C# class to shuffle an array using Fisher-Yates algorithm in order to guarantee a non-repeating list of random integers within a given range

FisherYatesShuffle.cs

using System;

/*
  C# implementation of Fisher-Yates shuffling with automatic reshuffling.

  This class can be used to generate a series of numbers from 0 to ``numElements`` that is guaranteed
  not to repeat. The array is automatically reshuffled when all elements have been picked.
*/

public class FisherYatesShuffling
{
    Random rnd = new Random();
    int[] elements { get; }
    int idx { get; set; } = 0;

    public FisherYatesShuffling(int numElements) {
        if (numElements > 0) {
            elements = new int[numElements];
        } else {
            throw new ArgumentException("numElements must be greater than 0");
        }

        for (int i = 0; i < numElements; i++) {
            elements[i] = i;
        }

        shuffle();
    }

    public void shuffle() {
        for (int i = elements.Length - 1; i > 0; i--) {
            int j = rnd.Next(0, i);
            int t = elements[j];
            elements[j] = elements[i];
            elements[i] = t;
        }

        idx = 0;
    }

    public int getNumber() {
        if (idx >= elements.Length) {
            shuffle();
        }

        int n = elements[idx++];
        return n;
    }
}

// Usage example
class TestShuffle {
    static public void Main(String[] args) {
        int elements = 10;
        FisherYatesShuffling fys = new FisherYatesShuffling(elements);

        // Outputs 2 * "elements" in order to force a reshuffling
        for (int i = 0; i < elements * 2; i++) {
            Console.WriteLine(fys.getNumber());
        }
    }
}