经典笔试题：通过JDK自带工具实现一个间隔并发执行的定时任务

通过JDK自带工具实现一个间隔并发执行的定时任务，代码如下：

public class Test{

    public static void main(String[] args) {
        ScheduledThreadPoolExecutor scheduledThreadPoolExecutor = new ScheduledThreadPoolExecutor(1);
        scheduledThreadPoolExecutor.scheduleWithFixedDelay(new Runnable() {
            @Override
            public void run() {
                System.out.print(LocalDateTime.now() + " ");
                System.out.println(Thread.currentThread().getName() + "= test scheduleWithFixedDelay......");
            }
        }, 3, 2, TimeUnit.SECONDS);// 3秒后开始执行任务，每隔2秒执行任务
    }

}

执行结果如下：

2020-05-24T20:17:32.022 pool-1-thread-1= test scheduleWithFixedDelay......
2020-05-24T20:17:34.023 pool-1-thread-1= test scheduleWithFixedDelay......
2020-05-24T20:17:36.025 pool-1-thread-1= test scheduleWithFixedDelay......
2020-05-24T20:17:38.026 pool-1-thread-1= test scheduleWithFixedDelay......
2020-05-24T20:17:40.029 pool-1-thread-1= test scheduleWithFixedDelay......
2020-05-24T20:17:42.030 pool-1-thread-1= test scheduleWithFixedDelay......
2020-05-24T20:17:44.031 pool-1-thread-1= test scheduleWithFixedDelay......