Open thread, Jan. 12 - Jan. 18, 2015

Gondolinian

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I'm a programmer with a fair amount of reasonably diverse experience, e.g. C, C#, F#, Python, Racket, Clojure and I'm just now trying to learn how to write good Java. I think I understand most of the language, but I don't understand how to like it yet. Most Java programmers seem to basically not believe in many of the ways I have learned to write good software (e.g. be precise and concise, carefully encapsulate state, make small reusable modular parts which are usually pure functions, REPL-driven development, etc. etc.) or they apply them in ways that seem unfortunate to me. However, I feel foolish jumping to the popular conclusion that they are bad and wrong.

I would really like a book -- or heck, just a blog post -- which is like "Java for Functional Programmers" that bridges the gap for me and talks about how idiomatic Java differs from the style I normally consider good and readable and credibly steelmans the Java way. Most of my coworkers either don't like the Java style, only know the Java style, or just don't care very much about this kind of aesthetic stuff, so none of them have been very good at explaining to me how to think about it.

Does this book exist?

(e.g. be precise and concise, carefully encapsulate state, make small reusable modular parts which are usually pure functions, REPL-driven development, etc. etc.)

I am a Java programmer, and I believe in those principles, with some caveats:

Java is verbose. But within the constraints of the language, you should still be as concise as possible.
Encapsulation and reusable modular design is a central goal of the language and OO design in general. I think Java achieves the goal to a significant degree.
Instead of using a REPL, you do edit/compile/run loop

... (read more)

2Viliam_Bur11y

I don't know Java books, but I would like to react to this part anyway: [...] There are much more bad programmers than good programmers, so any language that is sufficiently widely used is necessarily a language mostly used by bad programmers. (Also, if the programming language is Turing-complete, it also means that you can reinvent any historical bad programming practices in that language.) On the other hand, there are often genuine mistakes in the language design, or in the standard libraries. So here is my opinion on which is which in Java: precise and concise -- sorry, no can do. Using proper formatting, merely declaring a read-only integer property of a class will cost you five lines not including whitespace (1 line declaration, 1 line assignment in constructor, 3 lines read accessor). (EDIT: Removed an obsolete info.) carefully encapsulate state -- that's what the "private" and "public" keywords are for. I don't quite understand what could be the problem here (other than bad programmers not using these keywords; or the verbosity). make small reusable modular parts which are usually pure functions -- this is not how Java is typically used, but it can be done. It has the garbage collector. It has immutable types; and for the mutable ones, you could create an immutable wrapper class (yes, a lot of writing again). So you can write a module that gets immutable values as inputs, returns them as outputs, which is more or less what you want. The only problem is that "immutability" is not recognized by the language; you only know that a class is immutable by reading the documentation or looking at the source code; you cannot have the compiler check it for you. REPL-driven development -- it could be technically possible to make an interactive functional shell, and maybe someone already did it. But that's definitely not how Java is typically used. A slightly more traditional solution, although not exactly what you want, would be to use the Groovy language for the i

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