摘要：如果發生了動作，則會從等待池當中喚醒一個線程重新恢復到狀態，如果是操作，則喚醒所有等待線程。當時間達到時觸發線程回到工作狀態。線程終止狀態線程結束了，就處于這種狀態，也就是方法運行完了。線程狀態切換詳細圖線程狀態源碼

還沒調用start，或者調用了start()方法，不一定立即改變線程狀態，中間可能需要一些步驟才完成一個線程的啟動。

start調用結束，線程由NEW變成RUNNABLE，存活著，并嘗試占用CPU資源，yield操作時，線程還是Runnable狀態，只是它有一個細節的內部變化，做一個簡單的讓步。在Java層面是Runnable的狀態，并不代表一定處于運行中的狀態，比如BIO中，線程正阻塞在網絡等待的時候，看到的狀態依然是Runnable狀態，而底層線程已經被阻塞住了。

線程被掛起了，原因通常是因為它在等待一個鎖，當某個synchronized正好有線程在使用時，一個線程嘗試進入這個臨界區，就會被阻塞，直到另一個線程走完臨界區或發生了相應鎖對象的wait操作后，它才有機會去爭奪進入臨界區的權利。當搶到鎖之后，才會從blocked狀態恢復到runnable狀態。這個狀態它好像什么也不做一樣。

當wait，join，park方法調用時，進入waiting狀態。前提是這個線程已經擁有鎖了。

blocked和waiting狀態的區別是：
A、blocked是虛擬機認為程序還不能進入某個區域，因為同時進去就會有問題，這是一塊臨界區。
B、發生wait等操作的先決條件是要進入臨界區，也就是線程已經拿到鎖了，自己可能進去做了一些事情，但此時通過判定業務上的參數，發現還有一些其他配合的資源沒有準備充分，那么自己就等等再做其他事情。

在waiting狀態下，如果發生了interrupt操作，則處于該狀態的線程在內部會拋出一個InterruptedException，這個異常應當在run方法內捕獲，使得run方法正常地執行完成，當然捕獲異常后，是決定讓線程繼續運行，還是結束等要根據業務場景才處理。

如果發生了notify動作，則會從等待池當中喚醒一個線程重新恢復到Runnable狀態，如果是notifyall操作，則喚醒所有等待線程。

通過wait(t),sleep(t),join(t),parkNanos,parkUntil等方法進入此狀態。當時間達到時觸發線程回到工作狀態Runnable。

interrupt只對處于waiting或timed_waiting狀態的線程起作用，對其他狀態不起作用。

線程結束了，就處于這種狀態，也就是run方法運行完了。這只是Java語言級別的一種狀態，在操作系統內部可能已經注銷了相應的線程，或者將它復用給其他需要使用線程的請求。

詳細圖

/**
     * A thread state.  A thread can be in one of the following states:
     * 

     * 
{@link #NEW}

     *     A thread that has not yet started is in this state.
     *     
     * 
{@link #RUNNABLE}

     *     A thread executing in the Java virtual machine is in this state.
     *     
     * 
{@link #BLOCKED}

     *     A thread that is blocked waiting for a monitor lock
     *     is in this state.
     *     
     * 
{@link #WAITING}

     *     A thread that is waiting indefinitely for another thread to
     *     perform a particular action is in this state.
     *     
     * 
{@link #TIMED_WAITING}

     *     A thread that is waiting for another thread to perform an action
     *     for up to a specified waiting time is in this state.
     *     
     * 
{@link #TERMINATED}

     *     A thread that has exited is in this state.
     *     
     * 
     *
     * 

     * A thread can be in only one state at a given point in time.
     * These states are virtual machine states which do not reflect
     * any operating system thread states.
     *
     * @since   1.5
     * @see #getState
     */
    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:
         * 

         *   
{@link Object#wait() Object.wait} with no timeout
         *   
{@link #join() Thread.join} with no timeout
         *   
{@link LockSupport#park() LockSupport.park}
         * 
         *
         * 
A thread in the waiting state is waiting for another thread to
         * perform a particular action.
         *
         * For example, a thread that has called Object.wait()
         * on an object is waiting for another thread to call
         * Object.notify() or Object.notifyAll() on
         * that object. A thread that has called Thread.join()
         * 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:
         * 

         *   
{@link #sleep Thread.sleep}
         *   
{@link Object#wait(long) Object.wait} with timeout
         *   
{@link #join(long) Thread.join} with timeout
         *   
{@link LockSupport#parkNanos LockSupport.parkNanos}
         *   
{@link LockSupport#parkUntil LockSupport.parkUntil}
         * 
         */
        TIMED_WAITING,
        /**
         * Thread state for a terminated thread.
         * The thread has completed execution.
         */
        TERMINATED;
    }