实例讲解java怎样利用CountDownLatch实现并行计算

import java.util.concurrent.CountDownLatch;

/**
 * @Author pipi
 * @Date 2018/10/15 13:56
 **/
public class ParallelComputing {
  private int[] nums;
  private String[] info;
  private CountDownLatch countDownLatch;

  public ParallelComputing(String[] info) {
    this.info = info;
    int size = info.length;
    nums = new int[size];
    this.countDownLatch = new CountDownLatch(size);
  }

  public void calc(String line, int index) throws InterruptedException {
    String[] numbers = line.split(",");
    int total = 0;
    for (String num : numbers) {
      total += Integer.parseInt(num);
    }
    Thread.sleep(5000);
    nums[index] = total;
    countDownLatch.countDown();
    System.out.println(Thread.currentThread().getName() + "执行计算任务..." + line + ",结果为：" + total);
  }

  public void sum() {
    System.out.println("汇总线程开始执行...");
    int total = 0;
    for (int i : nums) {
      total += i;
    }
    System.out.println("汇总线程结束执行...结果为：" + total);
  }

  public void calcSum() throws InterruptedException {
    int size = info.length;
    for (int i = 0; i < size; i++) {
      final int j = i;
      new Thread(() -> {
        try {
          calc(info[j], j);
        } catch (InterruptedException e) {
          e.printStackTrace();
        }
      }).start();
    }
    countDownLatch.await();
    sum();
  }

  public static void main(String[] args) throws InterruptedException {
    long start = System.currentTimeMillis();
    String[] info = {
        "2,22",
        "3,33",
        "232,32,76,84",
        "99,45,1"
    };
    ParallelComputing parallelComputing = new ParallelComputing(info);
    parallelComputing.calcSum();
    long end = System.currentTimeMillis();
    System.out.println(end - start);
  }
}