Java RecursiveTask create

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveTask;

public class Main {
   public static void main(String[] args) {
      int numbers[] = new int[100000];
      for (int i = 0; i < numbers.length; i++) {
         numbers[i] = i;/*www . ja va 2s.  c o  m*/
      }
      long sum = 0L;
      long startTime = System.currentTimeMillis();
      for (int i = 0; i < numbers.length; i++) {
         sum += numbers[i] * numbers[i];
      }
      System.out.println("Sum of squares: " + sum);
      long stopTime = System.currentTimeMillis();
      System.out.println("Iterative solution time: " + (stopTime - startTime));

      ForkJoinPool forkJoinPool = new ForkJoinPool();
      startTime = System.currentTimeMillis();
      long result = forkJoinPool.invoke(new SumOfSquaresTask(numbers, 0, numbers.length));
      System.out.println("forkJoinPool: " + forkJoinPool.toString());
      System.out.println("forkJoinPool: " + forkJoinPool.toString());
      stopTime = System.currentTimeMillis();
      System.out.println("Sum of squares: " + result);
      System.out.println("Fork/join solution time: " + (stopTime - startTime));
   }
}

class SumOfSquaresTask extends RecursiveTask<Long> {
   private static int numbers[] = new int[100000];
   private int threshold = 1000;
   private int from;
   private int to;

   public SumOfSquaresTask(int[] data, int from, int to) {
      numbers = data;
      this.from = from;
      this.to = to;
   }

   @Override
   protected Long compute() {
      long sum = 0L;
      int mid = (to + from) >>> 1;

      if ((to - from) < threshold) {
         for (int i = from; i < to; i++) {
            sum += numbers[i] * numbers[i];
         }
         return sum;
      } else {
         List<RecursiveTask<Long>> forks = new ArrayList<>();
         SumOfSquaresTask task1 = new SumOfSquaresTask(numbers, from, mid);
         SumOfSquaresTask task2 = new SumOfSquaresTask(numbers, mid, to);
         forks.add(task1);
         task1.fork();
         forks.add(task2);
         task2.fork();

         for (RecursiveTask<Long> task : forks) {
            sum += task.join();
         }
         return sum;
      }
   }
}