Java Thread类的join（）方法小结

Java Thread类的join（）方法小结2011-06-21 BlogJava Allen Yu最近在编程遇到了个需要异步执行的操作,经过了一番折腾,发现在主子线程操作中join（）方法是非常实用且有效的一个方法.

先来看join（）及其重载（overload）方法的说明和代码:

join（）方法:

 1     /**
  2      * Waits for this thread to die.
  3      *
  4      * @exception  InterruptedException if another  thread has interrupted
  5      *             the current thread.   The <i>interrupted status</i> of the
  6      *             current thread is  cleared when this exception is thrown.
  7      */
  8     public final void join（） throws  InterruptedException {
  9         join（0）;
10     }

join（long millis）方法:

1     /**
  2      * Waits at most <code>millis</code>  milliseconds for this thread to
  3      * die. A timeout of <code>0</code>  means to wait forever.
  4      *
  5      * @param      millis   the time to wait  in milliseconds.
  6      * @exception  InterruptedException if another  thread has interrupted
  7      *             the current thread.   The <i>interrupted status</i> of the
  8      *             current thread is  cleared when this exception is thrown.
  9      */
10     public final synchronized void join（long millis） throws InterruptedException {
11
12         long base = System.currentTimeMillis（）;
13         long now = 0;
14
15         if （millis < 0） {
16             throw new IllegalArgumentException （"timeout value is negative"）;
17         }
18
19         if （millis == 0） {
20             while （isAlive（）） {
21                 wait（0）;
22             }
23         } else {
24             while （isAlive（）） {
25                 long delay = millis -  now;
26                 if （delay <= 0） {
27                     break;
28                 }
29                 wait（delay）;
30                 now = System.currentTimeMillis （） - base;
31             }
32         }
33     }