java thread start run 的区别和联系

java thread start run 的区别和联系如下，摘取一段外文网站论坛上的解释，它讲的不错。一句话，run()是顺序执行而start()则是并行执行。

Why do we need start() method in Thread class? In Java API description for Thread class is written : "Java Virtual Machine calls the run method of this thread..".

Couldn't we call method run() ourselves, without doing double call: first we call start() method which calls run() method? What is a meaning to do things such complicate?

 

There is some very small but important difference between using start() and run() methods. Look at two examples below:

Example one:

Code:

Thread one = new Thread();
Thread two = new Thread();
one.run();
two.run();

Example two:

Code:

Thread one = new Thread();
Thread two = new Thread();
one.start();
two.start();

The result of running examples will be different.

In Example one the threads will run sequentially: first, thread number one runs, when it exits the thread number two starts.

In Example two both threads start and run simultaneously.

Conclusion: the start() method call run() method asynchronously (does not wait for any result, just fire up an action), while we run run() method synchronously - we wait when it quits and only then we can run the next line of our code.