Merge Sort in Java - Recursive

public class MergeSort {
    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 (int i = 0; i < n1; ++i) L[i] = arr[l + i];
        for (int j = 0; j < n2; ++j) R[j] = arr[m + 1 + j];

        int i = 0, j = 0, k = l;
        while (i < n1 && j < n2) {
            if (L[i] <= R[j]) {
                arr[k] = L[i];
                i++;
            } else {
                arr[k] = R[j];
                j++;
            }
            k++;
        }
        while (i < n1) arr[k++] = L[i++];
        while (j < n2) arr[k++] = R[j++];
    }

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

    public static void main(String args[]) {
        int arr[] = {12, 11, 13, 5, 6, 7};
        new MergeSort().sort(arr, 0, arr.length - 1);
        for(int x: arr) System.out.print(x + " ");
    }
}