java基础专题：3. java线程的状态

常规的说法，线程是有new，runnable，running，blocked，terminated五种状态。
但是java代码Thread类中定义的state枚举中, 其实有NEW，RUNNABLE，BLOCKED，WAITING，TIMED_WAITING，TERMINATED这6种。是没有running的，见代码

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;
    }

主要说说BLOCKED，WAITING，TIMED_WAITING的区别，最好是自己看英文注释，很清楚的。
BLOCKED 状态是等待一个monitor lock，其实就是等待进入synchronized代码块或者方法
WAITING 状态是Object.wat() Thread.join() LockSupport.park()方法之后，也就是不带超时时间的这些方法
TIMED_WAITING跟WAITING 的区别就是带了超时时间，Object.wat(n) Thread.join(n) LockSupport.parkNanos LockSupport.parkUntil等
通俗的讲就是，这三种都是阻塞，不需要别的线程来唤醒的，就是BLOCKED
需要别的线程来notify或者unpark的，就是WAITING 或者TIMED_WAITING