每X秒打印一次“ hello world”

Question

最近我一直在使用带有大量数字的循环来打印Hello World：

int counter = 0;

while(true) {

    //loop for ~5 seconds

    for(int i = 0; i < 2147483647 ; i++) {

        //another loop because it's 2012 and PCs have gotten considerably faster :)

        for(int j = 0; j < 2147483647 ; j++){ ... }

    }

    System.out.println(counter + ". Hello World!");

    counter++;

}

我知道这是一种非常愚蠢的方法，但是我从来没有在Java中使用过任何计时器库。一个如何修改以上内容以每3秒打印一次？

Answer 1

您还可以查看Timer和TimerTask类，这些类可用于计划任务每秒钟运行一次n。您需要一个扩展TimerTask并覆盖该public void run()方法的类，该类将在每次将该类的实例传递给timer.schedule()方法时执行。这是一个示例，Hello World每5秒打印一次：-class SayHello extends TimerTask {&nbsp; &nbsp; public void run() {&nbsp; &nbsp; &nbsp; &nbsp;System.out.println("Hello World!");&nbsp;&nbsp; &nbsp; }}// And From your main() method or any other methodTimer timer = new Timer();timer.schedule(new SayHello(), 0, 5000);

Answer 2

如果要执行定期任务，请使用ScheduledExecutorService。特别是ScheduledExecutorService.scheduleAtFixedRate编码：Runnable helloRunnable = new Runnable() {&nbsp; &nbsp; public void run() {&nbsp; &nbsp; &nbsp; &nbsp; System.out.println("Hello world");&nbsp; &nbsp; }};ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);executor.scheduleAtFixedRate(helloRunnable, 0, 3, TimeUnit.SECONDS);