学习过程观看视频：[狂神说Java]
https://www.bilibili.com/video/BV1B7411L7tE?p=13
欢迎大家支持噢，很良心的老师了！
1、java代码：
package com.add;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
/**
* Created by zjl
* 2020/11/24
**/
public class CyclicBarrierDemo {
public static void main(String[] args) {
/*
* 集齐7颗龙珠召唤神龙
* */
//召唤龙珠的线程
CyclicBarrier cyclicBarrier = new CyclicBarrier(7, () -> {
System.out.println("已经 集齐7颗龙珠，召唤神龙！");
});
for (int i = 1; i <= 7; i++) {
//lambda表达式中无法直接拿到temp，所以用final修饰的中间变量接收一下
final int temp = i;
new Thread(()->{
System.out.println("收集到第"+ temp + "颗龙珠");
try {
cyclicBarrier.await(); //等待
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}).start();
}
}
}
运行结果：
/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/bin/java "-javaagent:/Users/zhangjianlong/Library/Application Support/JetBrains/Toolbox/apps/IDEA-U/ch-0/193.5662.53/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=65480:/Users/zhangjianlong/Library/Application Support/JetBrains/Toolbox/apps/IDEA-U/ch-0/193.5662.53/IntelliJ IDEA.app/Contents/bin" -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_231.jdk/Contents/Home/lib/tools.jar:/Users/zhangjianlong/testCode/JUC-study/target/classes:/Users/zhangjianlong/apache-maven-3.6.3/repository/org/projectlombok/lombok/1.18.8/lombok-1.18.8.jar com.add.CyclicBarrierDemo
收集到第1颗龙珠
收集到第3颗龙珠
收集到第2颗龙珠
收集到第5颗龙珠
收集到第4颗龙珠
收集到第6颗龙珠
收集到第7颗龙珠
已经 集齐7颗龙珠，召唤神龙！
Process finished with exit code 0
2、当我们创建CyclicBarrier时，参数改为8的时候，永远也无法集齐7颗龙珠。
java代码：
package com.add;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
/**
* Created by zjl
* 2020/11/24
**/
public class CyclicBarrierDemo {
public static void main(String[] args) {
/*
* 集齐7颗龙珠召唤神龙
* */
//召唤龙珠的线程
CyclicBarrier cyclicBarrier = new CyclicBarrier(8, () -> {
System.out.println("已经 集齐7颗龙珠，召唤神龙！");
});
for (int i = 1; i <= 7; i++) {
//lambda表达式中无法直接拿到temp，所以用final修饰的中间变量接收一下
final int temp = i;
new Thread(()->{
System.out.println("收集到第"+ temp + "颗龙珠");
try {
cyclicBarrier.await(); //等待
} catch (InterruptedException e) {
e.printStackTrace();
} catch (BrokenBarrierException e) {
e.printStackTrace();
}
}).start();
}
}
}
运行结果：
