A map stores elements in terms of key=value pair. Map<K, V> is the base interface for all kind of maps.

• Sub interfaces: ConcurrentMap<K, V>, SortedMap<K, V>, NavigableMap<K, V> and ConcurrentNavigableMap<K, V>.
• Abstract classes: AbstractMap<E>.
• Implementation classes:
  • Hashtable<K, V>
  • HashMap<K, V>
  • LinkedHashMap<K, V>
  • IdentityHashMap<K, V>
  • ConcurrentHashMap<K, V>
  • ConcurrentSkipListMap<K, V>
  • EnumMap<K extends Enum<K>, V>
  • WeakHashMap<K, V>
  • TreeMap<K, V>

The following class diagram outlines the hierarchy of Map API: