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 main(String[] args) {
        int arr[] = {12, 11, 13, 5, 6, 7};
        System.out.println("Given Array");
        printArray(arr);

        MergeSort ob = new MergeSort();
        ob.sort(arr, 0, arr.length-1);

        System.out.println("\nSorted array");
        printArray(arr);
    }

    void sort(int arr[], int l, int r) {
        if (l < r) {
            int m = (l+r)/2;
            sort(arr, l, m);
            sort(arr , m+1, r);
            merge(arr, l, m, r);
        }
    }

    void merge(int arr[], int l, int m, int r) {
        int n1 = m - l + 1;
        int n2 = r - m;

        int L[] = new int [n1];
        int R[] = new int [n2];

        for