Summary of Interfaces

The JavaTM Tutorial

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Trail: Collections
Lesson: Interfaces

## Summary of Interfaces

> The core collection interfaces are the foundation of the Java Collections Framework.

> The Java Collections Framework hierarchy consists of two distinct interface trees:

> - The first tree starts with the `Collection` interface, which provides for the basic functionality used by all collections, such as `add` and `remove` methods. Its subinterfaces — `Set`, `List`, and `Queue` — provide for more specialized collections.

>   The `Set` interface does not allow duplicate elements. This can be useful for storing collections such as a deck of cards or student records. The `Set` interface has a subinterface, `SortedSet`, that provides for ordering of elements in the set.

>   The `List` interface provides for an ordered collection, for situations in which you need precise control over where each element is inserted. You can retrieve elements from a `List` by their exact position.

>   The `Queue` interface enables additional insertion, extraction, and inspection operations. Elements in a `Queue` are typically ordered in on a FIFO basis.

> - The second tree starts with the `Map` interface, which maps keys and values similarly to a `Hashtable`.

>   `Map`'s subinterface, `SortedMap`, maintains its key-value pairs in ascending order or in an order specified by a `Comparitor`.

> These interfaces allow collections to be manipulated independently of the details of their representation.

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