《Java编程思想第四版》学习笔记51--关于线程组的控制

//: ThreadGroup1.java
// How thread groups control priorities
// of the threads inside them.
public class ThreadGroup1 {
 public static void main(String[] args) {
 // Get the system thread & print its Info:
 ThreadGroup sys = 
 Thread.currentThread().getThreadGroup();
 sys.list(); // (1)
 // Reduce the system thread group priority:
 sys.setMaxPriority(Thread.MAX_PRIORITY - 1);
 // Increase the main thread priority:
 Thread curr = Thread.currentThread();
 curr.setPriority(curr.getPriority() + 1);
 sys.list(); // (2)
 // Attempt to set a new group to the max:
 ThreadGroup g1 = new ThreadGroup("g1");
 g1.setMaxPriority(Thread.MAX_PRIORITY);
 // Attempt to set a new thread to the max:
 Thread t = new Thread(g1, "A");
 t.setPriority(Thread.MAX_PRIORITY);
 g1.list(); // (3)
 // Reduce g1's max priority, then attempt
 // to increase it:
 g1.setMaxPriority(Thread.MAX_PRIORITY - 2);
 g1.setMaxPriority(Thread.MAX_PRIORITY);
 g1.list(); // (4)
 // Attempt to set a new thread to the max:
 t = new Thread(g1, "B");
 t.setPriority(Thread.MAX_PRIORITY);
 g1.list(); // (5)
 // Lower the max priority below the default
 // thread priority:
 g1.setMaxPriority(Thread.MIN_PRIORITY + 2);
 // Look at a new thread's priority before
 // and after changing it:
 t = new Thread(g1, "C");
 g1.list(); // (6)
 t.setPriority(t.getPriority() -1);
 g1.list(); // (7)
 // Make g2 a child Threadgroup of g1 and
 // try to increase its priority:
 ThreadGroup g2 = new ThreadGroup(g1, "g2");
 g2.list(); // (8)
 g2.setMaxPriority(Thread.MAX_PRIORITY);
 g2.list(); // (9)
 // Add a bunch of new threads to g2:
 for (int i = 0; i < 5; i++)
 new Thread(g2, Integer.toString(i));
 // Show information about all threadgroups
 // and threads:
 sys.list(); // (10)
 System.out.println("Starting all threads:");
 Thread[] all = new Thread[sys.activeCount()];
 sys.enumerate(all);
 for(int i = 0; i < all.length; i++)
 if(!all[i].isAlive())
 all[i].start();
 // Suspends & Stops all threads in 
 // this group and its subgroups:
 System.out.println("All threads started");
 sys.suspend(); // Deprecated in Java 1.2
 // Never gets here...
 System.out.println("All threads suspended");
 sys.stop(); // Deprecated in Java 1.2
 System.out.println("All threads stopped");
 }
} ///:~

 P.527的这个例程运行结果和书上的不一致，不知道是什么原因。