Collection
Sets
HashSet – implements set, backed by hash table
LinkedHashSet – implements set, backed by hash table and linked list (predictable order)
SortedSet – set with natural or Comparator ordering
NavigableSet – sorted set extended with navigation methods: lower, floor, ceiling, higher
TreeSet – implements sorted and navigable set backed by tree map
Ordered Lists
List – ordered sequence
ArrayList – non synchronized resizable array, internaly stored as []
LinkedList – non synchronized double-linked list and deque implementation (List list = Collections.synchronizedList(new LinkedList(…));)
Vector – legacy array implementation
Stack Class
Stack – extend Vecor as LIFO stack
Queues
Queue – collection for holding elements prior to processing
PriorityQueue – ordered queue based on natural ordering or Comparator
Double-ended queues
Deque – collection that support both end, first and last element processing
ArrayDeque – array implementation of deque
LinkedList – deque implementation
Maps
Hashtable – legacy implementation of hash map
HashMap – Order no guarantee order will remain constant over time Get/put remove containsKey O(1) Interfaces Map Null values/keys allowed Fail-fast behavior Fail-fast behavior of an iterator cannot be guaranteed impossible to make any hard guarantees in the presence of unsynchronized concurrent modification Implementation buckets Is synchronized implementation is not synchronized
LinkedHashMap – Order insertion-order Get/put remove containsKey O(1) Interfaces Map Null values/keys allowed Fail-fast behavior Fail-fast behavior of an iterator cannot be guaranteed impossible to make any hard guarantees in the presence of unsynchronized concurrent modification Implementation double-linked buckets Is synchronized implementation is not synchronized
SortedMap – provide map ordered base on natural ordering or Comparator
NavigableMap – sordet map extended with navigation: lowerEntry, floorEntry, ceilingEntry, and higherEntry. lowerKey, floorKey, ceilingKey, and higherKey return only the associated keys
TreeMap – Order sorted according to the natural ordering (compareTo or externally supplied Comparator) Get/put remove containsKey O(log(n)) Interfaces NavigableMap Map SortedMap Null values/keys only values Fail-fast behavior Fail-fast behavior of an iterator cannot be guaranteed impossible to make any hard guarantees in the presence of unsynchronized concurrent modification Implementation Red-Black Tree Is synchronized implementation is not synchronized
WeakHashMap – hash map implementation with key removing when is no longer in ordinary use
EnumMap
IdentityHashMap