多线程编程

code/Java/java-concurrency/src/main/java/com/heibaiying/countDown/J2_CountDown.java

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+package com.heibaiying.countDown;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class J2_CountDown {
+
+	private static int number = 100;
+	private static CountDownLatch latch = new CountDownLatch(number);
+	private static AtomicInteger integer = new AtomicInteger(0);
+
+
+	static class IncreaseTask implements Runnable {
+		@Override
+		public void run() {
+			try {
+				// 假设这是一个耗时的任务
+				Thread.sleep(3000);
+				integer.incrementAndGet();
+				// 计数减一
+				latch.countDown();
+			} catch (InterruptedException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+
+	public static void main(String[] args) throws InterruptedException {
+		IncreaseTask task = new IncreaseTask();
+		ExecutorService executorService = Executors.newFixedThreadPool(100);
+		for (int i = 0; i < number; i++) {
+			executorService.submit(task);
+		}
+		latch.await();
+		// 会等待所有任务执行完成再输出
+		System.out.println("integer：" + integer);
+		executorService.shutdown();
+	}
+}

code/Java/java-concurrency/src/main/java/com/heibaiying/countDown/j1_Normal.java

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+package com.heibaiying.countDown;
+
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class j1_Normal {
+
+	private static AtomicInteger integer = new AtomicInteger(0);
+
+	static class IncreaseTask implements Runnable {
+		@Override
+		public void run() {
+			try {
+				// 假设这是一个耗时的任务
+				Thread.sleep(3000);
+				integer.incrementAndGet();
+			} catch (InterruptedException e) {
+				e.printStackTrace();
+			}
+		}
+	}
+
+	public static void main(String[] args) {
+		IncreaseTask task = new IncreaseTask();
+		ExecutorService executorService = Executors.newFixedThreadPool(100);
+		for (int i = 0; i < 100; i++) {
+			executorService.submit(task);
+		}
+		// 不会等待所有任务完成就输出，此时通常为0
+		System.out.println("integer：" + integer);
+		executorService.shutdown();
+	}
+}