线程的状态流转

从JAVA源码可以得出有6种状态

NEW、RUNNABLE、BLOCKED、WAITING、TIME_WAITING、TERMINATED

通过代码解释说明

1. 初始化状态是NEW

   public static void main(String[] args) throws InterruptedException { Thread thread = new Thread(() -> {});  System.out.println(thread.getState());
   }
   

   执行结果

   NEW
   

2. 运行过程的状态是RUNABLE

   public static void main(String[] args) throws InterruptedException {  Thread thread = new Thread(() -> {  while (true) { }  });  thread.start();  Thread.sleep(500);  System.out.println(thread.getState());  
   }
   

   执行结果的确是RUNNABLE

   RUNNABLE
   

3. 主线程被上锁了，创建的线程无法获取锁，此时的状态是BLOCKED

   public class ThreadStatus {  public static Object obj = new Object();  public static void main(String[] args) throws InterruptedException {  Thread thread = new Thread(() -> {  synchronized (obj) {  while (true){  }  }  });  // 此时住线程持有锁  synchronized (obj){  // 开启新的线程，因为主线程持有锁所以拿不到锁被阻塞  thread.start();  Thread.sleep(500);  System.out.println(thread.getState());  }  }
   }
   

   执行结果是BLOCKED

   BLOCKED
   

4. 当创建的线程持有锁时状态是WAITING，

   public class ThreadStatus {  public static Object obj = new Object();  public static void main(String[] args) throws InterruptedException {Object obj = new Object();Thread thread = new Thread(() -> {synchronized (obj) {  // 步骤2：新线程获取锁try {obj.wait();   // 步骤3：释放锁，进入WAITING状态} catch (InterruptedException e) {throw new RuntimeException(e);}// 步骤6：被唤醒后重新获取锁，继续执行}});thread.start();           // 步骤1：启动新线程Thread.sleep(500);        // 步骤4：主线程睡眠System.out.println(thread.getState());  // 输出：WAITINGsynchronized (obj) {      // 步骤5：主线程可以获取锁（因为新线程已释放）obj.notify();         // 唤醒新线程}                         // 主线程释放锁Thread.sleep(500);System.out.println(thread.getState());  // 输出：TERMINATED}  
   }
   

   执行结果是

   WAITING
   TERMINATED
   

5. 当线程处于休眠(sleep())中，状态即为TIMED_WAITING

   public static void main(String[] args) throws InterruptedException {  Thread thread = new Thread(() -> {  try {  Thread.sleep(10000);  } catch (InterruptedException e) {  throw new RuntimeException(e);  }  });  thread.start();  Thread.sleep(500);  System.out.println(thread.getState());  
   }
   

   执行结果是

   TIMED_WAITING
   

6. 线程执行结束后状态即为TERMINATED

   public static void main(String[] args) throws InterruptedException {  Thread thread = new Thread(() -> {  try {  Thread.sleep(300);  } catch (InterruptedException e) {  throw new RuntimeException(e);  }  });  thread.start();  Thread.sleep(500);  System.out.println(thread.getState());  
   }
   

   执行结果

   TERMINATED