Permutation

package permutation;

import java.util.ArrayList;
import java.util.List;

public class Permutation {

    List<String> results = new ArrayList<String>();

    public static void main(String [] args){
        String inputstring = "STB";
        char[] input = inputstring.toCharArray();
        int n = input.length-1;
        Permutation p = new Permutation();
        p.permute(input, 0, n);
    }
    /**
     * Recusive method to calculate the permutation of a given String.
     * A permutation is the rearrangement of elements of an ordered list
     * - further information @ http://mathworld.wolfram.com/Permutation.html
     * @param input
     * @param i
     * @param n
     */
    private void permute(char[] input, int i, int n){
        if(i == n){
            System.out.println(input);
            results.add(new String(input));
        }
        else{
        for(int j = i; j <= n; j++){
            swap(input, i, j);
            permute(input, i+1, n);
            swap(input, i, j);
        }
        }
    }
    private char[] swap(char[] input, int i, int j){
        char help = input[i];
        input[i] = input[j];
        input[j] = help;
        return input;
    }
}