《Java多线程编程核心技术》读后感（十六）

 

 

线程组

线程组的作用是，可以批量的管理线程或线程组对象，有效地对线程或线程组对象进行组织

线程对象关联线程组：1级关联

package Seven;

public class ThreadA  extends Thread {

    @Override
    public void run() {
        try {
            while (!Thread.currentThread().isInterrupted()) {
                System.out.println("ThreadName=" + Thread.currentThread().getName());
                Thread.sleep(3000);
            }
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

package Seven;

public class ThreadB extends Thread {

    @Override
    public void run() {
        try {
            while (!Thread.currentThread().isInterrupted()) {
                System.out.println("ThreadName=" + Thread.currentThread().getName());
                Thread.sleep(3000);
            }
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

package Seven;

public class Run {
    public static void main(String[] args) {
        ThreadA aRunnable = new ThreadA();
        ThreadB bRunnable = new ThreadB();

        ThreadGroup group = new ThreadGroup("高洪岩的线程组");

        Thread aThread = new Thread(group, aRunnable);
        Thread bThread = new Thread(group, bRunnable);
        aThread.start();
        bThread.start();

        System.out.println("活动的线程数为：" + group.activeCount());
        System.out.println("线程组的名称为：" + group.getName());

    }
}

 线程对象关联线程组：多级关联

package Seven;

public class Run {
    public static void main(String[] args) {

        // 在main组中添加一个线程组A，然后在这个A组中添加线程对象Z
        // 方法activeGroupCount()和activeCount()的值不是固定的
        // 是系统中环境的一个快照
        ThreadGroup mainGroup = Thread.currentThread().getThreadGroup();
        ThreadGroup group = new ThreadGroup(mainGroup, "A");
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                try {
                    System.out.println("runMethod!");
                    Thread.sleep(10000);// 线程必须在运行状态才可以受组管理
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        };

        Thread newThread = new Thread(group, runnable);
        newThread.setName("Z");
        newThread.start();// 线程必须启动然后才归到组A中
        // ///
        ThreadGroup[] listGroup = new ThreadGroup[Thread.currentThread()
                .getThreadGroup().activeGroupCount()];
        Thread.currentThread().getThreadGroup().enumerate(listGroup);
        System.out.println("main线程中有多少个子线程组：" + listGroup.length + " 名字为："
                + listGroup[0].getName());
        Thread[] listThread = new Thread[listGroup[0].activeCount()];
        listGroup[0].enumerate(listThread);
        System.out.println(listThread[0].getName());

    }
}

线程组自动归属特性

自动归属就是自动归到当前线程组中

package Seven;

public class Run {
    public static void main(String[] args) {
        System.out.println("A处线程："+Thread.currentThread().getName()
                + " 所属的线程组名为："
                + Thread.currentThread().getThreadGroup().getName()+ " "
                + " 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()
                + " 所属的线程组名为："
                + Thread.currentThread().getThreadGroup().getName()+ " "
                +" 中有线程组数量："+Thread.currentThread().getThreadGroup().activeGroupCount());
        ThreadGroup[] threadGroup=new ThreadGroup[Thread.currentThread().getThreadGroup().activeGroupCount()];
        Thread.currentThread().getThreadGroup().enumerate(threadGroup);
        for (int i = 0; i < threadGroup.length; i++) {
            System.out.println("第一个线程组名称为："+threadGroup[i].getName());
        }
    }
}

未完，待续。。。