package java.util; public interface Set extends Collection { public int size(); public boolean isEmpty(); public boolean contains(Object o); public Iterator iterator(); public Object[] toArray(); public Object[] toArray(Object[] a); public boolean add(Object o); public boolean remove(Object o); public boolean containsAll(Collection c); public boolean addAll(Collection c); public boolean retainAll(Collection c); public boolean removeAll(Collection c); public void clear(); public boolean equals(Object o); public int hashCode(); }