r/JavaProgramming • u/MaleficentCarry1704 • 18d ago
r/JavaProgramming • u/Automatic_Coconut676 • 18d ago
Source to Learn Java from Scratch
Hello everybody, so first im willing to start my CS major starting next semester. I dont jnow anything about programming and languages; however, as the summer started and i have 2 months free time, i asked about something i can do that can help me during my major. The answer was is to study JAVA.
In our uni, the first course we take is Java. I got the PDF (249pages) but i want a trusted source to learn Java from Scratch. Im thinking of using sources to schedule my PDF and the trusted source to benefit more.
If you have also any other advice im grateful to read them.
Thank You❤️
r/JavaProgramming • u/Key-Garbage-3782 • 18d ago
Do I need to study lambada?
So I encountered lambada and I thought it is the same as anonymous function in PHP. but java focus more on OOP so top level function is dependent right? it needs functional interface. anonymous function saves time and space but what about lambada? I dont think it saves time and space. NOTE: I am new to lambada
r/JavaProgramming • u/Natural-Shelter-7758 • 19d ago
How Do I Stop Copying Code and Start Thinking Like a Programmer?
I've been learning Java for about a year, but I still don't see much improvement in my coding. I can write basic programs and the code that I learned during my lectures without copying. I'm still learning, but I don't really understand where or when to use many of the concepts, I've studied.
How can I actually learn to write code on my own? I'm so tired of copying and pasting code. I really want to become someone who can build programs from scratch.
Some Java concepts seem easy, and I understand the theory behind them. However, I don't know how to use those concepts in a real program. I often get stuck because I don't know what should come next or what should have been written before. That makes me feel really frustrated.
The images I attached to this post are all for the same project, but have you noticed how different their coding patterns are? That's exactly my problem. Whenever I try to build a simple project like a Banking CLI Simulator or an ATM Simulator without copying someone else's code, I always get stuck. I try my best to think through the logic and write everything myself, but after a while I end up looking at someone else's solution.
How do experienced programmers think through a program? How do you know what to write first, what comes next, and how to connect everything together?
Has anyone else gone through this stage? If so, what helped you finally start writing code independently instead of relying on tutorials or copied code?
I'd really appreciate any advice or suggestions. I genuinely want to improve and become a better programmer.
r/JavaProgramming • u/javinpaul • 18d ago
The Java Developer Reading List (5 Books That Matter)
r/JavaProgramming • u/Swapan-LFE • 19d ago
Foreign Function & Memory API in Java 21
Call native functions from Java 21 without JNI. Practical examples cover downcalls, callbacks, and safe off-heap memory.
r/JavaProgramming • u/Natural-Shelter-7758 • 20d ago
How can i test my java knowledge?
hellow everyone!!
I have been learning Java for about a year. I understand some concepts, but there are still others I don’t fully know. I want to test my knowledge and strengthen my understanding, starting from the very basics. How can I do that? If anyone knows beginner‑friendly Java projects, please share them with me and explain how I can get started.
r/JavaProgramming • u/daanveerKarna • 20d ago
Senior Java/Spring Boot engineers — please drop the interview questions you've been asked or ask others (8–10 YOE level)
I'm preparing for senior Java/Spring Boot interviews (~8–9 YOE level) and I need YOUR help.
Please drop in the comments:
- Questions you've been asked in senior interviews
- Questions you ask candidates when YOU are the interviewer
- Anything that tripped you up or that most people get wrong
I'm looking for real questions across these areas:
**Core Java & JVM**
- GC tuning, memory model, class loading, thread dumps
- Concurrency — ExecutorService, CompletableFuture, virtual threads (Java 21)
**Spring Boot Internals**
- Auto-configuration, bean lifecycle, AOP proxying
- Spring Security — JWT, OAuth2, filter chain
- Spring Data JPA — N+1, lazy loading, optimistic locking
**Caching**
- Redis patterns, eviction, cache invalidation
- Thundering herd, cache stampede prevention
**Kafka & Messaging**
- Partitioning strategy, consumer groups, exactly-once semantics
- Dead letter queues, retry patterns
**Microservices & System Design**
- Saga pattern, circuit breakers, distributed tracing
- API gateway, service mesh, inter-service communication
**Deployment & Observability**
- Kubernetes — HPA, rolling updates, pod disruption budgets
- Blue-green vs canary deployments
- OpenTelemetry, Prometheus, Grafana, structured logging
Please share the actual question text if you can — even a rough version of how it was asked. Bonus points if you share what a great answer looks like vs a mediocre one.
Thank you in advance!
r/JavaProgramming • u/Emergency-Hunter7969 • 20d ago
Should I learn springboot framework ??
So the context is like I have been learning java from several days like the basics and the oops concepts and also with the help of chatgpt and several tools I learned basics of sprinboot just about di and autowiring and few concepts not much and then I am literally thingking is it valuable to learn springboot and spring framework now or should I only focus on dsa I am right in my 3rd year right now so thats my problem. So I request you all guys to please tell me that wether to learn it or not and also If you suggest that to learn please help me some good resources to learn because I am opening a youtube tutorial within few minutes I am getting bored and I am literally closing them so please help me
r/JavaProgramming • u/Fickle_Base_7723 • 20d ago
Package does not exist even though the .JAR files are in the referenced library
I've been trying to solve this problem for the last 4 hours and I couldn't find out why, I asked Gemini, Claude, Copilot Anything you name it, but it's still here and I don't know why VS code can't seem to find the package(I think it's called that) that I need.
r/JavaProgramming • u/BunnyGirlLover-69 • 20d ago
I built an open-source tool to solve the “messy directory” problem by automatically sorting mixed file types into subfolders.
We've all seen that one directory that has 500+ files of completely different formats mixed together. Finding anything in it is a nightmare.
I needed a fast, reliable way to clean up these multi-type directories without doing it manually, so I open-sourced a lightweight utility to do exactly that.
The core workflow:
The target: You point it at a bloated directory containing a massive mix of file types.
Logic: The tool parses the files and maps them to a clean subfolder hierarchy.
Execution: It handles the migration instantly, resolving duplicate file names safely.
No bloated UI, no tracking, no subscription nonsense. Just a straightforward utility that does one job cleanly.
The code is fully open-source here: https://github.com/ShiningPr1sm/File-Organizer
If you have large unorganized datasets or directories, give it a spin. Let me know if you run into any edge cases or file formats it doesn't catch yet, I'm iterating on the sorting logic based on feedback.
r/JavaProgramming • u/javinpaul • 20d ago
Kubernetes Explained Visually: Why It Exists and How All Its Components Work Together
r/JavaProgramming • u/TheHeatYeahBam • 21d ago
I built Protify AI: A strictly zero-dependency, lightweight Java AI SDK (Apache 2.0)
Sharing an open-source project I built earlier this year. It’s an AI SDK for Java, but with a very specific constraint: it has absolutely zero external dependencies. It relies entirely on java.net.http and built-in JSON processing.
- GitHub: https://github.com/protifyconsulting/protifyai-java
- Website / Docs: https://protify.ai
There are great existing options like LangChain4j and Spring AI, but I was frustrated by the large dependency trees they drag into a project. I wanted something lightweight and self-contained that would be good for compliance-driven environments where auditing dependencies is difficult, and the application or service simply doesn't need all of the extra baggage.
Another motivation was pipeline readability. I wanted an explicit, deterministic syntax for chaining multi-step AI tasks across different providers without relying on unpredictable black-box agent loops. I also wanted to be able to plug in virtually any AI provider/LLM in, and built interfaces that provide a pluggable architecture for this purpose.
I am the sole developer on this project. I’ve held back on sharing because I wasn’t sure if the community had an appetite for something like this, but I've found it useful in my own work.
I’m not looking to make money from this—it's licensed under Apache 2.0. I would appreciate thoughts and feedback. If this is conceptually something that others find useful, I'll update it with the most current provider LLMs and keep it updated & support it. Given where AI-driven software development is going, I could see how this sort of thing might not have much use since AI can use other Java libraries, or none at all, to generate the code that will achieve a desired result. That said, I'm curious as to what others think.
I initially started to post this to r/java, but the "no AI" rule indicates I would be irrevocably banned. I can speak to every class and method, and all architectural decisions were mine. I designed the interfaces and sometimes fought with AI coding agents to get it to where I wanted it. I've been a Java developer since the mid-1990s. This is not the result of vibe-coding.
r/JavaProgramming • u/javinpaul • 21d ago
LeetCode was HARD Until I learned these Coding Patterns
r/JavaProgramming • u/Dry_Couple8852 • 22d ago
I can't use the method from another class
the code above is from the method of the main class or main java file(some sort of runner java file)
the "addSong()" method(Custom method) is from another class and another java file but that and the main java file are in the same folder. The first pic was when it is just "void addSong(String input){...}" and the 3rd pic is when the method is "public void addSong(String input){...}".
I fail to see what I did wrong here.
r/JavaProgramming • u/ChanceRaccoon6468 • 22d ago
What is the best desgin pattern for building a resuable pdf genrating module in springboot?
r/JavaProgramming • u/AdLow4135 • 22d ago
hi so i need help with somthing i am making its a dice site its almost done but i am so burnt out i used ai for the most part and it just doesnt work anymore ?
i am a newbie used ai for assitance and everytime i fix somthing somthing new comes out of nowhere
[2026-06-30T20:53:51.491Z] Failed to fetch streamers from origin: Forbidden
owner panel codes dont work
admin panel downt work
keybinds dont work
fix all this
dm me on discord or here for the file if your intrested its a kind of easy for a good programmer i am just bad its a "skill issue"
nvm i got the file very sketchy link
r/JavaProgramming • u/javinpaul • 22d ago
Why Microservices Are Not a Silver Bullet: 10 Reasons to Avoid Them
r/JavaProgramming • u/Excellent_Text1147 • 22d ago
What should I do after learning Core Java concepts
Hey guys!! It's my first time posting on this sub. I am a CS student who will start his 2nd year in a month, i decided to learn the java tech stack for that and have been following the telusko 63 hour video, in which i have completed the core java part. But now instead of starting with maven, i am thinking i should build a project so that the learning of core java doesn't go to waste. What should i do next, mainly what projects should i build to learn, and how?
r/JavaProgramming • u/Kaepsis • 22d ago
I built a CAPTCHA verification system for my Discord bot in Java
r/JavaProgramming • u/javinpaul • 23d ago
The Ultimate Backend Developer Roadmap (2026 Edition)
medium.comr/JavaProgramming • u/yash01411 • 23d ago
Java Development Company | Custom Java Application Development Services
Develop robust, secure, and scalable business applications with expert Java development services. Build custom web applications, enterprise software, cloud-based solutions, APIs, microservices, and mobile backends using the latest Java technologies and frameworks. Whether you're a startup or a large enterprise, Java development solutions help improve operational efficiency, streamline business processes, and support digital transformation. Leverage Java, Spring Boot, Hibernate, and cloud technologies to create high-performance applications that deliver reliability, flexibility, and long-term business value.
r/JavaProgramming • u/Wide_Second_7767 • 24d ago
What could be off in this my cv for java developer 1+YOE
Can someone give a review of this cv for an entry level/junior java developer