多线程Java，但只有一个线程工作 [英] Multi Thread Java, but only one thread working

问题描述

My Java Threads不能独立工作，如何解决？这是最初的主要内容：

My Java Threads does not work independently, how to fix it? This is the initial main:

Mechanics mechanics = new Mechanics(busShop, "Mechanic 1");
Mechanics mechanics2 = new Mechanics(busShop, "Mechanic 2");

Thread thMechanic = new Thread(mechanics);
Thread thMehanic2 = new Thread(mechanics2);

thMechanic.start();
thMehanic2.start();

到目前为止没问题，按预期工作，所以机制师这样做：

No problem so far, work as expected, so the mechanics do this:

public void run() {
    fixEngine();
}

private void fixEngine() {
    while (true) {
        busShop.FixEngine(MechanicsName);
    }
}

如此处所示它可以永久修复引擎，Inside修复引擎功能：

As seen here it works to fix engine forever, Inside the fix engine function:

public static List<Bus> ListBusEngineFix = new LinkedList();

 public void FixEngine(String mechanicsName) {
        Bus bus;

        synchronized (ListBusEngineFix) {
            System.out.println("Working Thread: " + Thread.currentThread().getName());
            while (ListBusEngineFix.size() == 0) {
                try {
                    ListBusEngineFix.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
        //Wait for notify if empty

        try {
            Thread.sleep(10000);

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //IF EACH THREAD RUNS INDEPENDENTLY IT WILL BT ONLY LESS THAN 20 SECONDS
        //BUT THIS CASE, MY PROGRAM WAIT FOR PREVIOUS THREAD, WHICH CAUSE MORE THAN 20 SECONDS.
}

结果如下：

Working Thread: Thread-6
Working Thread: Thread-7

两个线程都按预期运行

前10秒：

Bus: Bus 1by Mechanic 1

另外10秒：

Bus: Bus 2by Mechanic 1

我的怀疑是机械师1（线程）锁定本身，因此机械师2（线程）无法帮助它，因为机械师1完成所有任务。无论如何，如何解决它？

My suspicion would be Mechanic 1 (Thread) lock itself so that Mechanic 2 (Thread) cannot help it, as the Mechanic 1 do all the task. Anyway, how to fix it?

注意：我只在早期使用synchronized进行等待（通知），如果我不说它会有网络监控异常。

Note: I only use synchronized in the early for wait (for notification), If I don't put it will have network monitoring exception.

编辑：添加了LinkedList和Notify以便澄清，所提供的所有列表都是链接列表。一个班级。

Added LinkedList and Notify for clarification, all of the List provided is Linked List. an Class.

编辑2：
好​​的我已修好如下：

EDIT 2: Ok I have fixed into like this:

synchronized (ListBusDepotWaiting) {
    while (ListBusDepotWaiting.size() == 0) {
        try {
            ListBusDepotWaiting.wait();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

//Engine not yet fixed
//Notify the Mechanics to fix car
if (ListBusEngineFix.size() < 2) {
    //Means that mechanics is empty
    bus = (Bus) ((LinkedList<?>) ListBusDepotWaiting).poll();
    ((LinkedList<Bus>) ListBusEngineFix).offer(bus);
    if (ListBusEngineFix.size() == 1) {
        synchronized (ListBusEngineFix) {
            ListBusEngineFix.notify();
        }
    }

}

现在他们现在可以打电话和通知，但原来的问题仍然存在，无法将工作交给 Mechanic2

Now they can call and notify now, but the original problem still exists, which is unable to give work to Mechanic2

推荐答案

应该在同一个monotor对象上执行 wait 和 notify 。

The wait and notify should be performed on the same monotor object.

在您的代码中，您正在等待

In your code, you are waiting on

ListBusEngineFix.wait（）;

而通过

BusShop.ListBusDepotWaiting.notify（）;

因此等待线程将被阻止。

So the waiting thread will be blocked.

这篇关于多线程Java，但只有一个线程工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！