为什么不让线程同时运行? [英] Why arent the threads running concurrently?

问题描述

我正在运行一个非常简单的多线程程序

I am running a very simple multi thread program

主程序

package javathread;


public class JavaThread {


    public static void main(String[] args) 
    {

        JThread t1 = new JThread(10,1);
        JThread t2 = new JThread(10,2);

        t1.run();
        t2.run();

    }
}

JThread.java

package javathread;

import java.util.Random;

public class JThread implements Runnable
{
    JThread(int limit , int threadno)
    {
        t = new Thread();
        this.limit = limit;
        this.threadno = threadno;

    }

    public void run()
    {
        Random generator = new Random();

        for (int i=0;i<this.limit;i++)
        {
            int num = generator.nextInt();

            System.out.println("Thread " + threadno + " : The num is " + num   );
            try
            {
            Thread.sleep(100);
            }
            catch (InterruptedException ie)
            {

            }
        }

    }




    Thread t;
    private int limit;
    int threadno;
}

我希望两个线程同时运行/并行运行，类似于此图片

I expect both threads to run concurrently/parrallel , something similar to this picture

相反，我在线程1首先运行然后线程2运行的地方得到这个信息

Instead I am getting this where thread 1 runs first then thread 2 runs

有人可以向我解释为什么会这样吗?

我如何使线程同时运行?

推荐答案

因为您调用了t1.run()和t2.run()而不是t1.start()和t2.start().

Because you called t1.run() and t2.run() instead of t1.start() and t2.start().

如果您调用run，那只是一个普通的方法调用.就像任何方法一样，它直到完成才返回.它不会同时运行任何东西. run绝对没有什么特别的.

If you call run, it's just a normal method call. It doesn't return until it's finished, just like any method. It does not run anything concurrently. There is absolutely nothing special about run.

start是用于启动另一个线程并在新线程中调用run的魔术"方法. (顺便说一句，调用start也是正常的方法调用.start中的代码起到了神奇的作用)

start is the "magic" method that you call to start another thread and call run in the new thread. (Calling start is also a normal method call, by the way. It's the code inside start that does the magic)

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