Java Roadmap - ashishranjandev/developer-wiki GitHub Wiki
To reach the expertise level of your skip-level manager in Java β particularly in identifying subtle improvements and mastering nuanced decisions (like when to use List vs. Collection) β youβll need a deep and structured learning approach that goes beyond syntax and into system design, performance, and idiomatic usage.
Hereβs a step-by-step roadmap with free, high-quality resources that will help you grow from intermediate to expert level in Java:
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𧱠Phase 1: Solidify Java Fundamentals (if needed)
Even experienced developers benefit from revisiting fundamentals to identify gaps and refine mental models.
Key Areas: β’ Object-Oriented Programming (OOP) β’ Java syntax + core APIs (String, Math, Arrays, List, etc.) β’ Control flow, exceptions, and basic I/O
Resources: β’ π Java Programming by MOOC.fi β Very comprehensive and interactive. β’ π₯ Java Programming - Coursera (Free to audit) by Duke University
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βοΈ Phase 2: Master Collections, Generics & Functional Programming
This is where youβll start distinguishing between good and great Java β knowing when to use List vs Set, Map, Stream, etc.
Key Topics: β’ Java Collections Framework (List, Set, Map, Queue) β’ Generics (bounded types, wildcards) β’ Streams and functional programming (Java 8+) β’ Performance trade-offs in collections
Resources: β’ π Baeldung Collections Guide β Practical, code-heavy guide β’ π₯ Java Collections Framework - freeCodeCamp β’ π Java Generics FAQ β Oracleβs official tutorial
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π Phase 3: Advanced Java Features
Move beyond basic usage into the internals and more niche but powerful Java features.
Key Topics: β’ Concurrency & multithreading β’ Memory management and JVM internals β’ Classloaders, reflection, annotations β’ Design patterns in Java β’ Optional, records, sealed classes (Java 14+)
Resources: β’ π Modern Java - Baeldung β Curated roadmap of articles β’ π₯ Java Memory Management (Java Brains) β’ π The Javaβ’ Tutorials - Oracle β’ π Design Patterns in Java
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π§ Phase 4: Idiomatic & Performance-Critical Java
Develop intuition for whatβs idiomatic, readable, and performant β the kind of expertise your manager likely demonstrates.
Key Topics: β’ Java idioms and anti-patterns β’ Profiling and tuning Java applications β’ Advanced use of Optional, lambdas, and method references β’ When not to use certain collections or abstractions
Resources: β’ π [Effective Java by Joshua Bloch (3rd ed)] β Not free but essential. Look for summaries: β’ π Effective Java Summaries (GitHub) β’ π High-Performance Java (Baeldung) β’ π₯ Java Performance Tuning (Venkat Subramaniam)
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π§βπ¬ Phase 5: Code Reviews, Real Projects & Mentorship
Nothing replaces real-world practice. Start reading great open-source Java code, contribute, or even better, get feedback.
Activities: β’ Contribute to Java OSS projects (e.g., Spring, Apache Commons, etc.) β’ Review GitHub repositories of good Java projects β’ Ask your manager for code review sessions or shadow theirs
Resources: β’ π Open Source Java Projects to Contribute β’ π Code Review Best Practices
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πΊ Bonus: Structured Learning Paths β’ π JetBrains Java Developer Roadmap β PDF map from the creators of IntelliJ. β’ π Exercism.io - Java Track β Practice-focused exercises with mentor feedback.
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ποΈ Month 1: Fundamentals & Core Java Mastery
π Focus: β’ Core Java language features β’ OOP mastery β’ Collections basics β’ Writing clean, idiomatic code
Week 1 β’ π§ MOOC.fi Part 1, Chapters 1β4 β’ π₯ Java OOP Concepts β Java Brains β’ π» Practice: Solve 5 problems on Exercism.io or HackerRank Java Easy
Week 2 β’ π Java Collections β Baeldung Intro β’ π₯ Java Collections in Depth β’ π» Practice: Implement your own ArrayList, LinkedList, and HashMap from scratch
Week 3 β’ π Java Generics β Oracle β’ π§ [Effective Java, Chapter 5 (Generics)] Summary on GitHub β’ π» Practice: Write generic utility classes (e.g., a Pair<T1, T2>)
Week 4 β’ π― Mini project: Build a Task Manager CLI using collections and OOP principles β’ β Peer Review or self-review: Identify unnecessary object creation, poor collection choices
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ποΈ Month 2: Collections, Streams & Functional Java
π Focus: β’ Deep dive into collections and functional programming β’ Stream API mastery β’ Idiomatic Java and lambdas
Week 5 β’ π Java Collections Deep Dive β Baeldung β’ π§ Practice writing HashMap, TreeMap, LinkedHashMap code manually β’ π» Exercise: Build a Word Frequency Counter
Week 6 β’ π₯ Java Streams & Lambdas β Amigoscode β’ π Guide to Stream API β Baeldung β’ π» Practice: Refactor legacy loop-based code to use streams
Week 7 β’ π§ Effective Java β Streams, Lambdas β’ π» Task: Write 3 utility functions using map/filter/reduce β’ Project: Implement a mini ETL pipeline using streams
Week 8 β’ π§ Code review week: Revisit all your past mini-projects β’ π― Identify collection choices, code smells, use of generics β’ Extra: Explore Optional API
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ποΈ Month 3: Advanced Java β Concurrency & JVM
π Focus: β’ Concurrency, multithreading β’ Memory management β’ JVM internals and GC
Week 9 β’ π₯ Java Concurrency Basics β Java Brains β’ π Baeldung on Java Threads β’ π» Practice: Build a thread-safe Counter
Week 10 β’ π₯ Java Memory Model β YouTube β’ π JVM Internals Guide β Baeldung β’ π» Task: Analyze memory with VisualVM
Week 11 β’ π§ Effective Java β Concurrency β’ Project: Build a Multithreaded Web Crawler or file searcher β’ Practice: Use ExecutorService, Callable, Future
Week 12 β’ π Explore: Reflection, Annotations β’ π» Create your own custom annotation & process it with reflection
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ποΈ Month 4: Idiomatic Java, Performance & Architecture
π Focus: β’ Design patterns β’ Performance tuning β’ Clean, idiomatic code β’ Real-world application
Week 13 β’ π Design Patterns in Java β’ π» Implement: Singleton, Factory, Strategy, Observer patterns
Week 14 β’ π Java Performance β Baeldung β’ π₯ Venkat on Performance Tuning β’ π» Profile and optimize your past mini-projects
Week 15 β’ π― Read: High-quality open-source Java code (Spring Boot, Apache Commons) β’ π Google Java Style Guide β’ π» Refactor past code to follow best practices
Week 16 β’ Capstone Project: β’ Build a Spring Boot REST API with clean architecture, DI, concurrency β’ Add logging, input validation, and documentation β’ Share code with mentor or peers for review
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β Additional Tips β’ Join r/Java or Stack Overflow Java tag to stay updated β’ Explore the Java Discord for active mentorship β’ Consider pairing sessions or asking your manager for 1:1 feedback on small snippets
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