What is the difference between Map and HashMap in java?

Question

Can you please explain the difference between map and hashmap?

How they are different from each other?

Answer 1

Hi Sanhati,

I understand your doubt regarding map and hash map.

Please check out my answer, I hope it will clear your doubts.

Hash map: 

• It is the implementation of map interface.
• It can contain null values and keys.
• It doesn't maintain input order.

Map: 

• It is an interface
• Map has two implementation

1. Tree Map
2. Hash Map

• Tree Map maintains the input order .
• It will not allow any null values.
• Duplicate keys are not allowed in the map

Answer 2

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