45--多线程(四)

线程中常用的方法(续)

判断线程是否启动:isAlive()
实例:

package com.qwy5;

class MyThread extends Thread {
    
    
	@Override
	public void run() {
    
    
		for (int i = 0; i <= 5; i++) {
    
    
			System.out.println(Thread.currentThread().getName() + "--" + i);
		}
	}
}
public class TestThreadIsAlive {
    
    
	public static void main(String[] args) {
    
    
		MyThread t1 = new MyThread();
		System.out.println("线程开始执行之前:"+t1.isAlive());
		t1.start();
		System.out.println("线程开始执行之后:"+t1.isAlive());
		for (int i = 0; i <= 5; i++) {
    
    
			System.out.println(Thread.currentThread().getName() + "--" + i);
		}
		System.out.println("线程执行之后:"+t1.isAlive());//后面输出的结果不确定
	}
}

可能执行结果:
线程开始执行之前:false
线程开始执行之后:true
main–0
main–1
main–2
main–3
Thread-0–0
main–4
main–5
Thread-0–1
Thread-0–2
线程执行之后:true
Thread-0–3
Thread-0–4
Thread-0–5

另外的可能的一种结果:

线程开始执行之前:false
线程开始执行之后:true
main–0
main–1
main–2
Thread-0–0
Thread-0–1
Thread-0–2
Thread-0–3
Thread-0–4
Thread-0–5
main–3
main–4
main–5
线程执行之后:false

以上输出结果是不确定的,有可能到最后时,线程已经不存在了,也有可能继续存在,这要看那个线程先执行完了。

线程的休眠:sleep(long millitime)
让当前线程“睡眠”指定的millitime毫秒。在指定的millitime毫秒时间内,当前线程是阻塞状态。
实例:

package com.qwy6;

class MyThread extends Thread {
    
    
	@Override
	public void run() {
    
    
		for (int i = 0; i <=10; i++) {
    
    
			try {
    
    
				//线程休眠1秒
				Thread.sleep(1000);
			} catch (InterruptedException e) {
    
    
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			System.out.println(Thread.currentThread().getName() + "--" + i);
		}
	}
}
public class TestThreadSleep {
    
    
	public static void main(String[] args) {
    
    
		MyThread t1 = new MyThread();
		t1.start();
	}
}

运行结果:
Thread-0–0
Thread-0–1
Thread-0–2
Thread-0–3
Thread-0–4
Thread-0–5
Thread-0–6
Thread-0–7
Thread-0–8
Thread-0–9
Thread-0–10

程序运行时,每次输出都会间隔1000ms,达到了延迟操作的速度。

未完待续
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转载自blog.csdn.net/qwy715229258163/article/details/114858134