Oracle JDK 定义中,线程一共有六种状态
https://docs.oracle.com/javase/8/docs/api/java/lang/Thread.State.html
NEW:未启动状态
Thread t = new Thread() { @Override public void run() { System.out.println(Thread.currentThread().getName()); } }; System.out.println(t.getState().name());
RUNNABLE:可运行状态
处于可运行状态的线程正在 Java 虚拟机中执行,但也可能是正在等待来自操作系统资源,例如 CPU。
Thread t = new Thread() { @Override public void run() { System.out.println(Thread.currentThread().getName()); } }; t.start(); System.out.println(t.getState().name());
BLOCKED:阻塞状态
final Object lock = new Object(); Thread t = new Thread() { @Override public void run() { synchronized (lock) { System.out.println(Thread.currentThread().getName()); } } }; synchronized (lock) { try { t.start(); Thread.sleep(1000); System.out.println(t.getState().name()); } catch (InterruptedException e) { e.printStackTrace(); } }
WAITING:等待状态
调用以下方法,使线程处于等待状态:
Object.wait()、Thread.join()、LockSupport.park()
另一个线程调用以下方法,使线程继续执行:
Object.notify()、 Object.notifyAll()、Thread.join()
final Object lock = new Object(); Thread t = new Thread() { @Override public void run() { try { synchronized (lock) { lock.wait(); System.out.println(Thread.currentThread().getName()); } } catch (InterruptedException e) { e.printStackTrace(); } } }; t.start(); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } synchronized (lock) { System.out.println(t.getState().name()); lock.notifyAll(); }
TIMED_WAITING:具有指定时间的等待状态
调用以下方法,使线程处于指定时间的等待状态:
Thread.sleep()、Object.wait()、Thread.join()、LockSupport.parkNanos()、LockSupport.parkUntil()
Thread t = new Thread() { @Override public void run() { try { Thread.sleep(2000); System.out.println(Thread.currentThread().getName()); } catch (InterruptedException e) { e.printStackTrace(); } } }; t.start(); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(t.getState().name());
TERMINATED:已终止线程的线程状态或线程已完成执行
Thread t = new Thread() { @Override public void run() { System.out.println(Thread.currentThread().getName()); } }; t.start(); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println(t.getState().name());
线程的状态图