Java多线程 线程组原理及实例详解

public class MyThread43 implements Runnable{  public void run()  {    try    {      while (!Thread.currentThread().isInterrupted())      {        System.out.println("ThreadName = " + Thread.currentThread().getName());        Thread.sleep(3000);      }    }    catch (InterruptedException e)    {      e.printStackTrace();    }  }  public static void main(String[] args)  {    MyThread43 mt0 = new MyThread43();    MyThread43 mt1 = new MyThread43();    ThreadGroup tg = new ThreadGroup("新建线程组1");    Thread t0 = new Thread(tg, mt0);    Thread t1 = new Thread(tg, mt1);    t0.start();    t1.start();    System.out.println("活动的线程数为：" + tg.activeCount());    System.out.println("线程组的名称为：" + tg.getName());  }}

活动的线程数为：2线程组的名称为：新建线程组1ThreadName = Thread-0ThreadName = Thread-1ThreadName = Thread-0ThreadName = Thread-1ThreadName = Thread-1ThreadName = Thread-0ThreadName = Thread-1ThreadName = Thread-0・・・・・・

public class ThreadDomain49 {  public static void main(String[] args) {    System.out.println("A处线程：" + Thread.currentThread().getName() + ", 所属线程：" + Thread.currentThread().getThreadGroup().getName() +        ", 组中有线程组数量：" + Thread.currentThread().getThreadGroup().activeGroupCount());    ThreadGroup group = new ThreadGroup("新的组");    System.out.println("B处线程：" + Thread.currentThread().getName() + ", 所属线程：" + Thread.currentThread().getThreadGroup().getName() +        ", 组中有线程组数量：" + Thread.currentThread().getThreadGroup().activeGroupCount());    ThreadGroup[] tg = new ThreadGroup[Thread.currentThread().getThreadGroup().activeGroupCount()];    Thread.currentThread().getThreadGroup().enumerate(tg);    for (int i = 0; i < tg.length; i++)      System.out.println("第一个线程组名称为：" + tg[i].getName());  }}

A处线程：main, 所属线程：main, 组中有线程组数量：0B处线程：main, 所属线程：main, 组中有线程组数量：1第一个线程组名称为：新的组

public class ThreadDomain50 {  public static void main(String[] args)  {    System.out.println(Thread.currentThread().getThreadGroup().getParent().getName());    System.out.println(Thread.currentThread().getThreadGroup().getParent().getParent().getName());  }}

systemException in thread "main" java.lang.NullPointerException  at com.advance.MultiThread3.MyThread.ThreadDomain50.main(ThreadDomain50.java:14)

public class MyThread44 extends Thread{  public MyThread44(ThreadGroup tg, String name)  {    super(tg, name);  }  public void run()  {    System.out.println("ThreadName = " + Thread.currentThread().getName() +        "准备开始死循环了");    while (!this.isInterrupted()){}    System.out.println("ThreadName = " + Thread.currentThread().getName() +        "结束了");  }  public static void main(String[] args) throws InterruptedException {    ThreadGroup tg = new ThreadGroup("我的线程组");    MyThread44 mt = null;    for (int i = 0; i < 3; i++)    {      mt = new MyThread44(tg, "线程" + i);      mt.start();    }    Thread.sleep(5000);    tg.interrupt();    System.out.println("调用了interrupt()方法");  }}

ThreadName = 线程0准备开始死循环了ThreadName = 线程1准备开始死循环了ThreadName = 线程2准备开始死循环了调用了interrupt()方法ThreadName = 线程0结束了ThreadName = 线程2结束了ThreadName = 线程1结束了