Java多线程 线程状态原理详解

/**
 * 多线程运行状态切换示例
 */
public class Demo2 {

  public static void main(String[] args) throws Exception{
    //第一种状态切换 新建->运行->终止
    System.out.println("###第一种状态切换 新建->运行->终止###");
    Thread thread1 = new Thread(()->{
      System.out.println("thread1当前状态：" + Thread.currentThread().getState());
      System.out.println("thread1执行完毕");
    });
    System.out.println("调用start之前，thread1当前状态：" + thread1.getState());
    thread1.start();
    Thread.sleep(2000L);  //等待thread1执行结束
    System.out.println("等待thread1执行结束，当前状态：" + thread1.getState());
    System.out.println();
//    thread1.start();    //此时会抛出java.lang.IllegalThreadStateException

    //第二种状态切换 新建->运行->等待->运行->终止
    System.out.println("###第二种状态切换 新建->运行->等待->运行->终止###");
    Thread thread2 = new Thread(()->{
      try {
        Thread.sleep(1500L);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
      System.out.println("thread2当前状态：" + Thread.currentThread().getState());
      System.out.println("thread2执行完毕");
    });
    System.out.println("调用start之前，thread2当前状态：" + thread2.getState());
    thread2.start();
    System.out.println("调用start之后，thread2当前状态：" + thread2.getState());
    Thread.sleep(200L);  //等待一段时间令thread2进入sleep方法
    System.out.println("调用start之后，等待200毫秒，thread2当前状态：" + thread2.getState());
    Thread.sleep(2000L);  //等待thread2执行结束
    System.out.println("等待thread2执行结束，当前状态：" + thread2.getState());
    System.out.println();

    //第三种状态切换 新建->运行->阻塞->运行->终止
    System.out.println("###第三种状态切换 新建->运行->阻塞->运行->终止###");
    Thread thread3 = new Thread(()->{
      synchronized (Demo2.class){
        System.out.println("thread3当前状态：" + Thread.currentThread().getState());
        System.out.println("thread3执行完毕");
      }
    });
    synchronized (Demo2.class){
      System.out.println("调用start之前，thread3当前状态：" + thread3.getState());
      thread3.start();
      System.out.println("调用start之后，thread3当前状态：" + thread3.getState());
      Thread.sleep(200L);
      System.out.println("等待200毫秒，thread3等待获取锁，thread3当前状态：" + thread3.getState());
    }
    Thread.sleep(1000L);    //等待thread3执行完毕
    System.out.println("等待1秒，令thread3获取锁后执行方法，thread3当前状态：" + thread3.getState());
  }
}