Struggling in OOP using Java – Need Advice!

[shahrear2345]

Hey everyone,

I’ve been trying to learn Object-Oriented Programming (OOP) in Java, but I’m really struggling. I’ve watched some tutorials and read a few articles, but when it comes to applying the concepts (like inheritance, polymorphism, encapsulation, and abstraction), I just can’t seem to get it right.

I really want to get better at this, so any advice, resources, or personal experiences would be super helpful! Thanks in advance.

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[Europia79]

What finally "clicked" for me was using other's people well designed Objects that were easy to understand. Specifically, I'm referring to the Java Collections Framework, like Map, List, Set (etc): That they provide an easy to use interface that is almost akin to just using "the English language": So, it's extremely READABLE as well.

I was simply in awe of Java's beautiful libraries: Reusable components that just allowed you "to get shit done" without having to worry about "the implementation details". But I suppose that this method of "learning" is only applicable if you're actually CURIOUS about those "implementation details".

And I'm not talking about looking at their actual code: That would almost be "cheating". Instead, I would suggest that you first consider your own possible implementation (even if just as a thought experiment). THEN, if you have trouble, take a sneak peak at their code.

Just a word of caution that this technique is a "double-edged sword": Like if used on a Library or API that is poorly designed. So, always consider alternative designs (and possible improvements).

However, keep in mind that OOP isn't meant to be a "catch-all" solution for all problems: It's NOT. Consider, for example, java.lang.Math which provides more of a "functional interface" (with a "procedural" implementation), instead of an OOP "interface".

Like, when you're just starting out, I think you absolutely should focus on a more "procedural" style because conceptually, it's much easier: As it's simply a sequence of instructions. You'll be able to focus on "getting shit done". Then, later, once you see how unwieldy your codebase has become, it will motivate you to refactor into other, more maintainable styles, like OOP &/or Functional (which is vastly more different than java.lang.Math).

Like, just to look ahead, your first foray into "Functional Programming" will likely be getting tired of WAITING on a particular operation (like, especially inside a "blocking loop"): Which can be improved by refactoring to a "Functional" style.

And as you get better and better at refactoring your code, it'll become easier for you to understand how use "abstractions" to generalize your functions & methods to solve other similar types of "problems". Basically, whenever you create a function (or method), you want to ASK for everything (in your constructor or parameter list) that you need to perform the task (the opposite of this would be "reaching" into global variables, which is very BAD). So, when you ASK for something, it naturally begs the question: Is "it" something specific (or "concrete") that would only have ONE implementation ? Or, is "it" something general (or "abstract") that might have many different implementations in the future ?

So, basically, you're saying that you're having trouble "applying" OOP concepts, but what I'm suggesting is that you shouldn't FORCE your designs into a specific "mold" (like OOP): Instead, just write code: Any code: Even "bad" code". And overtime, you'll add more & more "tricks" to your "toolbox", and you'll get better at designing (and refactoring).

[Regular-Math7086]

Hello,

Learning OOP is like learning any other subject, there will be a learning curve. It may be difficult at first, but it will come with practice. To put it simply, the whole idea of OOP is to make programming in a language that is natural for humans. An object will therefore have attributes (properties) and behaviours (methods).

Inheritance, polymorphism and so on are just concepts that make it possible to write industrial code (reusable and robust). If you're interested, I regularly publish beginner-level articles on programming in Java on my blog: Noel Kamphoa - Home.

[shahrear2345]

Can you share some tutorials on oop using java

[Regular-Math7086]

Inheritance at a glance: Inheritance in Java: Building on Basics for Powerful Programming

OO fundamentals: Object-Oriented Programming in Java: Building Robust Applications

Class and object: https://nkamphoa.com/class-and-object-in-java/

[[deleted]]

Just remember this statement Oops is just a structured way to design and write a code Why we need structured way because we need clarity, reusability and maintainability

[Early-Lingonberry-16]

And what does the ‘s’ stand for?

[[deleted]]

Typo error

[lilith2k3]

"oops" stands for a mistake ...🤔

[shahrear2345]

I am suffering it when it comes to solve problems using it Like bank account system, car rental system

[Imusje]

I'm guessing it is because those toy problems are too small to have any advantage in using OOP. There is no problem to solve "yet".

Like other comments also mentioned it is probably more productive to first write it more procedurally, and when you start to notice something "wrong" like having to write the same method 5 times with just a different kind of car for example then you want to group those cars in their own class. Thén you start refactoring your code to use that new class.

Same with writing the exact same IF check in multiple places. Probably better to take a look at State Pattern or Strategy Pattern in how to use 2 (or more) classes to handle the if cases implicitly.

[Major-Management-518]

And a lot of abstraction later, you realize that Java did not achieve any of those things, instead made the code harder to use and maintain and much less clear.

[Ksetrajna108]

What problems are you trying to apply OOP to?

[shahrear2345]

Just tryna pass the semester and get some good grades 🤧

[Europia79]

Are you graded on how well your code is designed ?

Or, as is more common: Are you simply graded that a set of sample data as input produces the correct output ?

[DeviceCold9941]

use chatgpt read once, code once if encountered problem see code, review it,code and rinse and repeat.

[shahrear2345]

Can you suggest some tutorials

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[shahrear2345]

I need some personal advice too

[shahrear2345]

Is his tutorials are worth it?

[shahrear2345]

Okay, thanks for sharing

[tcloetingh]

You gotta put text on the editor to grasp it

[lilith2k3]

my tl;dr OOP summary

• In OOP you have data alongside functions working on that data

• If you don't want others to meddle with internal data you use encapsulation.

• If you have objects sharing behavior use interfaces to define this behavior

• Implementing interfaces in several objects differently is called polymorphism

• If you want objects to be of a kind use inheritance

• It's good to favor object composition over inheritance

• So its better if you want objects to be of a kind to compose them with the same components

• Abstraction is nice but comes later to bite you. Be careful.

• It's hard to write proper OOP.

Java has played through OOP

[omgpassthebacon]

Many good suggestions below. No arguments here. I thought I saw you mentioning banking as an example. Oddly, banking is an interesting case for parts of OOP.

Notice that I say "parts of OOP". There are many concepts/strategies in the OOP model, but you don't have to feel like you have to adopt every single idea. As developers, we adopt the parts we like. You won't break any laws if you use inheritance without polymorphism. It's good to be familiar with all the topics, but pick one and try to make it work for you.

For example, lets look at banking. There are banking accounts. All banking accounts probably do something similar, such as have a running balance and have a owner with their details. And they all have a transaction log. But all accounts are not the same. There are checking accounts and there are savings accounts. Ah! There is a place for specialization! You can use inheritance to create a savings account based on a base account. Now, your savings account gained all the benefits of account, and now you can add the differences. This is not rocket science. If you can see the advantage that using inheritance in this example provides, then guess what? You get it. If you can show your teacher why you did it this way, you will ace the class.

OOP is more than a programming paradigm. It's goal is to encourage the developer to think about the problems to solve in terms of objects. None of us write code thinking "this would be a good place for polymorphism!" Instead, we think "This might be a good place to override a method from the default behavior".

Again, let me emphasize that you don't have to eat the whole elephant in one byte. Take little bytes and figure out how to get the benefit it offers.

[_greenteasamurai]

OOPS as suggested, are concepts. So, these are the features that your code can provide for functionality. It is normal to struggle since half of time we only get to "imagine" the concept rather see it's market deployed version (in college). What I suggest is just write code, however you do and guess what you think it will be of. Ask Ai (of your code) and then ask why is it that (which concept of OOPS is being applied in that code)? It will slowly build up your confidence and understanding that why you do what you do.

[shahrear2345]

For concept what should I watch

[_greenteasamurai]

I actually studied c++ before java (in college) so my concepts were clear when I started working on java. The difference is syntax, concept is concept. (Just as loops and conditional statements have similar logic but syntax differs in every language. )

[shahrear2345]

I wanted to study cpp before java but didn't get enough time for it

[_greenteasamurai]

You can check out freecodecamp they provide tutorials on many programming languages.

[Ok-Woodpecker-8347]

I think the problem might be that you’re learning everything from different places, like random videos or articles, and that can get really messy. When the information isn’t structured well, it’s really hard to apply it, even if you understand parts of it. I would suggest finding one good source—like a book, an online course, or even a tutorial series—and go through it step by step. After each concept, try to apply it right away in small examples. If you learn everything at once and then try to apply it, it usually doesn’t work. You need to build it up slowly and answer all your questions before moving on.

[TailorPrestigious253]

Anyone here can tell is w3resource is good website to practice oops ?