Merge Sort in Java.

/*
 * Author : Taqui
 * Algorithm Name : Merge Sort
 * Time Complexity : O(n.log(n))
 */

import java.util.Scanner;

public class MergeSort {
    public int[] originalList; // saves the main list of data
    public int[] sortedList; // saves the sorted data
    int size; // total number of data

    public MergeSort(int[] originalList) {
        this.originalList = originalList.clone();
        this.sortedList = originalList;
        this.size = originalList.length;

        divide(0, size - 1); // starting merge sort
    }

    public void divide(int low, int high) {
        if (low != high)
        {
            int middle = (low + high) / 2;
            divide(low, middle); // first half
            divide(middle + 1, high); // second half
            merge(low, high); // sort and join both
        }
    }

    public void merge(int low, int high) {
        int demoList[] = new int[(high - low) + 1]; // demo list to hold the merged data after sorting
        int middle = (low + high) / 2;
        int i1 = low, i2 = middle + 1, I = 0;

        // i1 and i2 will iterate through the first list and second list respectively
        // I will iterate through the demo list to merge sorted data

        while (i1 <= middle && i2 <= high) // i1-> 0 to middle, i2-> middle + 1 to last
        {
            if (sortedList[i1] <= sortedList[i2])
            {
                demoList[I++] = sortedList[i1++];
            }
            else
            {
                demoList[I++] = sortedList[i2++];
            }
        }

        // left over of first list
        while (i1 <= middle)
        {
            demoList[I++] = sortedList[i1++];
        }
        // left over of second list
        while (i2 <= high)
        {
            demoList[I++] = sortedList[i2++];
        }

        // copying back the merged data into main list..to merge this with another sorted list
        for (int i = low; i <= high; i++)
        {
            sortedList[i] = demoList[i - low];
        }
    }

    public static void main(String[] args) {
        Scanner read = new Scanner(System.in);
        System.out.print("Size of the List : ");
        int size = read.nextInt();
        int [] array = new int[size];

        for (int i = 0; i < size; i++)
        {
            System.out.print("\nElement " + (i + 1) + ": ");
            array[i] = read.nextInt();
        }

        System.out.print("\nSorted list: ");
        MergeSort ms = new MergeSort(array);
        for (int i : ms.sortedList)
        {
            System.out.print(i + " ");
        }
    }
}