Fork/Join小例子 求和

2、从网上找的一个例子，求和

public class CountTask extends RecursiveTask<Integer>
{
    // 阈值，分割小任务计算求和的个数
    private static final int THRESHOLD = 1000;

    private int start;

    private int end;

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

    @Override
    protected Integer compute()
    {
        int sum = 0;
        boolean canCompute = (end - start) <= THRESHOLD;
        if (canCompute)
        {
            for (int i = start; i <= end; i++)
                sum += i;
        }
        else
        {
            //如果任务大于阀值，就分裂成两个子任务计算
            int mid = (start + end) / 2;
            CountTask leftTask = new CountTask(start, mid);
            CountTask rightTask = new CountTask(mid + 1, end);

            //执行子任务
            leftTask.fork();
            rightTask.fork();

            //等待子任务执行完，并得到结果
            int leftResult = (int)leftTask.join();
            int rightResult = (int)rightTask.join();

            sum = leftResult + rightResult;
        }

        return sum;
    }

    public static void main(String[] args)
    {
        ForkJoinPool forkJoinPool = new ForkJoinPool();

        //生成一个计算任务，负责计算从1加到 10000
        CountTask task = new CountTask(1, 10000);
        Future<Integer> result = forkJoinPool.submit(task);
        try
        {
            System.out.println(result.get());
        }
        catch (Exception e)
        {
        }
    }
}