线程简介（一）

/**
 * @Author YangHe
 * @Date 2020/4/7 11:52
 */
public class ThreadTest extends Thread {
    private int j;
    public ThreadTest(String name){
            super(name);
    }
    public ThreadTest(ThreadGroup threadGroup,String name){
        super(threadGroup,name);
    }
    @Override
    public void run() {

            for(;j<100;j++){
                System.out.println(getName()+"       "+j +" "+getThreadGroup().activeCount()); //显示该线程组活跃的线程数
                if(j==50){
                    Thread.yield();       //当变量值为50 放弃当前资源  进入就绪状态
                  /*  try {
                        Thread.sleep(1000); //当变量值为50 睡眠一秒 进入阻塞状态
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }*/
                }
            }
    }

    public static void main(String[] args) {
        ThreadTest t=new ThreadTest("6666666666");
        t.setDaemon(true);//该线程设置为后台线程，所有线程结束该线程结束
        t.start();
        for(int i=0;i<100;i++){
            System.out.println(Thread.currentThread().getName()+"  "+i);
            if(i==20){
                ThreadGroup threadGroup=new ThreadGroup("测试");//新建线程组 ,设置线程组名称
                ThreadTest t1=new ThreadTest(threadGroup,"杨贺");
                ThreadTest t2=new ThreadTest("李小艺");
                t1.start();
                t2.start();
            }
        }
    }
}

/**
 * @Author YangHe
 * @Date 2020/4/7 11:52
 */
public class RunnableTest implements Runnable{
    private int j;
    @Override
    public void run() {
        for(;j<100;j++){
            System.out.println(Thread.currentThread().getName()+"       "+j);
        }
    }
    public static void main(String[] args) {
        for(int i=0;i<100;i++){
            System.out.println(Thread.currentThread().getName()+"  "+i);
            if(i==20){
                RunnableTest r=new RunnableTest();
                new Thread(r,"杨贺").start();
                new Thread(r,"李小艺").start();
            }
        }
    }
}

import java.util.concurrent.Callable;
import java.util.concurrent.FutureTask;

/**
 * @Author YangHe
 * @Date 2020/4/7 15:47
 */
public class CallableTest implements Callable<Integer> {
    @Override
    public Integer call() throws Exception {
        int i=0;
        for(;i<100;i++){
            System.out.println(Thread.currentThread().getName()+"  "+i);
        }
        return i;
    }

    public static void main(String[] args) throws InterruptedException {
        CallableTest callableTest=new CallableTest();
        FutureTask<Integer> task=new FutureTask<Integer>(callableTest);
        for(int i=0;i<100;i++){
            System.out.println(Thread.currentThread().getName()+"循环变量的值为 "+i);
            if(i==20){
                Thread t1=new Thread(task,"李小艺");
                t1.start();
                t1.join(); //等待该线程执行完成，主线程再执行
            }
        }
        try{
            System.out.println("子线程的返回值为 "+task.get());
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}