JAVA多线程--Thread(4)

JAVA多线程--Thread(4) 线程状态

Thread.state

New尚未启动的线程处于此状态Runnable在java虚拟机中执行的线程处于此状态Blocked被阻塞等待监视器锁定的线程处于此状态Waiting正在等待另一个线程执行特定动作的线程处于此状态Time_Waiting正在等待另一个线程执行动作达到指定等待时间的线程处于此状态Terminated已退出的线程处于此状态

package Thread;


public class TestState {

	public static void main(String[] args) throws InterruptedException {
		Thread thread = new Thread(()->{
			for(int i = 0; i < 5; i++) {
				try {
					Thread.sleep(1000);
				} catch (InterruptedException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			System.out.println("");
		});
		
		
		Thread.State state = thread.getState();
		System.out.println(state);
		
		
		thread.start();//启动线程
		state = thread.getState();
		System.out.println(state);//run
		
		
		while(state != Thread.State.TERMINATED) {
			Thread.sleep(100);
			
			state = thread.getState();
			System.out.println(state);
		}
		
	}
}

输出：

NEW
RUNNABLE
TIMED_WAITING
TIMED_WAITING

·········

TIMED_WAITING

TERMINATED

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线程优先级

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; 使用以下方式改变或获取优先级：

getPriority().setPriority(int xxx) 优先级的设定建议在start调度前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，这都是看CPU的调度

package Thread;

public class TestPriority {

	public static void main(String[] args) {
		
		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);
		
		
		t1.start();
		
		t2.setPriority(1);
		t2.start();
		
		t3.setPriority(Thread.MAX_PRIORITY);
		t3.start();
		
		t4.setPriority(8);
		t4.start();
		
		t5.setPriority(Thread.MAX_PRIORITY);
		t5.start();
		
	}
	
}

class MyPriority implements Runnable{

	@Override
	public void run() {
		// TODO Auto-generated method stub
		System.out.println(Thread.currentThread().getName()+
				"-->"+Thread.currentThread().getPriority());
	}
	
}

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守护线程

线程分为用户线程和守护线程虚拟机必须确保用户线程执行完毕虚拟机不用等待守护线程执行完毕如 后台记录 *** 作日志、监控内存、垃圾回收等待