Permutation algorithm for array of integers in Java

Question

I have a working example to generate all char permutations in a String as below:

static ArrayList permutations(String s) {
        if (s == nul         


        

Answer 1

This code takes String elements, but can me modified to work for integers:

import java.util.*;
/**
 * Write a description of class GeneratePermutations here.
 * 
 * @author Kushtrim 
 * @version 1.01
 */
public class GeneratePermutations

{
    public static void main(String args[])
    {
        GeneratePermutations g = new GeneratePermutations();
        String[] elements = {"a","b","c",};
        ArrayList permutations = g.generatePermutations(elements);

        for ( String s : permutations)
        {
            System.out.println(s);
        }
        //System.out.println(permutations.get(999999));
    }

    private ArrayList generatePermutations( String[] elements )
    {
        ArrayList permutations = new ArrayList();
        if ( elements.length == 2 )
        {

            String x1 = elements[0]  + elements[1]; 
            String x2 = elements[1]  + elements[0];  
            permutations.add(x1);
            permutations.add(x2);

        }
        else {
            for (  int i = 0 ; i < elements.length  ; i++)
            {
                String[] elements2 = new String[elements.length -1];
                int kalo = 0;
                for( int j =0 ; j< elements2.length ; j++ )
                {
                    if( i == j)
                    {
                        kalo = 1;
                    }
                    elements2[j] = elements[j+kalo];
                }
                ArrayList k2 = generatePermutations(elements2);
                for( String x : k2 )
                {
                    String s = elements[i]+x;
                    permutations.add(s);
                }
            }
        }

        return permutations;
    }
}