从头认识java-18.2 主要的线程机制(7)join
2017-08-10 11:48 tlnshuju 阅读(225) 评论(0) 编辑 收藏 举报这一章节我们来讨论一下join。
1.什么是join?
阻塞当前线程,让.join的线程先做完。然后再继续当前线程
以下是api的解释:
A.join,在API中的解释是,阻塞当前线程B,直到A运行完毕并死掉,再运行B。
2.样例:
package com.ray.ch17; public class Test { public static void main(String[] args) throws InterruptedException { System.out.println(Thread.currentThread().getName() + " start"); SleepThread sleepThread = new SleepThread("sleep"); Thread.sleep(2000); JoinThread joinThread = new JoinThread(sleepThread, "join"); // joinThread.join(); System.out.println(Thread.currentThread().getName() + " end"); } } class SleepThread extends Thread { public SleepThread(String name) { super(name); start(); } @Override public void run() { try { for (int i = 0; i < 5; i++) { System.out.println(getName() + " SleepThread"); Thread.sleep(1000); } } catch (InterruptedException e) { e.printStackTrace(); } } } class JoinThread extends Thread { private SleepThread sleepThread; public JoinThread(SleepThread sleepThread, String name) { super(name); this.sleepThread = sleepThread; start(); } @Override public void run() { try { System.out.println(getName() + " join start"); sleepThread.join(); System.out.println(getName() + " join end"); } catch (InterruptedException e) { e.printStackTrace(); } } }
输出:
main start
sleep SleepThread
sleep SleepThread
sleep SleepThread
main end
join join start
sleep SleepThread
sleep SleepThread
join join end
package com.ray.ch17; public class Test { public static void main(String[] args) throws InterruptedException { System.out.println(Thread.currentThread().getName() + " start"); SleepThread sleepThread = new SleepThread("sleep"); Thread.sleep(2000); JoinThread joinThread = new JoinThread(sleepThread, "join"); joinThread.join(); System.out.println(Thread.currentThread().getName() + " end"); } } class SleepThread extends Thread { public SleepThread(String name) { super(name); start(); } @Override public void run() { try { for (int i = 0; i < 5; i++) { System.out.println(getName() + " SleepThread"); Thread.sleep(1000); } } catch (InterruptedException e) { e.printStackTrace(); } } } class JoinThread extends Thread { private SleepThread sleepThread; public JoinThread(SleepThread sleepThread, String name) { super(name); this.sleepThread = sleepThread; start(); } @Override public void run() { try { System.out.println(getName() + " join start"); sleepThread.join(); System.out.println(getName() + " join end"); } catch (InterruptedException e) { e.printStackTrace(); } } }
输出:
main start
sleep SleepThread
sleep SleepThread
sleep SleepThread
join join start
sleep SleepThread
sleep SleepThread
join join end
main end
上面两个代码的不同主要是体如今joinThread.join();是否被凝视。
对照上面的两个代码的输出,主要不同在于main end 的位置。当joinThread.join();的时候,因为须要先阻塞main方法的线程,先完毕joinThread所在线程,因此main end的位置会出现上面的变化。
还有一方面。我们从sleep和join两个线程输出的文字的位置也能够推导出上面的结论。
总结:这一章节我们简介了一下join。
这一章节就到这里,谢谢。
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