hello java fork/join for java

1，示例

import java.util.concurrent.RecursiveTask;

public class Calculator extends RecursiveTask<Integer> {  

    private static final int THRESHOLD = 4;
    private int start;
    private int end;  

    public Calculator(int start, int end) {
        this.start = start;
        this.end = end;
    }  

    @Override
    protected Integer compute() {
        int sum = 0;
        if((end-start) < THRESHOLD){
            for(int i = start; i<= end;i++){
                sum += i;
            }
            System.err.println(">>>>>>>>");
        }else{
            int middle = (start + end) /2;
            Calculator left = new Calculator(start, middle);
            Calculator right = new Calculator(middle + 1, end);
            left.fork();
            right.fork();  

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

}  

2 运行

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.Future;

public class Test {

	/**
	 * @param args
	 * @throws Exception
	 * @throws InterruptedException
	 */
	public static void main(String[] args) throws InterruptedException, Exception {
		// TODO Auto-generated method stub
		ForkJoinPool forkJoinPool = new ForkJoinPool();
		Future<Integer> result = forkJoinPool.submit(new Calculator(0, 9));

		//new Integer(49995000)
		System.err.println(result.get());