Collections

Stack

Map

Type	Method	Description
V	put(K key, V value)	Associates the specified value with the specified key in this map (optional operation).
V	putIfAbsent(K key, V value)	If the specified key is not already associated with a value (or is mapped to null) associates it with the given value and returns null, else returns the current value.
void	putAll(Map<? extends K, ? extends V> m)	Copies all of the mappings from the specified map to this map (optional operation).
boolean	containsKey(Object key)	Returns true if this map contains a mapping for the specified key.
boolean	containsValue(Object value)	Returns true if this map maps one or more keys to the specified value.
V	get(Object key)	Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
V	getOrDefault(Object key, V defaultValue)	Returns the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key.
Map.Entry<K,V>	entrySet()	Returns a Set view of the mappings contained in this map.

merge(K key, V value, BiFunction<? super V, ? super V, extends V> remappingFunction)

V computeIfAbsent(K key, Function<K, V> mappingFunction)

Operation	HashMap	TreeMap	LinkedHashMap
Insertion	\(O(1)/O(\log{n})\)	\(O(\log{n})\)	\(O(1)/O(n)\)
Deletion	\(O(1)/O(\log{n})\)	\(O(\log{n})\)	\(O(1)/O(n)\)
Search	\(O(1)/O(\log{n})\)	\(O(\log{n})\)	\(O(1)/O(n)\)

Queue

PriorityQueue

• PriorityQueue()

• PriorityQueue(int initialCapacity)

• PriorityQueue(Comparator comparator)