Java Container's Map interface

Map Interface:

1. The class that implements the Map interface is used to store key-value (key-value) pairs;

2. Map interface implementation class has HASHMAP and TREEMAP, etc.;

3. Key-value pairs stored in the Map class are identified by key, so the key value cannot be duplicated.

4. The common methods of MAP interface are as follows:

4.1 Object put(K key, V value): Associates the specified value with the specified key in this map (optional operation);

4.2 Object Get(Object key): Returns the value mapped by the specified key;

4.3 Object Remove(Object key): If there is a mapping relationship for a key, it is removed from this mapping (optional operation);

4.4 Boolean containskey(Object key): Returns TRUE if this map contains a mapping relationship for the specified key ;

4.5 Boolean containsvalue(Object value): Returns TRUE if the map maps one or more keys to the specified value ;

4.6 int size(): Returns the key-value logarithm in this map;

4.7 int hashcode(): Returns the hash code value for this mapping;

4.8 void Putall(map<?,? >): Copies all mappings from the specified mappings into this map (optional operation).

Java Container's Map interface