This repository contains a collection of real-world Java programming challenges written by Rafael del Nero, the creator of JavaChallengers and a recognized JavaChampion.
Each challenge demonstrates a key Java concept — from generics and pattern matching to concurrency and type systems — explained through concise, executable examples.
They are designed to help developers understand the JVM deeply and reason about Java like professional engineers.
Rafael del Nero is a JavaChampion with over 15 years of software development experience.
He mentors intermediate and senior developers worldwide and is the founder of the JavaChallengers initiative.
He is also a contributing writer at InfoWorld, where his profile contains insightful articles and tutorials exploring practical and advanced Java topics.
These articles are part of the well-known Java Challengers column on InfoWorld, covering real-world language features, JVM behavior, and object-oriented design.
Rafael is the author of:
- Java Challengers
- Java Algorithms Interview Challenger
- Java System Design Interview Challenger
- Golden Lessons
Explore the Java Challengers series on InfoWorld — a collection of sharp, focused articles that explain advanced Java challenges clearly.
Some of Rafael’s most notable articles include:
- Introduction to Java Records: Simplified Data‑Centric Programming
- Basic and Advanced Pattern Matching in Java
- How to Handle Type Erasure in Advanced Generics
- String Comparison and the String Pool
- Thread Behavior in the JVM
For the complete list, visit Rafael del Nero’s InfoWorld author page, which contains all his articles, guides, and Java insights.
RealWorldJavaInterviewQuestionsBook — a free resource for developers preparing for real‑world Java interviews.
👉 Download it free
This guide provides:
- Insights for mid‑ to senior‑level Java developers
- Real technical questions based on hands‑on problem solving
- Career tips for international and remote opportunities
Master every corner of Java through 70+ coding challenges — from inheritance and lambdas to records and concurrency.
Build algorithm and data‑structure mastery directly in Java through real, compilable code challenges.
Gain confidence in system design interviews using Java‑driven examples of scalability, reliability, and architecture trade‑offs.
A 100‑lesson mindset guide for Java developers building clarity, career growth, and remote work opportunities.
Focuses on deep work, communication, LinkedIn presence, and leadership skills.
This repository complements Rafael del Nero’s InfoWorld articles and JavaChallengers books, containing runnable examples that illustrate core principles of the Java platform.
Covered topics include:
- Object orientation (inheritance, polymorphism)
- Generics and type erasure
- Pattern matching and modern Java syntax
- Threading and concurrency
- Streams
- Equality contracts and immutability
Each example is designed for experimentation and learning through practice.
The Java Challengers ecosystem — mentorship, course, books, articles, and challenges — exists to help developers understand Java in depth and communicate their knowledge effectively, both in interviews and professional development.
If you want to read more from Rafael, visit his author page on InfoWorld:
https://www.infoworld.com/profile/rafael-del-nero/