• CountDownLatch：用于監聽某些初始化操作，并且線程進行阻塞，等初始化執行完畢后，通知主線程繼續工作執行

package com.example.core.juc;import java.util.concurrent.CountDownLatch;public class UseCountDownLatch {public static void main(String[] args) {CountDownLatch countDownLatch = new CountDownLatch(2);//需要兩次喚醒Thread t1 = new Thread(new Runnable() {@Overridepublic void run() {System.out.println("進入t1線程");try{Thread.sleep(3000);//做一些初始化準備}catch(InterruptedException e){e.printStackTrace();}System.out.println("t1線程初始化完畢，通知t3線程繼續操作");countDownLatch.countDown();//通知t3}},"t1");Thread t2 = new Thread(new Runnable() {@Overridepublic void run() {System.out.println("進入t2線程");try{Thread.sleep(3000);//做一些初始化準備}catch(InterruptedException e){e.printStackTrace();}System.out.println("t2線程初始化完畢，通知t3線程繼續操作");countDownLatch.countDown();//通知t3}},"t2");Thread t3 = new Thread(new Runnable() {@Overridepublic void run() {System.out.println("進入t3線程,進入等待階段");try{countDownLatch.await();//等待階段，需要喚醒}catch(InterruptedException e){e.printStackTrace();}System.out.println("t3線程 進行后續的操作");}},"t3");t1.start();t2.start();t3.start();}
}
/*
進入t1線程
進入t2線程
進入t3線程,進入等待階段
t1線程初始化完畢，通知t3線程繼續操作
t2線程初始化完畢，通知t3線程繼續操作
t3線程 進行后續的操作
*/

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