Multi Threaded Merge Sort

import java.util.Random;

class Demontration {
  public static void main(String[] args) throws Exception {
    MultiThreadedMergeSort.runTest();
  }
}

class MultiThreadedMergeSort {

  private final int[] duplicate;

  public MultiThreadedMergeSort(int size) {
    duplicate = new int[size];
  }

  public void sort(int left, int right, int[] array) throws InterruptedException {
    if (left >= right) {
      return;
    }
    int mid = (left + right) >> 1;

    Thread sortLeft =
        new Thread(
            () -> {
              try {
                sort(left, mid, array);
              } catch (InterruptedException e) {

              }
            });

    Thread sortRight =
        new Thread(
            new Runnable() {

              @Override
              public void run() {
                try {
                  sort(mid + 1, right, array);
                } catch (InterruptedException e) {

                }
              }
            });

    sortLeft.start();
    sortRight.start();

    sortLeft.join();
    sortRight.join();

    for (int k = left; k <= right; k++) {
      duplicate[k] = array[k];
    }

    int i = left;
    int j = mid + 1;
    int index = left;

    while (i <= mid && j <= right) {
      if (duplicate[i] < duplicate[j]) {
        array[index++] = duplicate[i++];
      } else {
        array[index++] = duplicate[j++];
      }
    }

    while (i <= mid) {
      array[index++] = duplicate[i++];
    }

    while (j <= right) {
      array[index++] = duplicate[j++];
    }
  }

  public static void runTest() throws InterruptedException {
    Random random = new Random(System.currentTimeMillis());
    int size = 10;

    MultiThreadedMergeSort multiThreadedMergeSort = new MultiThreadedMergeSort(size);
    int[] array = new int[size];
    for (int i = 0; i < size; i++) {
      array[i] = random.nextInt(100);
    }
    System.out.println("Before sorting");
    printArray(array);

    multiThreadedMergeSort.sort(0, size - 1, array);

    System.out.println("After sorting");
    printArray(array);
  }

  private static void printArray(int[] array) {
    for (int i = 0; i < array.length; i++) {
      System.out.print(array[i] + " ");
    }
    System.out.println();
  }
}