import java.io.Serializable;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
/**
* A thin wrapper around a List transforming it into a modifiable
* Set.
*
* @version $Revision: 2800 $
* @author Jason Dillon
*/
@SuppressWarnings("unchecked")
public class ListSet extends AbstractSet implements Set, Cloneable, Serializable {
/** The serialVersionUID */
private static final long serialVersionUID = 7333619218072079496L;
/** The List which will be used for element storage. */
protected final List list;
/**
* Construct a ListSet.
*
* @param list
* The List which will be used for element storage.
*
* @throws IllegalArgumentException
* List is null or contains duplicate entries.
*/
public ListSet(final List list) {
if (list == null)
throw new RuntimeException("list");
// make sure there are no duplicates
int size = list.size();
for (int i = 0; i < size; i++) {
Object obj = list.get(i);
if (list.indexOf(obj) != list.lastIndexOf(obj)) {
throw new IllegalArgumentException("list contains duplicate entries");
}
}
this.list = list;
}
/**
* Construct a ListSet using an ArrayList for backing.
*/
public ListSet() {
this(new ArrayList());
}
/**
* Construct a ListSet using an ArrayList for backing
* and populated with the given elements.
*
* @param elements
* The elements for the list.
*/
public ListSet(final Collection elements) {
this(new ArrayList(elements));
}
public List getList() {
return list;
}
/**
* Return the size of the set.
*
* @return The size of the set.
*/
public int size() {
return list.size();
}
/**
* Return an iteration over the elements in the set.
*
* @return An iteration over the elements in the set.
*/
public Iterator iterator() {
return list.iterator();
}
/**
* Add an element to the set.
*
* @param obj
* Element to add to the set.
* @return True if the element was added.
*/
public boolean add(final Object obj) {
boolean added = false;
if (!list.contains(obj)) {
added = list.add(obj);
}
return added;
}
/**
* Returns true if this set contains no elements.
*
* @return true if this set contains no elements.
*/
public boolean isEmpty() {
return list.isEmpty();
}
/**
* Returns true if this set contains the specified element.
*
* @param obj
* Element whose presence in this set is to be tested.
* @return true if this set contains the specified element.
*/
public boolean contains(final Object obj) {
return list.contains(obj);
}
/**
* Removes the given element from this set if it is present.
*
* @param obj
* Object to be removed from this set, if present.
* @return true if the set contained the specified element.
*/
public boolean remove(final Object obj) {
return list.remove(obj);
}
/**
* Removes all of the elements from this set.
*/
public void clear() {
list.clear();
}
/**
* Returns a shallow copy of this ListSet instance.
*
* @return A shallow copy of this set.
*/
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
throw new InternalError();
}
}
}