FisherYates.java

import java.util.*;

// This class implements the Fisher-Yates Shuffle Algorithm.
// 
// Author: Charles Reid
// Class: CSC 142
// Date: March 2017

public class FisherYates {
    public static void main(String[] args) {

        // Create the array
        int n = 50;
        double[] z = new double[n];

        // Populate the array
        for(int i=0; i<n; i++) {
            z[i] = (i+1)*100*Math.PI;
        }

        // Before:
        System.out.println(Arrays.toString(z));

        fisherYatesShuffle(z);

        // After:
        System.out.println(Arrays.toString(z));
    }

    public static void fisherYatesShuffle(double[] arr) {
        Random r = new Random();
        int n = arr.length;
        int i = 0;

        // n = 1 corresponds to swapping next-to-last with last
        // n > 1 corresponds to having at least two possible choices
        while( n > 1 ) {
            n--;
            i = r.nextInt(n);
            swap(i,n,arr);
        }
    }

    public static void swap(int i, int j, double[] arr) {
        double temp = arr[j];
        arr[j] = arr[i];
        arr[i] = temp;
    }
}