Contains Duplicate in array at most far k

Given an array of integers and an integer k, find out whether there are two distinct indices i and j in the array such that nums[i] = nums[j] and the absolute difference between i and j is at most k.

Latest Source Code:
Github: ArrayDuplicate.java

Output:

Array: [1, 3, 4, 2, 1, 5]
K : 5
Is exists? true