在Java中,线程有以下六种状态:
- NEW:新建状态,表示线程对象已经被创建但还未启动。
- RUNNABLE:可运行状态,表示线程处于就绪状态,等待系统分配CPU资源执行。
- BLOCKED:阻塞状态,表示线程被挂起,暂时无法执行,可能是在等待某个资源(如I/O操作、获取锁)的过程中。
- WAITING:等待状态,表示线程正在等待另一个线程执行特定操作。
- TIMED_WAITING:计时等待状态,表示线程在等待特定时间内执行某个操作。
- TERMINATED:终止状态,表示线程已经执行完任务或者因异常而结束。
这些状态构成了线程的生命周期,在不同的状态间切换,线程会执行不同的行为和任务。理解线程的状态对于编写多线程程序非常重要,可以帮助你控制线程的行为和逻辑。
在 java.lang.Thread.State 这个枚举中给出了六种线程状态:
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; }
这里先列出各个线程状态发生的条件,下面将会对每种状态进行详细解析
注意:6种状态是不包含运行状态的.