package com.basic; import java.io.IOException; import java.util.Arrays; import java.util.Random; import java.util.concurrent.ForkJoinPool; import java.util.concurrent.RecursiveAction; import java.util.concurrent.RecursiveTask; /** * @program JavaBooks * @description: 第六种，ForkJoinPool * @author: mf * @create: 2020/01/01 15:12 */ public class T29 { private static int[] nums = new int[1000000]; private static final int MAX_NUM = 50000; private static Random r = new Random(); static { for (int i = 0; i < nums.length; i++) { nums[i] = r.nextInt(100); } System.out.println(Arrays.stream(nums).sum()); } /** * 没有返回值 */ // private static class AddTask extends RecursiveAction { // // int start, end; // // public AddTask(int start, int end) { // this.start = start; // this.end = end; // } // // @Override // protected void compute() { // if (end - start <= MAX_NUM) { // long sum = 0L; // for (int i = start; i < end; i++) { // sum += nums[i]; // } // System.out.println("from:" + start + "to:" + end + " = " + sum); // } else { // int middle = start + (end - start) >> 1; // AddTask subTask1 = new AddTask(start, middle); // AddTask subTask2 = new AddTask(middle, end); // subTask1.fork(); // subTask2.fork(); // } // } // } private static class AddTask extends RecursiveTask { int start, end; public AddTask(int start, int end) { this.start = start; this.end = end; } @Override protected Long compute() { if (end - start <= MAX_NUM) { long sum = 0L; for (int i = start; i < end; i++) { sum += nums[i]; } return sum; } int middle = start + (end - start) >> 1; AddTask subTask1 = new AddTask(start, middle); AddTask subTask2 = new AddTask(middle, end); subTask1.fork(); subTask2.fork(); return subTask1.join() + subTask2.join(); } } public static void main(String[] args) throws IOException { ForkJoinPool fjp = new ForkJoinPool(); AddTask task = new AddTask(0, nums.length); fjp.execute(task); System.in.read(); } }