/**
* Factory method to create a SetList using the supplied list to retain order.
*
* <p>If the list contains duplicates, these are removed (first indexed one kept). A <code>HashSet
* </code> is used for the set behaviour.
*
* @param <E> the element type
* @param list the list to decorate, must not be null
* @return a new {@link SetUniqueList}
* @throws NullPointerException if list is null
* @since 4.0
*/
public static <E> SetUniqueList<E> setUniqueList(final List<E> list) {
if (list == null) {
throw new NullPointerException("List must not be null");
}
if (list.isEmpty()) {
return new SetUniqueList<E>(list, new HashSet<E>());
}
final List<E> temp = new ArrayList<E>(list);
list.clear();
final SetUniqueList<E> sl = new SetUniqueList<E>(list, new HashSet<E>());
sl.addAll(temp);
return sl;
}
