🚀 Java Core Mastery

A structured repository focused on deepening and systematizing core Java concepts — emphasizing clarity, correctness, and practical understanding.

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🧠 Purpose of This Repository

This is NOT a project repository.

This repository exists to:

• Build deep understanding of core Java concepts
• Organize knowledge in a structured and progressive way
• Serve as a personal reference + interview preparation system

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⚠️ What This Repository Is NOT

To maintain clarity and focus:

❌ This is NOT a place for full-fledged applications ❌ This is NOT for system design projects (e.g., Rate Limiter, Cache, etc.) ❌ This is NOT a dumping ground for random code

👉 Such projects belong in separate repositories

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🏗️ Repository Structure

java-core-mastery/
├── 01-functional-programming/
├── 02-collections-and-generics/
├── 03-concurrency-basics/
├── 04-exception-handling/
├── 05-file-io-and-nio/
├── 06-jvm-memory-basics/
├── 07-modern-java-features/

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📚 Current Coverage

1️⃣ Functional Programming

• Lambda expressions
• Functional interfaces (Predicate, Function, Consumer, etc.)
• Streams API (map, filter, reduce)
• Method references
• Parallel streams

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2️⃣ Collections & Generics

• List, Set, Map implementations
• Sorting (Comparable vs Comparator)
• Concurrent collections (ConcurrentHashMap, CopyOnWriteArrayList)
• Generics and type safety

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🚧 Planned Modules (Future Roadmap)

This repository will evolve to include:

🔹 Concurrency Basics

• Thread creation (Thread vs Runnable)
• Synchronization and locks
• ExecutorService and thread pools
• Atomic variables and race conditions

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🔹 Exception Handling

• Checked vs unchecked exceptions
• Custom exceptions
• Best practices and anti-patterns

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🔹 File I/O & NIO

• File reading/writing
• Buffered streams
• NIO APIs (Files, Paths)

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🔹 JVM Memory Basics

• Heap vs Stack
• Object lifecycle
• Garbage collection basics
• String pool and intern()

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🔹 Modern Java Features

• var keyword
• Records
• Sealed classes
• Switch expressions

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🧭 Design Philosophy

This repository follows:

• 📌 Concept-first approach (not project-first)
• 📌 Small, focused examples instead of large codebases
• 📌 Clarity over complexity
• 📌 Progressive learning structure

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🔗 Related Projects (Real-World Applications)

For system-level implementations using these concepts:

• 💳 Payment Plugin System
• 🧵 Task Processing System (planned)
• 🗄️ In-Memory Cache (planned)
• 🚦 Rate Limiter (planned)

👉 These are maintained as separate repositories

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🎯 Goal

To build a strong foundation in Java such that:

• Core concepts are intuitive
• Interview questions can be answered with clarity and depth
• Real-world systems can be built on top of solid fundamentals

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⚡ Final Note

If you're exploring this repository:

Think of it as a well-organized knowledge base, not a collection of projects.

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