java - 执行程序终止和关闭之间的区别

Question

我想等待我所有的线程都被执行，然后才继续。

ExecutorService es = Executors.newFixedThreadPool(3);
List<Callable<Void>> calls = new LinkedList<>();

Arrays.stream(new int[]{1,2,3})
        .forEach( i -> calls.add(() -> {
            someFunc(i);
            return null;
        }));

try {
    es.invokeAll(calls);
} catch (InterruptedException e) {
    e.printStackTrace();
}

es.shutdown();

System.out.println(es.isTerminated()); //prints false
System.out.println(es.isShutdown()); //prints true

为什么我在这两种情况下都没有得到 true？

我的所有线程都已成功终止。

Answer 1

查看 isTerminated 的文档突出了区别:

Returns true if all tasks have completed following shut down. Note that isTerminated() is never true unless either shutdown() or shutdownNow() was called first.

@return true if all tasks have completed following shut down

因此在您的情况下，这意味着执行程序已关闭但您的任务未完成。