Thread和ThreadGroup

Thread和ThreadGroup

学习了：https://www.cnblogs.com/yiwangzhibujian/p/6212104.html  这个里面有Thread的基本内容；

http://blog.csdn.net/a352193394/article/details/39323427 这个讲解了ThreadGroup

https://www.cnblogs.com/yy2011/archive/2011/05/05/2037564.html 这个比较了ThreadGroup与Executor

Thread比如属于一个ThreadGroup，

源码：

        Thread parent = currentThread();
        SecurityManager security = System.getSecurityManager();
        if (g == null) { // 这个就是ThreadGroup
            /* Determine if it's an applet or not */

            /* If there is a security manager, ask the security manager
               what to do. */
            if (security != null) {
                g = security.getThreadGroup();
            }

            /* If the security doesn't have a strong opinion of the matter
               use the parent thread group. */
            if (g == null) {
                g = parent.getThreadGroup();
            }
        }

Thread.setUncaughtExceptionHandler的意义在于不能修改原线程的情况下，为其增加一个错误处理器。

package com.stono.thread2;

import java.lang.Thread.UncaughtExceptionHandler;

// UnCaughtException意义在于不能对原线程修改的情况下，为其增加一个错误处理器。
public class ThreadUncaughtException {
    public static void main(String[] args) {
        Thread t1 = new Thread(new Runnable() {
            public void run() {
                int a = 1/0;
            }
        });
        t1.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
            @Override
            public void uncaughtException(Thread t, Throwable e) {
                System.out.println("线程："+t.getName()+"出现异常，异常信息："+e);
                e.printStackTrace();
            }
        });
        t1.start();
    }
}

ThreadGroup.enumerate(list)方法把ThreadGroup中的线程拷贝到新的List中；

在ThreadGroup讲解过程中，一个runnable对象构建了多个线程，这个需要注意一下，TODO