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，建议在start（）调度之前设置优先级。
• 优先级的低只是意味着获得调度的概率低，并不意味优先级低就不会被调用了，这个需要看CPU的调度。
• 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;

package day03;

public class ThreadPriority {

    public static void main(String[] args) {
        //main 默认优先级 5
        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);

        //先设置优先级，再启动
        t1.start();  //Thread-0 默认优先级 5

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

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

        t4.setPriority(Thread.MAX_PRIORITY); //最大优先级
        t4.start();

        t5.setPriority(3);
        t5.start();
    }
}

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

执行结果：