Keeping indexes after sorting in Java

Given an integer array, sort its elements in ascending order while retaining and displaying their original indexes, ensuring the initial positions of elements are preserved after sorting.

Examples:

Input: arr[] = {20, 40, 30, 10}

Output:
Element | Original index
10 | 3
20 | 0
30 | 2
40 | 1

Approach

Follow these steps to sort the array while keeping track of original indexes:

• Define a class ArrItem to store each element and its original index.
• Create an ArrayList of ArrItem objects from the array elements.
• Sort the list using Collections.sort() with a custom comparator based on the element value.
• Traverse the sorted list and print each element along with its original index.

Implementation

4 3
5 2
10 1
20 0