        Timer t = new Timer(10000,listener);//10秒跑一次
        t.start();//啟動定時器
    }
}

java定時器Timer