Java ForkJoinPool use custom ForkJoinTask

import java.util.Date;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.ForkJoinTask;

abstract class MyWorkerTask extends ForkJoinTask<Void> {

  private String name;

  public MyWorkerTask(String name) {
    this.name = name;
  }//from   w  w w  . j  av  a2 s .  c  o  m

  @Override
  public Void getRawResult() {
    System.out.println("get raw result");
    return null;
  }

  @Override
  protected void setRawResult(Void value) {
    System.out.println("set raw result"+ value);
  }

  @Override
  protected boolean exec() {
    Date startDate = new Date();
    compute();
    Date finishDate = new Date();
    long diff = finishDate.getTime() - startDate.getTime();
    System.out.printf("%s : %d Milliseconds to complete.\n", name, diff);
    return true;
  }

  public String getName() {
    return name;
  }

  protected abstract void compute();
}

class Task extends MyWorkerTask {
  private int array[];
  private int start;
  private int end;

  public Task(String name, int array[], int start, int end) {
    super(name);
    this.array = array;
    this.start = start;
    this.end = end;
  }

  @Override
  protected void compute() {
    if (end - start > 100) {
      int mid = (end + start) / 2;
      Task task1 = new Task(this.getName() + "1", array, start, mid);
      Task task2 = new Task(this.getName() + "2", array, mid, end);
      invokeAll(task1, task2);
    } else {
      for (int i = start; i < end; i++) {
        array[i]++;
      }
      try {
        Thread.sleep(50);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
  }
}

public class Main {
  public static void main(String[] args) throws Exception {
    int array[] = new int[10000];
    ForkJoinPool pool = new ForkJoinPool();
    Task task = new Task("Task", array, 0, array.length);
    pool.invoke(task);
    pool.shutdown();
  }
}