Whoever is demanding every class be an implementation of an interface started thier career in C#, guaranteed.

The main lie about these principles is that they would lead to less maintenance work.

But go ahead and change your database model. Add a field. Then add support for it to your program’s code base. Let’s see how many parts you need to change of your well-architected enterprise-grade software solution.

My opinion is that you are right. I switched to C from an OOP and C# background, and it has made me a happier person.

java is garbage

If it makes the code easier to maintain it’s good. If it doesn’t make the code easier to maintain it is bad.

Making interfaces for everything, or making getters and setters for everything, just in case you change something in the future makes the code harder to maintain.

This might make sense for a library, but it doesn’t make sense for application code that you can refractor at will. Even if you do have to change something and it means a refractor that touches a lot, it’ll still be a lot less work than bloating the entire codebase with needless indirections every day.

Yes OOP and all the patterns are more than often bullshit. Java is especially well known for that. “Enterprise Java” is a well known meme.

The patterns and principles aren’t useless. It’s just that in practice most of the time they’re used as hammers even when there’s no nail in sight.

SOLID is generally speaking a good idea. In practice, you have to know when to apply it.

it sounds like your main beef in Java is the need to create interfaces for every class. This is almost certainly over-engineering it, especially if you are not using dependency inversion. IMHO, that is the main point of SOLID. For the most part your inversions need interfaces, and that allows you create simple, performant unit tests.

You also mention OOP - It has it’s place, but I would also suggest you look at functional programming, too. IMHO, OOP should be used sparingly as it creates it’s own form of coupling - especially if you use “Base” classes to share functionality. Such classes should usually be approached using Composition. Put this another way, in a mature project, if you have to add a feature and cannot do this without reusing a large portion of the existing code without modifications you have a code-smell.

To give you an example, I joined a company about a year ago that coded they way you are describing. Since I joined, we’ve been able to move towards a more functional approach. Our code is now significantly smaller, has gone from about 2% to 60% unit testable and our velocity is way faster. I’d also suggest that for most companies, this is what they want not what they currently have. There are far too many legacy projects out there.

So, yes - I very much agree with SOLID but like anything it’s a guideline. My suggestion is learn how to refactor towards more functional patterns.

99% of code is too complicated for what it does because of principles like SOLID, and because of OOP.

Algorithms can be complex, but the way a system is put together should never be complicated. Computers are incredibly stupid, and will always perform better on linear code that batches similar operations together, which is not so coincidentally also what we understand best.

Our main issue in this industry is not premature optimisation anymore, but premature and excessive abstraction.

If you are creating interfaces for classes that will not have second implementation, that sounds suspicious, what kind of classes are you abstracting? Are those classes representing data? I think I would be against creating interfaces for data classes, I would use records and interfaces only in rare circumstances. Are you complaining about abstracting classes with logic, as in services/controllers? Are you creating tests for those? Are you mocking external dependencies for your tests? Because mocks could also be considered different implementations for your abstractions. Some projects I saw definitely had taken SOLID principles and made them SOLID laws… Sometimes it’s an overzealous architect, sometimes it’s a long-lasting project with no original devs left… The fact that you are thinking about it already puts you in front of many others…

SOLID principles are principles for Object Oriented programming so as others pointed out, more functional programming might give you a way out.

The SOLID principles are just that principles, not rules.

As someone else said, you should always write your code to be maintainable first and foremost, and extra code is extra maintenance work, so should only really be done when necessary. Don’t write an abstract interface unless multiple things actually need to implement it, and don’t refactor common logic until you’ve repeated it ~3 times.

The DRY principle is probably the most overused one because engineers default to thinking that less code = less work and it’s a fun logic puzzle to figure out common logic and abstract it, but the reality is that many of these abstractions in reality create more coupling and make your code less readable. Dan Abramov (creator of React) has a really good presentation on it that’s worth watching in its entirety.

But I will say that sometimes these irritations are truly just language issues at the end of the day. Java was written in an era where the object oriented paradigm was king, whereas these days functional programming is often described as what OO programming looks like if you actually follow all the SOLID principles and Java still isn’t a first class functional language and probably never will be because it has to maintain backwards compatibility. This is partly why more modern Java compatible languages like Kotlin were created.

A language like C# on the other hand is more flexible since it’s designed to be cross paradigm and support first class functions and objects, and a language like JavaScript is so flexible that it has evolved and changed to suit whatever is needed of it.

Flexibility comes with a bit of a cost, but I think a lot of corporate engineers are over fearful of new things and change and don’t properly value the hidden costs of rigidity. To give it a structural engineering analogy: a rigid tree will snap in the wind, whereas a flexible tree will bend.

Like anything else, it can be useful in the right context if not followed too dogmatically, and instead is used when there is a tangible benefit.

For example, I nearly always dependency inject dependencies with I/O because I can then inject test doubles with no I/O for fast and stable integration tests. Sometimes, this also improves re-usability, and for example, a client for one vendor’s API can be substituted with another, but this benefit doesn’t materialize that often. I rarely dependency inject dependencies with no side-effects because it’s rare that any tangible benefit materializes, and everyone deals with the additional complexity for years with no reason. With just I/O dependencies, I’ve generally found no need for a DI container in most codebases, but codebases that dependency inject everything make a DI container basically mandatory, and its usually extra overhead for nothing, IMO. There may be codebases where dependency injecting everything makes perfect sense, but I haven’t found one yet.

I’m a firm believer in “Bruce Lee programming”. Your approach needs to be flexible and adaptable. Sometimes SOLID is right, and sometimes it’s not.

“Adapt what is useful, reject what is useless, and add what is specifically your own.”

“Notice that the stiffest tree is most easily cracked, while the bamboo or willow survives by bending with the wind.”

And some languages, like Rust, don’t fully conform to a strict OO heritage like Java does.

"Be like water making its way through cracks. Do not be assertive, but adjust to the object, and you shall find a way around or through it. If nothing within you stays rigid, outward things will disclose themselves.

“Empty your mind, be formless. Shapeless, like water. If you put water into a cup, it becomes the cup. You put water into a bottle and it becomes the bottle. You put it in a teapot, it becomes the teapot. Now, water can flow or it can crash. Be water, my friend.”

Java is bad but object-based message-passing environments are good. Classes are bad, prototypes are also bad, and mixins are unsound. That all said, you’ve not understood SOLID yet! S and O say that just because one class is Turing-complete (with general recursion, calling itself) does not mean that one class is the optimal design; they can be seen as opinions rather than hard rules. L is literally a theorem of any non-shitty type system; the fact that it fails in Java should be seen as a fault of Java. I is merely the idea that a class doesn’t have to implement every interface or be coercible to any type; that is, there can be non-printable non-callable non-serializable objects. Finally, D is merely a consequence of objects not being functions; when we want to apply a functionf to a value x but both are actually objects, both f.call(x) and x.getCalled(f) open a new stack frame with f and x local, and all of the details are encapsulation details.

So, 40%, maybe? S really is not that unreasonable on its own; it reminds me of a classic movie moment from “Meet the Parents” about how a suitcase manufacturer may have produced more than one suitcase. We do intend to allocate more than one object in the course of operating the system! But also it perhaps goes too far in encouraging folks to break up objects that are fine as-is. O makes a lot of sense from the perspective that code is sometimes write-once immutable such that a new version of a package can add new classes to a system but cannot change existing classes. Outside of that perspective, it’s not at all helpful, because sometimes it really does make sense to refactor a codebase in order to more efficiently use some improved interface.

most things should have an alternate implementation, just in the unit tests. imo that’s the main justification for most of SOLID.

but also I’ve noticed that being explicit about your interfaces does produce better thought out code. if you program to an interface and limit your assumptions about implementation, you’ll end up with easier to reason about code.

the other chunk is consistency is the most important thing in a large codebase. some of these rules are followed too closely in areas, but if I’m working my way through an unfamiliar area of the code, I can assume that it is structured based on the corporate conventions.

I’m not really an oop guy, but in an oop language I write pretty standard SOLID style code. in rust a lot of idiomatic code does follow SOLID, but the patterns are different. writing traits for everything instead of interfaces isn’t any different but is pretty common

One example is creating an interface for every goddamn class I make because of “loose coupling” when in reality none of these classes are ever going to have an alternative implementation.

Not only loose coupling but also performance reasons. When you initialise a class as it’s interface, the size of the method references you load on the method area of the memory (which doesn’t get garbage collected BTW) is reduced.

Also the more I get into languages like Rust, the more these doubts are increasing and leading me to believe that most of it is just dogma that has gone far beyond its initial motivations and goals and is now just a mindless OOP circlejerk.

In my experience, not following SOLID principles makes your application an unmaintainable mess in roughly one year. Though SOLID needs to be coupled with better modularity to be effective.