JUC是什么？

1. public enum State {
2. /**
3.          * Thread state for a thread which has not yet started.
4.          */
5.         NEW,(新建) 
6. 
7. 
8. /**
9.          * Thread state for a runnable thread.  A thread in the runnable
10.          * state is executing in the Java virtual machine but it may
11.          * be waiting for other resources from the operating system
12.          * such as processor.
13.          */
14.         RUNNABLE,（准备就绪） 
15. 
16. /**
17.          * Thread state for a thread blocked waiting for a monitor lock.
18.          * A thread in the blocked state is waiting for a monitor lock
19.          * to enter a synchronized block/method or
20.          * reenter a synchronized block/method after calling
21.          * {@link Object#wait() Object.wait}.
22.          */
23.         BLOCKED,（阻塞）
24. 
25. /**
26.          * Thread state for a waiting thread.
27.          * A thread is in the waiting state due to calling one of the
28.          * following methods:
29.          * <ul>
30.          *   <li>{@link Object#wait() Object.wait} with no timeout</li>
31.          *   <li>{@link #join() Thread.join} with no timeout</li>
32.          *   <li>{@link LockSupport#park() LockSupport.park}</li>
33.          * </ul>
34.          *
35.          * <p>A thread in the waiting state is waiting for another thread to
36.          * perform a particular action.
37.          *
38.          * For example, a thread that has called <tt>Object.wait()</tt>
39.          * on an object is waiting for another thread to call
40.          * <tt>Object.notify()</tt> or <tt>Object.notifyAll()</tt> on
41.          * that object. A thread that has called <tt>Thread.join()</tt>
42.          * is waiting for a specified thread to terminate.
43.          */
44.         WAITING,（不见不散）
45. 
46. /**
47.          * Thread state for a waiting thread with a specified waiting time.
48.          * A thread is in the timed waiting state due to calling one of
49.          * the following methods with a specified positive waiting time:
50.          * <ul>
51.          *   <li>{@link #sleep Thread.sleep}</li>
52.          *   <li>{@link Object#wait(long) Object.wait} with timeout</li>
53.          *   <li>{@link #join(long) Thread.join} with timeout</li>
54.          *   <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
55.          *   <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
56.          * </ul>
57.          */
58.         TIMED_WAITING,（过时不候）
59. 
60. /**
61.          * Thread state for a terminated thread.
62.          * The thread has completed execution.
63.          */
64.         TERMINATED;(终结)
65.     }

1. public final void setDaemon(boolean on) {
2.         checkAccess();
3. if (isAlive()) {
4. throw new IllegalThreadStateException();
5.         }
6.         daemon = on;
7.     }