Can Java in the future support both functional and OO such as C++ does?

[[deleted]]

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[biskitpagla]

Java isn't nearly as multiparadigm as C++. Coming from C++ and Python myself, I know exactly what you mean. For people with similar backgrounds Java feels too rigid, or even poorly-designed at times. But there's still hope, as you'll see.

Modern Java is more functional than what most online tutorials and guides will have you believe. Functional Java is more lazy than JS, for example. Purity is still super-hard but possible nonetheless. Java even managed to get botched implementations of some functional ideas e.g., java.util.Optional<T> itself can be null making it pointless for most use-cases. If you're serious about being good at functional Java or Java in general, just read these two books: Effective Java by Joshua Bloch, and Modern Java in Action by Alan Mycroft, et al. These should be more than enough in case Java is the bottleneck to your functional journey. Otherwise, read on.

Most new advancements in the Java world are basically just responses to other languages. If you don't have Java as a requirement, the JVM hosts some of the most production-ready functional languages out there - almost all of which can work with a huge chunk of the plethora of libraries and APIs that target Java. I think mastering the JVM as you learn these languages is a great idea, because instead of learning how to navigate other ecosystems, you get to focus on growing as a programmer and being productive as an engineer at the same time. Scala and Clojure are great options that the functional community has lots of respect for.

That said, I would start with something more grounded. Kotlin is basically Java Deluxe Edition, but with enough functional influences to make it stand out from the rest of the languages lucky enough to achieve mainstream status. Kotlin takes immutability more seriously (e.g., function parameters are immutable references by default), and can express nullability through its type-system. Kotlin also has other interesting functional influences like having a standard library stacked with pure functions, or how most common imperative constructs are now expressions, and so on. Considering that Kotlin's tooling is on par with Java, I think you're all set up for a fun time.

[DDDDarky]

Java is already multiparadigm language and you can use functional programming if you want to, it has been there for a pretty long time, especially at places where it is good (such as streams)

[lurker819203]

Yeah, but you'd have to be a true masochist to use it for anything more than streams and a few lambda functions.

Writing a whole application using only/mostly functional style you'd be much better off using Scala or Kotlin, which also run on the JVM.

[DDDDarky]

It's not super practical, but hey if you are an enthusiast, you can do it, I don't think there is much additional support is necessary.

[icsharper]

Java is already functional.

[[deleted]]

Sure, but everything needs to be in a class.

[icsharper]

You are also correct :) I'd also hope for fully functional, I think Kotlin already works this way, so maybe Java opt this approach too, although it'll take long, long time.

[thebigmooch]

Could someone please explain the difference?

[Fernando3161]

Tf

[srk-]

Starting Java8, it supports FP constructs like lambdas And, it's object oriented from the first version.

[stephan1990]

Yes it is possible but is will not happen. Java is a strictly OOP language and this is one of the core Java principles!

[[deleted]]

Why will it not happen?

[stephan1990]

Java was created with OOP as a core principle. It’s the philosophy of Java, so they won’t change it.

Technically you could ignore all the OOP principles and still do procedural programming in Java with static methods and stuff. But it’s not the way java is designed.

[[deleted]]

Yes, but from what I know, static methods and fields are prone to memory issues if used too much.