java定时任务

package com.yy;import java.io.File;import java.util.ArrayList;import java.util.Date;import java.util.List;import java.util.concurrent.Executors;import java.util.concurrent.ScheduledExecutorService;import java.util.concurrent.TimeUnit;public class TimerTask {    public static void main(String[] args) {          Runnable runnable = new Runnable() {              public void run() {                  // task to run goes here                  System.out.println("开始执行定时任务："+Tool.stringOfDateTime(new Date()));                  }        };          ScheduledExecutorService service = Executors                  .newSingleThreadScheduledExecutor();          // 第二个参数为首次执行的延时时间，第三个参数为定时执行的间隔时间，第四个参数为时间单位          service.scheduleAtFixedRate(runnable, 8, 24, TimeUnit.HOURS);      }  }