Merge sort algorithm

MergeSort.java

package com.example.demo;

public class MergeSort {

    void mergeSort(int[] a, int[] temp, int left, int right) {
        if (left >= right) return;
        int mid = (left + right) / 2;
        mergeSort(a, temp, left, mid);
        mergeSort(a, temp, mid + 1, right);
        merge(a, temp, left, right, mid);
    }

    void merge(int[] a, int[] temp, int left, int right, int mid) {
        for (int i = left; i <= right; i++) {
            temp[i] = a[i];
        }
        int currentLeft = left;
        int currentRight = mid + 1;
        int index = left;
        while (currentLeft <= mid && currentRight <= right) {
            if (temp[currentLeft] <= temp[currentRight]) {
                a[index] = temp[currentLeft];
                currentLeft++;
            } else {
                a[index] = temp[currentRight];
                currentRight++;
            }
            index++;
        }
        for (int i = 0; i <= mid - currentLeft; i++) {
            a[index + i] = temp[currentLeft + i];
        }
    }

}