如何为Executors.newScheduledThreadPool（5）设置RemoveOnCancelPolicy

Question

我有这个：

ScheduledExecutorService scheduledThreadPool = Executors
        .newScheduledThreadPool(5);

然后，我开始执行如下任务：

scheduledThreadPool.scheduleAtFixedRate(runnable, 0, seconds, TimeUnit.SECONDS);

我这样保存对未来的引用：

ScheduledFuture<?> scheduledFuture = scheduledThreadPool.scheduleAtFixedRate(runnable, 0, seconds, TimeUnit.SECONDS);

我希望能够取消 和删除 未来

scheduledFuture.cancel(true);

但是，此SO答案指出，取消操作不会将其删除，而添加新任务将以许多无法使用GC的任务结束。

http://codingdict.com/questions/155838

他们提到了有关的内容setRemoveOnCancelPolicy，但是这种scheduledThreadPool方法没有。我该怎么办？

Answer 1

此方法在ScheduledThreadPoolExecutor中声明。

/**
 * Sets the policy on whether cancelled tasks should be immediately
 * removed from the work queue at time of cancellation.  This value is
 * by default {@code false}.
 *
 * @param value if {@code true}, remove on cancellation, else don't
 * @see #getRemoveOnCancelPolicy
 * @since 1.7
 */
public void setRemoveOnCancelPolicy(boolean value) {
    removeOnCancel = value;
}

Executors类通过newScheduledThreadPool和类似方法返回此执行程序。

public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) {
    return new ScheduledThreadPoolExecutor(corePoolSize);
}

简而言之，您可以强制转换执行程序服务引用以调用该方法

ScheduledThreadPoolExecutor ex = (ScheduledThreadPoolExecutor) Executors.newScheduledThreadPool(5);
ex.setRemoveOnCancelPolicy(true);

或new ScheduledThreadPoolExecutor自己创建。

ScheduledThreadPoolExecutor ex = new ScheduledThreadPoolExecutor(5);
ex.setRemoveOnCancelPolicy(true);