CODEWITHSUNDEEP
javajava-8java-stream
Sergiy
Sergiy

Reputation: 2041

Why do we have separate Spliterators class in Java 8?

Why did new Spliterators class appear in Java 8? Since Java 8 we have possibility to add static methods to the interfaces. Since Spliterators class has only static method wouldn't be simpler to declare all its methods in the Spliterator interface?

The same question about Collectors/Collector pair.

Thank you.

Upvotes: 4

Views: 131

Answers (3)

Holger
Holger

Reputation: 298133

It’s perfectly possible that this decision was made without even thinking about this brand new possibility, but simply following the established-since-twenty-years pattern.

Besides that, it can be debated whether it is really useful to add 25 to 30 static methods to an interface. It makes sense to offer a few factories for canonical implementations, but you should draw a line somewhere. It’s not feasible to add factories to all implementations to an interface, just because they are offered by the same library. But this debate would be off-topic.

Further, Spliterators does not only offer static methods, but also nested classes. Unlike static methods, these classes would pollute the name space of every implementation class, when being defined in an interface.

Collectors and Spliterators may also contain implementation-specific non-public methods and even fields.

Upvotes: 9

MatWdo
MatWdo

Reputation: 1740

No, is not good idea, because interface declares a contract, but class represents logic. But after add default method to interface in Java 8 we can only declare public method, but in abstract class we can add public and private abstract method, so we still can hide some logic in abstract classes. Imagine, in actual level of language you can declare only public method, and everyone can change your idea for e.q. Collection

Upvotes: 2

Vladislav Rastrusny
Vladislav Rastrusny

Reputation: 29975

Because there is a difference between an interface and a class. These two have different intentions. Interface declares a contract. Default methods for the interface should be used carefully, for instance, where you can't break compatibility by adding a method declaration into an interface and can't declare xxxV2 interface.

A class is an entity, which represents a unit of the program logic.

Upvotes: 0

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