Java

Difference Map is an interface but HashMap is a class. So you cannot create an object of a Map but you can create an object of a HashMap Map <String , Integer> empIds = new Map<>() ; // This will give a compile time error Map <String , Integer> empIds = new HashMap<>() ; // This is allowed Map contains unique key value pairs but HashMap can have duplicate values. Map interface can be implemented by using its implementing class. Whereas HashMap class implements the Map interface. Map is used to create, Hashmap and TreeMap. While HashMap implements Map interface and extends AbstractMap class. There is no difference between the objects of Map and HashMap. Both of them maintains an insertion order. You are not allowed to use primitive data types (int, float, double, char) to define a Map or a HashMap. You have to use non-primitive data types (Integer, Float, Double, Character, String, Objects) to define a Map or HashMap.  Example of Map public class Maps { ...