Generate a Java program to implement Merge Sort algorithm to efficiently sort an array of elements in ascending order.

public class MergeSort {
 
 public static void mergeSort(int[] array) {
  if (array.length > 1) {
   int[] left = leftHalf(array);
   int[] right = rightHalf(array);
 
   mergeSort(left);
   mergeSort(right);
 
   merge(array, left, right);
  }
 }
 
 public static int[] leftHalf(int[] array) {
  int size1 = array.length / 2;
  int[] left = new int[size1];
  for (int i = 0; i < size1; i++) {
   left[i] = array[i];
  }
  return left;
 }
 
 public static int[] rightHalf(int[] array) {
  int size1 = array.length / 2;
  int size2 = array.length - size1;
  int[] right = new int[size2];
  for (int i = 0; i < size2; i++) {
   right[i] = array[i + size1];
  }