java - Java 创建 Thread 实例时会发生什么

Question

我有关于 Java 线程和操作系统线程的问题，我阅读了 Java Threads vs Pthreads和 Java Threads vs OS Threads但我没有找到解决我困惑的答案。

在调用start()之前我考虑过，没有创建操作系统线程。

但是根据https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.State.html ,

A thread that has not yet started is in NEW state.

我错了吗，还是java doc中定义的状态不仅仅用于标记Thread实例的状态？

我的问题是:

• 当我们创建 Thread 实例但在调用 start() 之前到底发生了什么
• Java 中何时真正创建操作系统线程

Answer 1

Thread thread = new Thread(){
    @Override
    public void run() {
        // code
    }
}; 
// at this point the thread is in NEW state, all you have a simple java object, 
// no actual thread is created

thread.start();
// when start() is invoked, at some unspecified point in the near future 
// the thread will go into RUNNABLE state, this means an actual thread will be created.  
// That can happen before start() returns.