线程的优先级

java提供一个线程调度器来监控程序中启动后进入就绪状态的所有线程，线程调度器按照优先级决定应该调度哪个线程来执行

线程的优先级用数字表示，范围从1~10

• Thread.MIN_PRIORITY=1;
• Thread.MAX_PRIORITY=10;
• Thread.NORM_PRIORITY=5;

可以通过getPriority() .setPriority(int xxx)改变或获取优先级

package com.yuanyu.thread;

//测试线程的优先级
public class TestPriority{
    public static void main(String[] args) {
        //主线程默认优先级
        System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());

        MyPriority myPriority = new MyPriority();
        Thread t1 =new Thread(myPriority);
        Thread t2 =new Thread(myPriority);
        Thread t3 =new Thread(myPriority);
        Thread t4 =new Thread(myPriority);
        Thread t5 =new Thread(myPriority);
        Thread t6 =new Thread(myPriority);

        //先设置优先级再启动
        t1.start();

        t2.setPriority(1);
        t2.start();

        t3.setPriority(4);
        t3.start();

        t4.setPriority(Thread.MAX_PRIORITY);
        t4.start();

        t5.setPriority(-1);
        t5.start();

        t6.setPriority(11);
        t6.start();

    }
}

class MyPriority implements Runnable{

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName()+"--->"+Thread.currentThread().getPriority());
    }
}

程序运行结果：

注意：

• 线程的默认优先级都是5
• 线程优先级高的不一定先执行， 优先级低只是意味着获得调度的概率低，并不是优先级低就不会被调用了，都是看CPU的调度
• 优先级的设定建议在start()调度前