Why is Map not considered a collection?

In Java, the Map interface is not a subinterface of Collection because it represents a data structure based on key-value pairs, rather than a set of elements.

Collection is intended for storing and processing groups of similar elements, where each element is a separate object.

Map, on the other hand, stores associations between keys and values, and its methods differ from collection methods: for example, there are no methods for iterating over elements directly, but there are methods for working with keys, values, and pairs.

Therefore, Map and Collection are different interface hierarchies in Java, reflecting different data storage concepts.