- Map interface is the not the child interface of collection interface.
- If you want to represent a group of objects as key value pair then we should go for map interface.
- In map both key and values can be objects.
- In map duplicate keys are not allowed but values can be duplicate.
- Dictionary class, Hashtable and Properties class can in java 1.0 version.
- Map, HashMap and WeakHashMap came in java 1.2 version.
- IdentityHashMap and LinkedHashMap came in java 1.4 version.
- Dictionary class, Hashtable and Properties class can in java 1.0 version hence they are considered as legacy classes.
Implementation Class of Map interface :
- LinkedHashMap extends HashMap
- Hashtable extends Dictionary
- Properties extends Hashtable
Features of Map :
- When we need to represent data in the form of Key value paid then we should go for map