Generating all permutations of a given string

Question

What is an elegant way to find all the permutations of a string. E.g. permutation for ba, would be ba and ab, but what about longer st

Answer 1

This is what I did through basic understanding of Permutations and Recursive function calling. Takes a bit of time but it's done independently.

public class LexicographicPermutations {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    String s="abc";
    Listcombinations=new ArrayList();
    combinations=permutations(s);
    Collections.sort(combinations);
    System.out.println(combinations);
}

private static List permutations(String s) {
    // TODO Auto-generated method stub
    Listcombinations=new ArrayList();
    if(s.length()==1){
        combinations.add(s);
    }
    else{
        for(int i=0;itemp=permutations(s.substring(0, i)+s.substring(i+1));
            for (String string : temp) {
                combinations.add(s.charAt(i)+string);
            }
        }
    }
    return combinations;
}}

which generates Output as [abc, acb, bac, bca, cab, cba].

Basic logic behind it is

For each character, consider it as 1st character & find the combinations of remaining characters. e.g. [abc](Combination of abc)->.

1. a->[bc](a x Combination of (bc))->{abc,acb}
2. b->[ac](b x Combination of (ac))->{bac,bca}
3. c->[ab](c x Combination of (ab))->{cab,cba}

And then recursively calling each [bc],[ac] & [ab] independently.