package forkjoin;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ForkJoinPool;

import java.util.concurrent.ForkJoinTask;

import java.util.concurrent.RecursiveTask;

/**

* @author ： CodeWater

* @create ：2022-06-03-20:50

* @Function Description ：分支合并操作：1+2+。。。+100，分成多个子任务进行

*/

class MyTask extends RecursiveTask<Integer>{

//拆分差值不能超过10，计算10以内运算

private static final Integer VALUE = 10;

//拆分开始值

private int begin;

//拆分结束值

private int end ;

//返回结果

private int result ;

//创建有参数构造

public MyTask( int begin , int end ){

this.begin = begin;

this.end = end;

}

//拆分和合并过程

@Override

protected Integer compute(){

//判断相加两个数值是否大于10

if( end - begin <= VALUE ){

//相加操作

for( int i = begin ; i <= end ; i++ ){

result = result + i;

}

}else{//进一步拆分

//获取中间值

int middle = ( begin + end ) / 2;

//拆分左边

MyTask task01 = new MyTask( begin , middle );

//拆分右边

MyTask task02 = new MyTask( middle + 1 , end );

//调用方法拆分

task01.fork();

task02.fork();

//合并结果

result = task01.join() + task02.join();

}

return result;

}

}

public class ForkJoinDemo {

public static void main(String[] args) throws ExecutionException, InterruptedException {

//创建MyTask对象

MyTask myTask = new MyTask( 0 , 100 );

//创建分支合并池对象

ForkJoinPool forkJoinPool = new ForkJoinPool();

ForkJoinTask<Integer> forkJoinTask = forkJoinPool.submit( myTask );

//获取最终合并之后结果

Integer result = forkJoinTask.get();

System.out.println( result );

//关闭池对象

forkJoinPool.shutdown();

}

}