Java线程InterruptedException块未执行答案

【问题标题】：Java thread InterruptedException block not executingJava线程InterruptedException块未执行
【发布时间】：2021-03-19 15:57:50
【问题描述】：

我的 Java 类如下所示。这是一个测试线程加入（等待）和线程睡眠（定时等待）的小练习。

public class BasicThreadTest {

    public static void main(String[] args) {
        testThreadWait();
        System.out.println(Thread.currentThread().getName() + " exiting");
    }

    private static void testThreadWait() {
        Thread thread1 = new Thread(() -> {
            String currentThread = Thread.currentThread().getName();
            System.out.println(String.format("%s execution started", currentThread));
            long waitMillis = 20000L;
            try {
                System.out.println(String.format("%s going for timed wait of %d millis", currentThread, waitMillis));
                Thread.sleep(waitMillis);
            } catch (InterruptedException e) {
                System.out.println(String.format("%s timed wait over after %d millis", currentThread, waitMillis));
            }
            System.out.println(String.format("%s execution ending", currentThread));
        });
        thread1.setName("Thread-1");

        Thread thread2 = new Thread(() -> {
            String currentThread = Thread.currentThread().getName();
            System.out.println(String.format("%s execution started", currentThread));
            try {
                System.out.println(currentThread + " about to wait for " + thread1.getName());
                thread1.join();
            } catch (InterruptedException e) {
                System.out.println(String.format("%s wait over for %s", currentThread, thread1.getName()));
            }
            System.out.println(String.format("%s execution ending", currentThread));
        });
        thread2.setName("Thread-2");

        thread2.start();
        thread1.start();
    }
}

无论我以什么顺序启动两个线程，我都不会在sleep() 或join() 中执行两个InterruptedException 块。下面是一个示例输出：

Thread-2 execution started
Thread-2 about to wait for Thread-1
main exiting
Thread-1 execution started
Thread-1 going for timed wait of 20000 millis
Thread-1 execution ending
Thread-2 execution ending

有什么解释为什么会这样吗？

【问题讨论】：

你在哪里中断线程？如果您不真正打断他们，您将不会收到InterruptedException。
有道理，我曾假设一旦等待或定时等待结束，InterruptedException 总是会被抛出。情况并非如此，看起来必须明确调用interrupt()。

标签： java multithreading interrupted-exception

【解决方案1】：

当块（或等待）完成时，wait() 不会抛出 InterruptedException。

如果您启动调用thread1.interrupt() 的第三个线程，那么您将获得InterruptedException。

【讨论】：

【解决方案2】：

如果您实际上不中断线程，您将不会收到InterruptedException。

你可以试试，例如：

    thread2.start();
    thread1.start();
    
    Thread.sleep(1000);

    thread1.interrupt();
    thread2.interrupt();

Ideone demo

输出：

Thread-2 execution started
Thread-1 execution started
Thread-1 going for timed wait of 20000 millis
Thread-2 about to wait for Thread-1
Thread-1 timed wait over after 20000 millis
Thread-1 execution ending
Thread-2 wait over for Thread-1
Thread-2 execution ending
main exiting

【讨论】：