Difference between HashMap and Map in Java..?

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Java - HashMap vs Map objects

I want to know the difference between HashMap and Map in java..??

http://stackoverflow.com/questions/1348199/java-hashmap-vs-map-objects — DarthVader, Mar 06 '12 at 17:39

score 79 · Answer 1 · answered Mar 06 '12 at 17:39

79

Map is an interface, i.e. an abstract "thing" that defines how something can be used. HashMap is an implementation of that interface.

answered Mar 06 '12 at 17:39

Lars Kotthoff

score 33 · Answer 2 · edited Jun 20 '20 at 09:12

33

Map<K,V> is an interface, HashMap<K,V> is a class that implements Map.

you can do

Map<Key,Value> map = new HashMap<Key,Value>();

Here you have a link to the documentation of each one: Map, HashMap.

edited Jun 20 '20 at 09:12

Community

answered Mar 06 '12 at 17:41

WalterM

score 7 · Answer 3 · answered Mar 06 '12 at 17:40

7

Map is an interface; HashMap is a particular implementation of that interface.

HashMap uses a collection of hashed key values to do its lookup. TreeMap will use a red-black tree as its underlying data store.

answered Mar 06 '12 at 17:40

duffymo

score 5 · Answer 4 · answered Mar 06 '12 at 17:39

5

Map is an interface in Java. And HashMap is an implementation of that interface (i.e. provides all of the methods specified in the interface).

answered Mar 06 '12 at 17:39

smessing

score 3 · Answer 5 · edited Jul 07 '16 at 22:08

3

HashMap is an implementation of Map. Map is just an interface for any type of map.

edited Jul 07 '16 at 22:08

Stephan Herrmann

answered Mar 06 '12 at 17:40

aseychell

5 Answers5