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

public class MergeSort {

    private int[] numbers;
    private int[] helper;

    private int number;

    public void sort(int[] values) {
        this.numbers = values;
        number = values.length;
        this.helper = new int[number];
        mergesort(0, number - 1);
    }

    private void mergesort(int low, int high) {
        // check if low is smaller then high, if not then the array is sorted
        if (low < high) {
            // Get the index of the element which is in the middle
            int middle = low + (high - low) / 2;
            // Sort the left side of the array
            mergesort(low, middle);
            // Sort the right side of the array
            mergesort(middle + 1, high);
            // Combine them both
            merge(low, middle, high);
        }
    }

    private void merge(int low, int middle, int high) {

        // Copy both parts into the helper array
        for (int i = low