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Java API提供了一个有趣的功能，它能够把线程分组。这允许我们把一个组的线程当成一个单一的单元，对组内线程对象进行访问并操作他们。例如，对于一些执行同样任务的线程，你想控制它们，不管多少线程在运行，只需要一个单一的调用，所有这些线程的运行都会被中断。
Java提供ThreadGroup类表示一组线程。线程组可以包含线程对象，也可以包含其他的线程组对象，它是一个树形结构。
下面我们学习使用ThreadGroup对象类开发一个简单的范例：创建10个线程并让它们休眠一个随机的时间（例如模拟一个查询），当其中一个线程查找成功的时候，我们将中断其它9个线程。
1. 创建一个名为Result的类
public class Result { private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } }
2. 创建一个名为SearchTask的类
import java.util.Date; import java.util.Random; import java.util.concurrent.TimeUnit; public class SearchTask implements Runnable { private Result result; public SearchTask(Result result){ this.result = result; } @Override public void run() { String name = Thread.currentThread().getName(); System.out.printf("Thread %s: Start\n", name); try { doTask(); result.setName(name); } catch (InterruptedException e) { System.out.printf("Thread %s: Interrupted\n", name); return; } System.out.printf("Thread %s: End\n", name); } private void doTask() throws InterruptedException{ Random r = new Random((new Date()).getTime()); int value = (int) (r.nextDouble()*100); System.out.printf("Thread %s: %d\n", Thread.currentThread().getName(), value); TimeUnit.SECONDS.sleep(value); } }
3. 创建主类Main
import java.util.concurrent.TimeUnit; public class Main { public static void main(String[] args) { //创建线程组 ThreadGroup threadGroup = new ThreadGroup("Searcher"); Result result = new Result(); SearchTask st = new SearchTask(result); try { for(int i=0;i<10;i++){ Thread t = new Thread(threadGroup, st); t.start(); TimeUnit.SECONDS.sleep(1); } } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } System.out.printf("Number of Threads: %d\n", threadGroup.activeCount()); System.out.printf("Information about the Thread Group\n"); threadGroup.list(); //打印线程组的信息 Thread[] threads = new Thread[threadGroup.activeCount()]; threadGroup.enumerate(threads); for(int i=0;i<threadGroup.activeCount();i++){ System.out.printf("Thread %s: %s\n", threads[i].getName(), threads[i].getState()); } //等到线程组的第一个线程运行结束 try { while(threadGroup.activeCount()>9){ TimeUnit.SECONDS.sleep(1); } } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } //中断线程组中的其它线程 threadGroup.interrupt(); } }
4. 程序运行结果如下
Thread Thread-0: Start Thread Thread-0: 75 Thread Thread-1: Start Thread Thread-1: 11 Thread Thread-2: Start Thread Thread-2: 99 Thread Thread-3: Start Thread Thread-3: 27 Thread Thread-4: Start Thread Thread-4: 18 Thread Thread-5: Start Thread Thread-5: 46 Thread Thread-6: Start Thread Thread-6: 37 Thread Thread-7: Start Thread Thread-7: 18 Thread Thread-8: Start Thread Thread-8: 6 Thread Thread-9: Start Thread Thread-9: 34 Number of Threads: 10 Information about the Thread Group java.lang.ThreadGroup[name=Searcher,maxpri=10] Thread[Thread-0,5,Searcher] Thread[Thread-1,5,Searcher] Thread[Thread-2,5,Searcher] Thread[Thread-3,5,Searcher] Thread[Thread-4,5,Searcher] Thread[Thread-5,5,Searcher] Thread[Thread-6,5,Searcher] Thread[Thread-7,5,Searcher] Thread[Thread-8,5,Searcher] Thread[Thread-9,5,Searcher] Thread Thread-0: TIMED_WAITING Thread Thread-1: TIMED_WAITING Thread Thread-2: TIMED_WAITING Thread Thread-3: TIMED_WAITING Thread Thread-4: TIMED_WAITING Thread Thread-5: TIMED_WAITING Thread Thread-6: TIMED_WAITING Thread Thread-7: TIMED_WAITING Thread Thread-8: TIMED_WAITING Thread Thread-9: TIMED_WAITING Thread Thread-1: End Thread Thread-3: Interrupted Thread Thread-2: Interrupted Thread Thread-0: Interrupted Thread Thread-4: Interrupted Thread Thread-6: Interrupted Thread Thread-5: Interrupted Thread Thread-8: Interrupted Thread Thread-7: Interrupted Thread Thread-9: Interrupted
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原文地址：http://www.cnblogs.com/gaopeng527/p/4906574.html
