java多线程——闭锁和栅栏
题目描述 -闭锁
题目
有3个线程，线程A和线程B并行执行，线程C需要和线程A和B执行完成后才能执行，使用闭锁
CountDownLatch实现
解题思路：
创建一个类 ：Abc Test
CountDownLatch初始化值为2
新增 A B线程，在线程里执行逻辑后，计算-1
countDownLatch.countDown() 新增C线程,等待A,B线程来完成
countDownLatch.await();
执行相关的逻辑
代码详解：
AbcTest：
package cn.xiaoxuzhu.daily;
import java.util.concurrent.CountDownLatch;
public class AbcTest {
public static void main(String[] args) {
CountDownLatch countDownLatch =new CountDownLatch(2);
//线程A
new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(2000);
}catch (InterruptedException e){
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+":"+"线程A执行结束");
countDownLatch.countDown();
}
},"线程A").start();
//线程B
new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(1000);
}catch (InterruptedException e){
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+":"+"线程B执行结束");
countDownLatch.countDown();
}
},"线程B").start();
new Thread(new Runnable() {
@Override
public void run() {
try {
countDownLatch.await();
}catch (InterruptedException e){
e.printStackTrace();
}
System.out.println(Thread.currentThread().getName()+":"+"线程C执行结束");
countDownLatch.countDown();
}
},"线程C").start();
}
} 
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