merge methods

package merge;
import java.util.Scanner;
public class homework4 {
    public static void Divide(int[] ARR, int l, int r){
        if(l < r){
            int m = (l + r);
            Divide(ARR, l, m);
            Divide(ARR, m + 1, r);
            CompareAndMerge(ARR, l, m, r);
        }
    }
    private static void CompareAndMerge(int[] arr, int l, int m, int r) {
        int LArrLenght = m -l +1;
        int RArrLenght = r - m;
        int[] L = new int[LArrLenght];
        int [] R = new int [RArrLenght];
        for(int i = 0; i<LArrLenght; i++) {
            L[i] = arr[l+i];
            }
        for(int j = 0; j< RArrLenght; j++) {
            R[j] = arr[m + 1 + j];
        }
        int i = 0;
        int j = 0;
        int k = l;
        while(i <LArrLenght && j < RArrLenght) {
            if (L[i] < R[j]) {
                arr [k] = L[i];
                i++;
            }else
            {
                arr[k] = R[j];
                j++;
               }
            k++;
            }
           while (i < LArrLenght) {
               arr[k] = L [i];
               i++;
               k++;
           }
           while (j < RArrLenght) {
               arr[k] = L [j];
               j++;
               k++;
         }
    }
}