Why Map Doesn’t Extend Collection Interface in Java?

Learn why the Map interface in Java is not part of the Collection hierarchy. Understand the design reasoning, key differences, and how it benefits the Java Collection Framework.

🔍 Short Answer:

Because Map represents key-value pairs, while Collection represents a group of elements (values only).

➡️ They are conceptually different — that’s why Map doesn’t extend Collection.

🔎 Let’s Break It Down

The collection interfaces are divided into two groups:

The most basic interface, java.util.Collection.

https://www.javaguides.net/2018/08/collections-framework-in-java.html

The other collection interfaces are based on Map:

https://www.javaguides.net/2018/08/collections-framework-in-java.html

✅ 1. Collection is a group of elements

• It includes: List, Set, Queue, etc.
• It focuses on a single group of objects.
• Example:

List<String> names = List.of("Ramesh", "Sita", "Raj");