如何在启动一定次数后或返回特定值时停止 ScheduledExecutorService？

Question

I use a ScheduledExecutorService to execute 2 tasks at a fixed rate scheduleAtFixedRate . Both of these tasks return a value. How to stop execution of a task after a certain number of starts or when a certain value returns? Or maybe there are more suitable tools for this?

Answer 1

1. Once you submit task to ScheduledExecutorService, if task complete it's jobs then the task/thread automatically stop by the JVM.
2. If task takes to long to respond or you want stop in middle of execution, you can interrupt task/thread using future.cancel(true).
3. At the end you should shutdown ScheduledExecutorService by calling shutdown method on it.

Hope below code help you,

    ScheduledExecutorService service = Executors.newScheduledThreadPool(2);//pool size
    Callable<String> task = () -> {
        return "task1 completed";
    };
    String taskResponse = null;
    Future<String> future = service.submit(task);
    // Application thread wait for task to complete.
    while (!future.isDone()){
        // wait specific time or you can interrupt thread/task as below
        //future.cancel(true), it will interrupt task/thread.
    }
    if(future.isDone()){
        taskResponse = future.get();
    }
    // at end call Executor service shutdown
    service.shutdown();// you can do the same at finally block also.