Set is an interface available in the java.util package. The Set interface is further implemented by the java.util.HashSet and java.util.LinkedHashSet classes, and it is extended by the java.util.SortedSet interface. The SortedSet interface is implemented by the java.util.TreeSet class.
When discussing Set type collections, it's important to keep the following points in mind:
1. Set collections do not store duplicate elements.
2. Set collections are not synchronized.
3. Enumeration cannot be used to traverse a Set collection, unlike Vector and Stack.
4. List-Iterator cannot be used to traverse a Set collection.
5. All Set type collections are eligible for cloning and serialization as they implement the java.lang.Cloneable and java.io.Serializable interfaces.
java.util.HashSet:
public class java.util.HashSet<E> extends java.util.AbstractSet<E> implements java.util.Set<E>, java.lang.Cloneable, java.io.Serializable {
static final long serialVersionUID;
public java.util.HashSet();
public java.util.HashSet(java.util.Collection<? extends E>);
public java.util.HashSet(int, float);
public java.util.HashSet(int);
java.util.HashSet(int, float, boolean);
public java.util.Iterator<E> iterator();
public int size();
public boolean isEmpty();
public boolean contains(java.lang.Object);
public boolean add(E);
public boolean remove(java.lang.Object);
public void clear();
public java.lang.Object clone();
public java.util.Spliterator<E> spliterator();
static {};
}
java.util.LinkedHashSet:
public class java.util.LinkedHashSet<E> extends java.util.HashSet<E> implements java.util.Set<E>, java.lang.Cloneable, java.io.Serializable {
public java.util.LinkedHashSet(int, float);
public java.util.LinkedHashSet(int);
public java.util.LinkedHashSet();
public java.util.LinkedHashSet(java.util.Collection<? extends E>);
public java.util.Spliterator<E> spliterator();
}
java.util.SortedSet:
public interface java.util.SortedSet<E> extends java.util.Set<E> {
public abstract java.util.Comparator<? super E> comparator();
public abstract java.util.SortedSet<E> subSet(E, E);
public abstract java.util.SortedSet<E> headSet(E);
public abstract java.util.SortedSet<E> tailSet(E);
public abstract E first();
public abstract E last();
public java.util.Spliterator<E> spliterator();
}
java.util.TreeSet:
public class java.util.TreeSet<E> extends java.util.AbstractSet<E> implements java.util.NavigableSet<E>, java.lang.Cloneable, java.io.Serializable {
java.util.TreeSet(java.util.NavigableMap<E, java.lang.Object>);
public java.util.TreeSet();
public java.util.TreeSet(java.util.Comparator<? super E>);
public java.util.TreeSet(java.util.Collection<? extends E>);
public java.util.TreeSet(java.util.SortedSet<E>);
public java.util.Iterator<E> iterator();
public java.util.Iterator<E> descendingIterator();
public java.util.NavigableSet<E> descendingSet();
public int size();
public boolean isEmpty();
public boolean contains(java.lang.Object);
public boolean add(E);
public boolean remove(java.lang.Object);
public void clear();
public boolean addAll(java.util.Collection<? extends E>);
public java.util.NavigableSet<E> subSet(E, boolean, E, boolean);
public java.util.NavigableSet<E> headSet(E, boolean);
public java.util.NavigableSet<E> tailSet(E, boolean);
public java.util.SortedSet<E> subSet(E, E);
public java.util.SortedSet<E> headSet(E);
public java.util.SortedSet<E> tailSet(E);
public java.util.Comparator<? super E> comparator();
public E first();
public E last();
public E lower(E);
public E floor(E);
public E ceiling(E);
public E higher(E);
public E pollFirst();
public E pollLast();
public java.lang.Object clone();
public java.util.Spliterator<E> spliterator();
static {};
}
