在ScheduledExecutorService中重新初始化修复延迟

问题描述

根据我的要求，我必须在一段时间后执行一些特定的代码.为此，我选择了ScheduledExecutorService.scheduleWithFixedDelay(runnable, 0, 5, TimeUnit.SECONDS)，对我来说很好.但是根据我的另一个要求，fixedDelay中提到的时间应该可以在运行时配置.意味着，当前的总延迟为5秒，但是如果用户愿意，可以将其更改为60秒，并且在运行时fixedDelay将在60秒后运行.任何帮助都将是可观的.

As per my requirement, I have to execute some particular code after certain period of time. To do the same I have chose ScheduledExecutorService.scheduleWithFixedDelay(runnable, 0, 5, TimeUnit.SECONDS) and it's working fine for me. But according to my another requirement, the time mentioned in fixedDelay should be configurable at runtime. Means, currently total Delay is 5 seconds but latter if user want then can change the time into 60 seconds and in runtime fixedDelay will run after 60 seconds. Any help would be appreciable.

请查看代码:

static int i = 0;
    static ScheduledExecutorService executor;
    static Runnable runnable;
    static ScheduledFuture<?> future;

    public static void main(String args[]) {
        executor = Executors
                .newScheduledThreadPool(1);
        runnable = new Runnable() {
            @Override
            public void run() {
                System.out.println("Inside runnable" + i++);
                changeDelay();
            }
        };
        future =
                executor.scheduleWithFixedDelay(runnable, 0, 5, TimeUnit.SECONDS);

    }

    public static void changeDelay() {
        future.cancel(false);
        future = executor.scheduleWithFixedDelay(runnable, 0, 10, TimeUnit.SECONDS);
    }

在这里，我使用了changeDelay方法来更改延迟时间.但这不起作用.

Here I have used changeDelay method to change the delay time. But it's not working.

推荐答案

您需要保留返回的ScheduledFuture<?>对象的引用:

You need to keep the reference of the returned ScheduledFuture<?> object:

ScheduledFuture<?> handle =
       scheduler.scheduleWithFixedDelay(runnable, 0, 5, TimeUnit.SECONDS);

使用此参考，您可以取消当前任务并创建另一个具有新延迟的任务:

With this reference you cancel the current task and create another one with the new delay:

handle.cancel(false);
handle = scheduler.scheduleWithFixedDelay(runnable, 0, 60, TimeUnit.SECONDS);

这里是一个例子:

public class Test5 {
    static int i = 0;
    static ScheduledExecutorService executor;
    static Runnable runnable;
    static ScheduledFuture<?> future;

    public static void main(String args[]) throws InterruptedException{
        executor = Executors.newScheduledThreadPool(1);
        runnable = new Runnable() {
            @Override
            public void run() {
                System.out.println("Inside runnable" + i++);
            }
        };
        future = executor.scheduleWithFixedDelay(runnable, 0, 5, TimeUnit.SECONDS);

        Thread.sleep(20000l);

        changeDelay();
    }

    public static void changeDelay() {
        boolean res = future.cancel(false);

        System.out.println("Previous task canceled: " + res);

        future = executor.scheduleWithFixedDelay(runnable, 0, 20, TimeUnit.SECONDS);
    }
}

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