package juc;

import java.util.concurrent.ForkJoinPool;

import java.util.concurrent.Future;

import java.util.concurrent.RecursiveTask;

/**

* Created by 李恒名 on 2017/6/19.

*/

public class ForkJoinTest {

static class Sum extends RecursiveTask<Long> {

private static final int THRESHOLD = 10;//可直接求解的临界值

private final long from;

private final long to;

Sum(long from, long to) {

this.from = from;

this.to = to;

}

@Override

protected Long compute() {

long sum = 0;

if ((to - from) < THRESHOLD) {//达到直接求解的临界点，直接进行计算

for (long i = from; i <= to; i++) {

sum = sum + i;

}

} else {//递归分解计算

long mid = (from + to) >>> 1;//取中间值

//以中间值为界将计算任务分解执行

Sum left = new Sum(from, mid);

left.fork();

Sum right = new Sum(mid + 1, to);

right.fork();

//合并计算结果

sum = left.join() + right.join();

}

return sum;

}

}

public static void main(String[] args) throws Exception {

ForkJoinPool forkJoinPool = new ForkJoinPool();

Future<Long> result = forkJoinPool.submit(new Sum(1, 10000));

System.out.println("Sum：" + result.get());//Sum：50005000

}

}