The Set interface inherits its methods from Collection (java.util.Collection) and contains only those methods. In addition to sets, there are queues (java.util.Queue) and maps (java.util.Map).

Why should you use Collections class methods rather than similarly named fields to obtain empty collections? Type safety makes the crucial difference.

Java's collections framework has long needed a collection type that represents a sequence of elements with a defined encounter order and a uniform set of operations that apply across such collections.

Proposal for enhancing the Java programming language would define interfaces for sequenced collections, sequenced sets, and sequenced maps.