Java线程优先级(Priority)

1、线程一

package com.cn.donleo.thread.priority;

import java.util.concurrent.Callable;

/**
 * @author liangd
 * date 2020-10-31 15:25
 * code
 */
public class MyThreadOne extends Thread {

    MyThreadOne(String name) {
        super(name);
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            System.out.println("第" + i + "个 MyThread： " + getName());
        }
        System.out.println("线程1的优先级：" + this.getPriority());
        MyThreadTwo myThreadTwo = new MyThreadTwo();
        myThreadTwo.start();
    }
}

2、线程二

package com.cn.donleo.thread.priority;

/**
 * @author liangd
 * date 2020-10-31 15:20
 * code
 */
public class MyThreadTwo extends Thread {
    @Override
    public void run() {
        System.out.println("线程2的优先级："+this.getPriority());
    }
}

3、线程三

package com.cn.donleo.thread.priority;


/**
 * @author liangd
 * date 2020-10-31 17:01
 * code
 */
public class MyThreadThree extends Thread {

    MyThreadThree(String name) {
        super(name);
    }

    @Override
    public void run() {
        //获取系统当前时间
        Long start = System.currentTimeMillis();
        StringBuilder stringBuilder = new StringBuilder();
        //设置时间间隔
        MyThreadFour.getTime(stringBuilder);
        Long end = System.currentTimeMillis();
        System.out.println("线程3执行时间：" + (end - start));
    }
}

4、线程四

package com.cn.donleo.thread.priority;

import java.util.Random;

/**
 * @author liangd
 * date 2020-10-31 17:17
 * code
 */
public class MyThreadFour extends Thread{

    MyThreadFour(String name) {
        super(name);
    }

    @Override
    public void run() {
        Long start = System.currentTimeMillis();
        StringBuilder stringBuilder = new StringBuilder();
        getTime(stringBuilder);
        Long end = System.currentTimeMillis();
        System.out.println("线程4执行时间：" + (end - start));
    }

    /**
     * 设置时间间隔
     * @param stringBuilder
     */
    static void getTime(StringBuilder stringBuilder) {
        for (int i = 0; i < 20; i++) {
            for (int j = 0; j < 50000; j++) {
                Random random = new Random();
                random.nextInt();
                stringBuilder.append(i);
            }
        }
    }
}

5、测试线程优先级

package com.cn.donleo.thread.priority;

/**
 * @author liangd
 * date 2020-10-31 16:49
 * code 线程优先级测试
 */
public class TestPriority {
    /**
     * 一、优先级
     *  1、设置优先级 setPriority(8)
     *  2、得到优先级 getPriority()
     *  3、线程是有优先级的,也就是线程的执行顺序
     *     MAX_PRIORITY和MIN_PRIORITY分别是最高级10和最低级1,当然还有默认级别是5;
     *
     * 二、线程优先级特性
     *  1、线程优先级的继承特性:
     *     也就是如果线程A启动线程B,那么线程A和B的优先级是一样的
     *  2、线程优先级的规则性:
     *     即线程会优先级的大小顺序执行,但是不一定是优先级较大的先执行完
     *  3、线程优先级的随机特性
     *
     * @param args
     */
    public static void main(String[] args){
        System.out.println(Thread.currentThread().getPriority());
        //设置线程优先级，范围0-10，数值越大，优先执行的概率越大
        Thread.currentThread().setPriority(8);
        //线程2放在线程1方法里面执行，只需启动线程1
//        MyThreadOne threadOne = new MyThreadOne("线程1");
        //设置线程3的优先级，执行速度概率应该比线程1和线程2更快
//        threadOne.start();


        for (int i=0;i<5 ;i++){
            MyThreadThree threadThree = new MyThreadThree("线程3");
            threadThree.setPriority(1);
            threadThree.start();
            MyThreadFour threadFour = new MyThreadFour("线程4");
            threadFour.setPriority(10);
            threadFour.start();
        }



    }
}