Merge Sort Algorithm using Java

MergeSort.java

import java.util.Arrays;

public class MergeSort {

    public static void main(String[] args) {
        int[] arr = new int[]{9, 3, 6, 7, 3, 2, 1, 5, 4, 7, 5};
        mergeSort(arr);
        System.out.println(Arrays.toString(arr));
    }

    public static void mergeSort(int[] inputArray) {
        int inputLength = inputArray.length;

        if (inputLength < 2) {
            return;
        }

        int midIndex = inputLength / 2; // 11 => 5 , 6
        int[] leftHalf = new int[midIndex];
        int[] rightHalf = new int[inputLength - midIndex]; // 11 - 5 = 6

        // populate left array
        for (int i = 0; i < midIndex; i++) {
            leftHalf[i] = inputArray[i];
        }

        // populate right array
        for (int i = midIndex; i < inputLength; i++) {
            rightHalf[i - midIndex] = inputArray[i]; // i = 5 we need index 0 => i - midIndex => 5 - 5 = 0
        }

        mergeSort(leftHalf);
        mergeSort(rightHalf);

        merge(inputArray, leftHalf, rightHalf);


    }

    public static void merge(int[] inputArray, int[] leftHalf, int[] rightHalf) {
        int leftSize = leftHalf.length;
        int rightSize = rightHalf.length;

        int i = 0, j = 0, k = 0;

        while (i < leftSize && j < rightSize) {
            if (leftHalf[i] < rightHalf[j]) {
                inputArray[k] = leftHalf[i];
                i++;
            } else {
                inputArray[k] = rightHalf[j];
                j++;
            }
            k++;
        }

        // add the rest that haven't been added

        while (i < leftSize) {
            inputArray[k] = leftHalf[i];
            i++;
            k++;
        }

        while (j < rightSize) {
            inputArray[k] = rightHalf[j];
            j++;
            k++;
        }
    }
}