调用 start 方法两次答案

【问题标题】：Call start method two times调用 start 方法两次
【发布时间】：2014-10-05 12:55:53
【问题描述】：

为什么下面的代码会抛出异常？

class MyThread extends Thread 
{
    public static void main (String [] args) 
    {
        MyThread t = new MyThread();
        t.start();
        System.out.print("one. ");
        t.start();
        System.out.print("two. ");
    }

    public void run() 
    {
        System.out.print("Thread ");
    }
}

你能告诉我JLS吗？

【问题讨论】：

懒惰的问题。阅读 javadoc。

标签： java multithreading

【解决方案1】：

这就是start() 方法的约定：

public void start()

Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread.

The result is that two threads are running concurrently: the current thread (which returns from the call to the start method) and the other thread (which executes its run method).

It is never legal to start a thread more than once. In particular, a thread may not be restarted once it has completed execution.

Throws:
    IllegalThreadStateException - if the thread was already started.

你不能启动一个线程两次。

【讨论】：

【解决方案2】：

正如其他回复所说，您不能两次启动线程。但是，也许您想要做的是启动 2 个线程：在这种情况下，只需再次实例化您的线程对象：

    MyThread t = new MyThread();
    t.start();
    System.out.print("one. ");
    MyThread t2 = new MyThread();
    t2.start();
    System.out.print("two. ");

【讨论】：