目录
1、Java线程6中状态
Java线程一共分为6种状态，如下所示
- NEW：新建状态
- RUNNABLE：就绪状态
- BLOCKED：阻塞状态
- WAITING：等待状态
- TIMED_WAITING：限时等待状态
- TERMINATED：结束状态
2、Tread类中State枚举定义的6种状态
通过Tread中的State枚举查看这六种状态的定义，如下所示：
public enum State {
/**
* Thread state for a thread which has not yet started.
*/
NEW,
/**
* Thread state for a runnable thread. A thread in the runnable
* state is executing in the Java virtual machine but it may
* be waiting for other resources from the operating system
* such as processor.
*/
RUNNABLE,
/**
* Thread state for a thread blocked waiting for a monitor lock.
* A thread in the blocked state is waiting for a monitor lock
* to enter a synchronized block/method or
* reenter a synchronized block/method after calling
* {@link Object#wait() Object.wait}.
*/
BLOCKED,
/**
* Thread state for a waiting thread.
* A thread is in the waiting state due to calling one of the
* following methods:
* <ul>
* <li>{@link Object#wait() Object.wait} with no timeout</li>
* <li>{@link #join() Thread.join} with no timeout</li>
* <li>{@link LockSupport#park() LockSupport.park}</li>
* </ul>
*
* <p>A thread in the waiting state is waiting for another thread to
* perform a particular action.
*
* For example, a thread that has called <tt>Object.wait()</tt>
* on an object is waiting for another thread to call
* <tt>Object.notify()</tt> or <tt>Object.notifyAll()</tt> on
* that object. A thread that has called <tt>Thread.join()</tt>
* is waiting for a specified thread to terminate.
*/
WAITING,
/**
* Thread state for a waiting thread with a specified waiting time.
* A thread is in the timed waiting state due to calling one of
* the following methods with a specified positive waiting time:
* <ul>
* <li>{@link #sleep Thread.sleep}</li>
* <li>{@link Object#wait(long) Object.wait} with timeout</li>
* <li>{@link #join(long) Thread.join} with timeout</li>
* <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
* <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
* </ul>
*/
TIMED_WAITING,
/**
* Thread state for a terminated thread.
* The thread has completed execution.
*/
TERMINATED;
}
3、各种状态的图解
各种状态图解，如下图所示：
4、各种状态的解释
-
NEW状态
表示刚刚创建的线程，这种线程还没开始执行。等到线程的start()方法调用时，才表示线程开始执行。 -
RUNNABLE状态
表示线程所需的一切资源都已经准备好了。处于就绪状态的线程，只是说明此线程已经做好了被运行的准备，随时等待CPU调度执行，而并不是说调用了start()方法，这个线程就会被立即运行。 -
BLOCKED状态
如果线程在执行过程中遇到了synchronized或者Lock，那么就会进入到阻塞状态。处于阻塞状态的线程会放弃对CPU的使用权，停止执行，直到次线程进入到了就绪的状态，才会有机会再次被CPU调用运行。 -
WAITING状态
如果线程被调用了没有超时时间的wait方法，那么会进入无限等待状态。直到被notify通知才可以继续执行。 -
TIMED_WAITING状态
与WAITING状态相似，区别是，在有限的时间内进行线程等待。