Method iterator() declared in java.util.Collection and in java.lang.Iterable, its superinterface?

Question

Can somebody explain to me why is the method Iterator iterator(); defined in java.util.Collection? Collection already extends java.l

Answer 1

The Collection interface was introduced in Java 1.2 with the Collections API. The iterator method was present then. However, the Iterable interface wasn't introduced until Java 1.5. The reason that Collection explicitly defines iterator is because it predates Iterable. The idea of a Collection returning an Iterator predates the idea of Iterable.