zoukankan      html  css  js  c++  java
  • Java多线程(十一):线程组

    线程组

    线程组可以批量管理线程和线程组对象。

    一级关联

    例子如下,建立一级关联。

    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());
        }
    }
    

    输出结果如下

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

    每隔三秒输出两个线程名称,符合预期。

    线程组自动归组属性

    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());
        }
    }
    

    输出结果如下

    A处线程:main, 所属线程:main, 组中有线程组数量:0
    B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
    

    没有指定线程组,则归属到当前线程所属的组。

    根线程组

    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());
        }
    
    
    }
    

    运行结果

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

    当前线程的线程组的父线程组是系统线程组;系统线程组的父线程组不存在;系统线程组就是根线程组。

    批量停止组内线程
    请看示例

    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");
        }
    }
    

    输出结果如下

    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
    

    可以看到,ThreadGroup的interrupt方法批量中断线程组的线程。

  • 相关阅读:
    高斯消元学习
    HDU 4596 Yet another end of the world(解一阶不定方程)
    Codeforces Round #318 div2
    HDU 4463 Outlets(一条边固定的最小生成树)
    HDU 4458 Shoot the Airplane(计算几何 判断点是否在n边形内)
    HDU 4112 Break the Chocolate(简单的数学推导)
    HDU 4111 Alice and Bob (博弈)
    POJ 2481 Cows(线段树单点更新)
    HDU 4288 Coder(STL水过)
    zoj 2563 Long Dominoes
  • 原文地址:https://www.cnblogs.com/Java-Starter/p/11358207.html
Copyright © 2011-2022 走看看