线程可以通过设置优先级来控制获得CPU的概率，注意这里只是概率，如果低优先级的线程很早到达，且能被分到CPU那么此时低优先的线程会比高优先级但后到来的线程更早运行
可以通过getPriority 与 setPriority 来获取和设置线程的优先级
/*** The minimum priority that a thread can have.*/public static final int MIN_PRIORITY = 1;/*** The default priority that is assigned to a thread.*/public static final int NORM_PRIORITY = 5;/*** The maximum priority that a thread can have.*/public static final int MAX_PRIORITY = 10;
由官方文档不难看出，线程优先级的设置只能在[1, 10]之间，超过会抛出异常
public class ThreadPriority {public static void main(String[] args) {System.out.println(Thread.currentThread().getName()+"-->"+Thread.currentThread().getPriority());MyThread myThread = new MyThread();Thread thread1 = new Thread(myThread);Thread thread2 = new Thread(myThread);Thread thread3 = new Thread(myThread);Thread thread4 = new Thread(myThread);// 先设置优先级，再启动thread1.start();thread2.setPriority(1);thread2.start();thread3.setPriority(4);thread3.start();thread4.setPriority(Thread.MAX_PRIORITY);thread4.start();}
}
通过上面的程序我们可能会观测到线程优先级带来的变化，但是一定可以得到的是，线程的默认优先级是5，也就是NORM_PRIORITY