线程状态的观察方式

Thread类下有一个枚举enum类型的变量State,共有六个值

 public enum State {
        
        NEW,

        RUNNABLE,

       
        BLOCKED,

       
        WAITING,

       
        TIMED_WAITING,

        
        TERMINATED;
    }

NEW对应创建状态。
RUNNABLE对应就绪状态
BLOCKED,WAITING,TIMED_WAITING对应阻塞状态
TERMINATED对应结束状态

package com.design;

public class SeeState implements Runnable{
    @Override
    public void run() {

            try {
                Thread.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

    }

    public static void main(String[] args) {
        Thread thread = new Thread(new SeeState());
        Thread.State state = thread.getState();
        System.out.println(state);
        thread.start();
        state = thread.getState();
        System.out.println(state);
        while (thread.getState()!=Thread.State.TERMINATED)
        {
            state = thread.getState();
            System.out.println(state);
        }
        
    }
}

1. 初始化线程后立刻执行getState方法得到的是NEW
2. 调用线程的start方法之后再执行getState方法得到的是RUNNABLE
3. 线程休眠时得到的State是TIMED_WATING
4. 线程结束后倘若再次调用start方法则会抛出异常并显示TERMINED