Permutation of array

Question

For example I have this array:

int a[] = new int[]{3,4,6,2,1};

I need list of all permutations such that if one is like this, {3,2,1

Answer 1

This a 2-permutation for a list wrapped in an iterator

import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

/* all permutations of two objects 
 * 
 * for ABC: AB AC BA BC CA CB
 * 
 * */
public class ListPermutation implements Iterator {

    int index = 0;
    int current = 0;
    List list;

    public ListPermutation(List e) {
        list = e;
    }

    public boolean hasNext() {
        return !(index == list.size() - 1 && current == list.size() - 1);
    }

    public List next() {
        if(current == index) {
            current++;
        }
        if (current == list.size()) {
            current = 0;
            index++;
        }
        List output = new LinkedList();
        output.add(list.get(index));
        output.add(list.get(current));
        current++;
        return output;
    }

    public void remove() {
    }

}