The Java Collections Hierarchy

The abbreviated entry format we use in the descriptions below is

• Object ... this is an ancestor of all other Java classes
  • Dictionary<K,V> ... this name generally identifies a look-up structure
    • Hashtable<K,V> ... an "obsolete" class, use the Map interface instead
  • AbstractCollection<E> (Iterable, Collection) ... an abstract class which must be extended
    • AbstractList<E> (List) ... an abstract class which must be extended
      • Vector<E> (Serializable, Cloneable, RandomAccess)
        • Stack<E>
      • ArrayList<E> (Serializable, Cloneable, RandomAccess)
        • ... other special-purpose subclasses
      • AbstractSequentialList<E> ... an abstract class which must be extended
        • LinkedList<E> (Serializable, Cloneable, Queue)
    • AbstractQueue<E> (Queue) ... an abstract class which must be extended
      • PriorityQueue<E> (Serializable)
      • ... other special-purpose subclasses
    • AbstractSet<E> (Set) ... an abstract class which must be extended
      • HashSet<E> (Serializable, Cloneable)
      • TreeSet<E> (Serializable, Cloneable, SortedSet)
      • ... other special-purpose subclasses
  • AbstractMap<K,V> (Map)
    • HashMap<K,V> (Serializable, Cloneable)
    • TreeMap<K,V> (Serializable, Cloneable, SortedMap)
    • ... other special-purpose subclasses