What is AbstractMap In Java ?

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Previously we have discussed about
What is TreeMap In Java ?

Here, we learn What is AbstractMap In Java.But before starting we must know what is Map Interface In Java.?

Class AbstractMap<K,V>

Type Parameters :-

K - the type of keys maintained by this map

V - the type of mapped values

All Implemented Interfaces :-

Map<K,V>

Direct Known Subclasses :-

ConcurrentHashMap, EnumMap, HashMap, IdentityHashMap, TreeMap, WeakHashMap

Declaration of AbstractMap:

public abstract class AbstractMap<K,V>

extends Object

implements Map<K,V>

To implement an unmodifiable map, the programmer needs only to extend this class and provide an implementation for the entrySet method, which returns a set-view of the map's mappings.

This set should not support the add or remove methods, and its iterator should not support the remove method.

To implement a modifiable map, the programmer must additionally override this class's put method and the iterator returned by entrySet().iterator(); must additionally implement its remove method.

Nested Classes :-

Modifier and Type           Class and Description

static class                        AbstractMap.SimpleEntry<K,V> :- An Entry maintaining a key and a value.

static class                      AbstractMap.SimpleImmutableEntry<K,V> :- An Entry maintaining an                                                     immutable key and value.

Constructors :-

Modifier                           Constructor and Description

protected                           AbstractMap() :- Sole constructor.