运行和启动线程的区别 [英] Difference between running and starting a thread

问题描述

我不明白启动和运行线程之间的区别，我测试了这两种方法并且它们输出相同的结果，首先我使用了 run() 的组合并在同一线程上启动并且它们执行相同的功能如下:

i don't understand the difference between starting and running a thread, i tested the both methods and they outputs the same result, first i used a combination of run() and start on the same thread and they did the same function as follows:

public class TestRunAndStart implements Runnable {
public void run() {
    System.out.println("running");
}
public static void main(String[] args) {
     Thread t = new Thread(new TestRunAndStart());
     t.run();
     t.run();
     t.start(); 
}

}

输出为:

running
running
running

然后我看到 run() 方法的 javadoc 说:如果这个线程是使用一个单独的 Runnable run 对象构造的，那么该 Runnable 对象的 run 方法被调用；否则，此方法不执行任何操作并返回，因此我尝试使用 run() 方法而不使用单独的可运行对象，如下所示:

then i saw the javadoc of the run() method said that: If this thread was constructed using a separate Runnable run object, then that Runnable object's run method is called; otherwise, this method does nothing and returns so i tried to use the run() method without a separate runnable as follows :

public class TestRun extends Thread {
public void run(){
    System.out.println("Running Normal Thread");
}
public static void main(String[]args){
    TestRun TR=new TestRun();
    TR.run();
   }

}

并且它还执行 run() 方法并打印 Running Normal Thread 尽管它是在没有单独的 runnable 的情况下构建的！那么这两种方法的主要区别是什么

and it also executes the run() method and prints Running Normal Thread although it's constructed without a separate runnable! so what's the main difference between the two methods

推荐答案

Thread.run() 不会产生新线程，而 Thread.start() 会，即 Thread.run 实际上与调用者在同一个线程上运行，而 Thread.start() 创建一个新的线程来运行任务.

Thread.run() does not spawn a new thread whereas Thread.start() does, i.e Thread.run actually runs on the same thread as that of the caller whereas Thread.start() creates a new thread on which the task is run.

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