Java基础__Java中多线程那些事

Posted 2020-11-12 1138720556gary

（未完）

 

一、测试

查看线程的运行状态

package Cynical_Gary;

public class ThreadState implements Runnable{
    public synchronized void waitForASecond() throws InterruptedException{
        //使当前线程等待0.5秒或其它线程调用notify()或notifyAll()方法
        wait(500);
    }
    
    public synchronized void waitForYears() throws InterruptedException{
        //使当前现场永久等待，直到其他线程调用notify()或notifyAll()方法
        wait();
    }
    
    public synchronized void notifyNow() throws InterruptedException{
        //唤醒由调用wait()方法进入等待状态的线程
        notify();
    }
    
    @Override
    public void run() {
        // TODO Auto-generated method stub
        try{
            //在新线程中运行waitForASecond()方法
            waitForASecond();
            //在新线程中运行waitForYears();方法
            waitForYears();
        }catch(InterruptedException e){
            e.printStackTrace();
        }
    }

}

ThreadState类

package Cynical_Gary;

public class Gary_Text {

    public static void main(String[] args) throws InterruptedException{
        //创建State对象
        ThreadState state = new ThreadState();
        //利用State对象创建Thread对象
        Thread thread = new Thread(state);
        //输出线程状态
        System.out.println("新建线程:"+thread.getState());
        //启动新线程
        thread.start();
        //输出线程状态
        System.out.println("启动线程:"+thread.getState());
        //当前线程休眠0.1秒，使新线程运行waitForASecond()方法
        Thread.sleep(100);
        //输出线程状态
        System.out.println("计时等待:"+thread.getState());
        //当前线程休眠1秒，使新线程运行waitForYears()方法
        Thread.sleep(1000);
        //输出线程状态
        System.out.println("等待线程:"+thread.getState());
        state.notifyNow();
        System.out.println("唤醒线程:"+thread.getState());
        //当前线程休眠1秒，使新线程结束
        Thread.sleep(1000);
        //输出线程状态
        System.out.println("终止线程:"+thread.getState());
    }

}


/*
 输出：
 新建线程:NEW
启动线程:RUNNABLE
计时等待:TIMED_WAITING
等待线程:WAITING
唤醒线程:RUNNABLE
终止线程:TERMINATED
 */

Text类()测试

 

package Cynical_Gary;

import java.util.ArrayList;
import java.util.List;

public class Gary_Text {
    //获得根线程组
    private static ThreadGroup getRootThreadGroup(){
        //获得当前线程组
        ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();
        while(true){
            //getParent()方法的返回值非空则不是根线程组
            if(rootGroup.getParent()!=null){
            //获得父线程组
            rootGroup = rootGroup.getParent();    
            }else{
            //如果达到根线程组则退出循环
                break;
            }
        }
        //返回根线程组
        return rootGroup;
    }
    
    //获得给定线程组中所有线程名
    public static List<String> getThreads(ThreadGroup group){
        //创建保存线程名的列表
        List<String> threadList = new ArrayList<String>();
        //根据活动线程数穿件线程数组
        Thread[] threads = new Thread[group.activeCount()];
        //复制线程到线程数组
        int count = group.enumerate(threads,false);
        //遍历线程数组将线程名及所在组保存到列表中
        for(int i=0;i<count;i++){
            threadList.add(group.getName()+"线程组："+threads[i].getName());
        }
        //返回列表
        return threadList;
    }
    
    //获得给定线程组中子线程
    public static List<String> getThreadGroups(ThreadGroup group){
        //创建保存线程名的列表
        List<String> threadList = getThreads(group);
        //创建线程组数组
        ThreadGroup[] groups = new ThreadGroup[group.activeGroupCount()];
        //复制子线程数组到线程组数据
        int count = group.enumerate(groups,false);
        //遍历所有子线程数组
        for(int i=0;i<count;i++){
            //利用getThreads()方法获得线程名列表
            threadList.addAll(getThreads(groups[i]));
        }
        //返回所有线程名
        return threadList;
    }
    
    public static void main(String[] args){
        for(String string:getThreadGroups(getRootThreadGroup())){
            //遍历输出列表中的字符串
            System.out.println(string);
        }
    }

}


/*
 输出：
system线程组：Reference Handler
system线程组：Finalizer
system线程组：Signal Dispatcher
system线程组：Attach Listener
main线程组：main
*/

查看JVM中的线程名