Java Tutorials and Learning Guides
Use these tutorials to understand a topic, then follow the included links to practice it.
Latest Java guides
- Java Roadmap 2026: Beginner-to-Job-Ready Learning Path — A practical Java learning path from syntax and debugging through OOP, collections, testing, databases, and a portfolio project, with exercises for each stage.
- Java vs Python in 2026: Which Should a Beginner Learn First? — A goal-based Java and Python comparison for beginners covering type systems, feedback, tooling, deployment, and a fair hands-on decision exercise.
- How to Learn DSA in Java: A Practical 2026 Guide — Learn DSA in Java through invariants and reusable patterns, with a staged practice order, a tested example, review method, and complexity checklist.
- Top 50 Java Interview Questions for 2026 (with Answers) — Fifty concise Java interview questions with accurate answers across language basics, OOP, collections, exceptions, concurrency, the JVM, and practical coding.
- 10 Mistakes Every Java Beginner Makes (and How to Fix Them) — Ten common Java mistakes explained with causes, fixes, boundary cases, and a tested program that demonstrates value equality and integer division.
- Java Arrays — Complete Tutorial with 15 Practice Problems — Learn Java arrays through traversal, bounds, in-place updates, 2D arrays, copying, complexity, common mistakes, and 15 linked practice problems.
- Java Two Pointers: When It Works, Why It Works, and Practice — Learn the Java two-pointer pattern for sorted arrays, reversals, palindromes, and container problems, with invariants, edge cases, and practice links.
- Java StringBuilder: Build Text Efficiently Without Losing Clarity — Understand Java String immutability, StringBuilder, capacity, and safe text-building patterns with runnable examples and practice exercises.
- Java Encapsulation: Protect State with Small, Useful Methods — A practical Java encapsulation guide covering constructors, invariants, getters, behavior methods, and when public setters are harmful.
- Choosing Java Collections: List, Set, Map, Queue, and Deque — Choose Java collections by the operation you need, not by habit: practical guidance for List, Set, Map, Queue, Deque, and ordered variants.
- Java HashMap Patterns: Counts, Complements, and Grouping — Use Java HashMap deliberately for frequency counts, two-sum complements, grouping, and first-seen index patterns with pitfalls and exercises.
- Sliding Window in Java: Fixed Windows, Variable Windows, and Deques — Learn Java sliding-window reasoning for fixed-size totals, variable constraints, and monotonic deque maximums with examples and next exercises.
- Reading Java Compiler Errors: A Repeatable Debugging Routine — Learn a calm, repeatable routine for Java compiler errors, runtime exceptions, wrong output, and minimal reproduction in the online compiler.
- Testing Small Java Methods: Contracts, Boundaries, and Evidence — Write testable Java methods by stating contracts, choosing boundary cases, and separating calculation from console output.