Java多線程之CountDownLatch用法

---

本文目錄：

CountDownLatch基本概念

CountDownLatch案例：6個同學陸續離開教室后班長才可以關門

CountDownLatch案例：秦滅6國，一統華夏

---

1. CountDownLatch基本概念

1. 讓一些線程阻塞直到另一些線程完成一系列操作后才被喚醒。

2. CountDownLatch主要有兩個方法，當一個或多個線程調用await方法時，這些線程會阻塞。其它線程調用countDown方法會將計數器減1(調用countDown方法的線程不會阻塞)，當計數器的值變為0時，因await方法阻塞的線程會被喚醒，繼續執行。

---

2. CountDownLatch案例：6個同學陸續離開教室后班長才可以關門

實現：

public class CountDownLatchDemo {public static void main(String[] args) throws InterruptedException {CountDownLatch countDownLatch = new CountDownLatch(6);for (int i = 1; i <=6 ; i++) {new Thread(() -> {System.out.println(Thread.currentThread().getName()+"\t 同學離開教室");countDownLatch.countDown();},String.valueOf(i)).start();}countDownLatch.await();System.out.println(Thread.currentThread().getName()+"\t 班長關門走人");} }

---

編譯結果

---

3. CountDownLatch案例：秦滅6國，一統華夏

六國我們用枚舉模擬，具體代碼如下：

public enum CountryEnums {ONE(1,"韓"),TWO(2,"魏"),THREE(3,"趙"),FOUR(4,"齊"),FIVE(5,"楚"),SIX(6,"燕");private Integer retCode;private String retMessage;CountryEnums(Integer retCode, String retMessage) {this.retCode = retCode;this.retMessage = retMessage;}public Integer getRetCode() {return retCode;}public void setRetCode(Integer retCode) {this.retCode = retCode;}public String getRetMessage() {return retMessage;}public void setRetMessage(String retMessage) {this.retMessage = retMessage;}public static CountryEnums forEachCountryEnums(Integer index){for (CountryEnums element: values()) {if (element.getRetCode() == index){return element;}}return null;} }

---

主體代碼：

public class CountDownLatchDemo {public static void main(String[] args) throws InterruptedException {CountDownLatch countDownLatch = new CountDownLatch(6);for (int i = 1; i <=6 ; i++) {new Thread(() -> {System.out.println(Thread.currentThread().getName()+"\t 國被滅亡");countDownLatch.countDown();},CountryEnums.forEachCountryEnums(i).getRetMessage()).start();}countDownLatch.await();System.out.println(Thread.currentThread().getName()+"\t 秦，統一華夏");System.out.println("------------------");//枚舉測試代碼System.out.println(CountryEnums.ONE);System.out.println(CountryEnums.ONE.getRetCode());System.out.println(CountryEnums.ONE.getRetMessage());}

---

編譯結果：

總結

以上是生活随笔為你收集整理的Java多线程之CountDownLatch用法的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。