Is there a no-duplicate List implementation out there?

Question

I know about SortedSet, but in my case I need something that implements List, and not Set. So is there an implementation out there, in the API or e

Answer 1

NOTE: it does not take subList implementation into account.

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

public class UniqueList extends ArrayList {

    private static final long serialVersionUID = 1L;

    /** Unique elements SET */
    private final Set set=new HashSet();

    /** Used by addAll methods */
    private Collection addUnique(Collection col) {
        Collection unique=new ArrayList();
        for(T e: col){
            if (set.add(e)) unique.add(e);
        }
        return unique;
    }

    @Override
    public boolean add(T e) {
        return set.add(e) ? super.add(e) : false;
    }

    @Override
    public boolean addAll(Collection col) {
        return super.addAll(addUnique(col));
    }

    @Override
    public void add(int index, T e) {
        if (set.add(e)) super.add(index, e);
    }

    @Override
    public boolean addAll(int index, Collection col) {
        return super.addAll(index, addUnique(col));
    }

}