This blog post explores the collective wisdom found in the famous "97 Things Every Java Programmer Should Know" project, often curated on GitHub and available in PDF formats. The Power of 97
The "97 Things" series by O'Reilly is a goldmine for developers. It isn't a manual on syntax. Instead, it’s a collection of bite-sized wisdom from industry leaders. Why GitHub and PDF versions are popular Community-driven: The GitHub repo allows for updates. Portable learning: PDFs make it easy to read offline. Peer review: High-quality advice vetted by experts. Key Themes to Look For
While you can't memorize all 97, the project generally orbits these vital pillars: 1. Mastering the JVM Understand Garbage Collection (GC) behavior. Learn how the JIT compiler optimizes code.
Don't just write Java; understand the environment it runs in. 2. Clean Code and Readability Programs are read more often than written. Use descriptive naming for variables and methods. Keep methods small and focused on one task. 3. Modern Java Features Embrace Lambdas and Streams. Use Optional to handle nulls safely. Understand the benefits of the newer Module System. 4. Testing and Robustness Unit tests are not optional. Learn to write testable code (Dependency Injection). Handle exceptions gracefully, don't just "swallow" them. 💡 Pro Tip
Don't try to implement all 97 tips at once. Pick three that address your current bottlenecks and master them this week. How to Find the Best Version
Searching GitHub for this title usually leads to repositories containing summary markdown files or links to the official O'Reilly source.
Look for "Stars": High star counts indicate the most reliable repos.
Check the "Issues" tab: See what the community is currently debating.
Verify the License: Ensure the PDF you find is shared legally.
The book 97 Things Every Java Programmer Should Know, edited by Kevlin Henney and Trisha Gee, is a celebrated collection of expert insights designed to elevate a developer's craft from basic syntax to high-level mastery. Unlike standard textbooks, it offers a "wisdom of the crowd" approach, featuring short essays from dozens of industry leaders like Emily Bache, Holly Cummins, and Dave Farley. Core Themes and Key Takeaways 97 things every java programmer should know pdf github
The contributions span technical deep dives, architectural principles, and "soft" professional skills. JVM and Language Nuances:
Garbage Collection is Your Friend: Understanding how GC works helps you write more efficient code rather than fearing it.
Java’s Unspeakable Types: Exploration of complex type system behaviors that often go unnoticed.
Behavior is "Easy"; State is Hard: A fundamental look at why managing application state is the root of most bugs. Modern Engineering Practices:
Learn Your IDE: Reducing cognitive load by mastering tools like IntelliJ IDEA to stay "in the flow".
Test-Driven Development (TDD): Emphasizing the "Red-Green-Refactor" cycle for building reliable software.
Separation of Concerns: Taking modularity seriously to ensure long-term maintainability. Professionalism and Culture:
The Boy Scout Rule: Always leave the code cleaner than you found it.
Don't Just Learn the Language, Understand Its Culture: Understanding the "Java way" of solving problems is as important as the syntax. Top Contributions to Explore All You Need Is Java Anders Norås Garbage Collection Is Your Friend Holly Cummins Learn Your IDE to Reduce Cognitive Load Trisha Gee Test-Driven Development Dave Farley Uncheck Your Exceptions Kevlin Henney This blog post explores the collective wisdom found
97 Things Every Java Programmer Should Know , edited by Kevlin Henney and Trisha Gee, is a collection of brief, expert essays that cover technical and professional wisdom specific to the Java ecosystem. Amazon.com Key Themes and Insights
The book provides a broad perspective on modern Java development, moving beyond basic syntax to architectural and professional standards. Amazon.com JVM & Performance Garbage Collection
: Focuses on viewing GC as a supportive friend rather than an obstacle to manage. JVM Diagnostics
: Tips for understanding the JVM from a performance perspective and how to properly "crash" or debug it. Coding Standards Immutability
: Emphasizes avoiding variable variance and using "Simple Value Objects" to reduce state-related bugs. Naming & Readability
: Advocates for better naming conventions and refactoring specifically for "speed-reading". Idiomatic Java
: Encourages learning and "caching" standard Java idioms to reduce cognitive load. Tooling & Ecosystem IDE Mastery
: Developers should invest time in learning their IDE (like IntelliJ) to stay focused on business logic rather than mechanics. Build Systems
: Highlights that builds should be fast, reliable, and free of "fat JAR" anti-patterns. Modern Features O’Reilly Learning platform – Free trial or access
: Covers staying current with features added since Java 8, such as , Streams, and module declarations. Accessing the Report and Full List
While the full copyrighted text is available through paid platforms like O'Reilly Online Learning
, community-sourced summaries and lists are often found on GitHub and other public repositories. Amazon.com Table of Contents
: A detailed list of all 97 topics and their authors can be viewed on Public Repository : Various "Books to Read" repositories on GitHub, such as Babunashvili's collection
, often host PDF versions or summaries of this and related titles in the series. Gists and Summaries : Search for GitHub Gists
that compile the most critical takeaways for quick reference. of the specific chapters focused on JVM performance 97 Things Every Programmer Should Know - [Henney].pdf
One of the most creative GitHub projects flips the book on its head: "97 Things That Were True in 2011 but Are Misleading in JDK 17+" . Contributors debate outdated advice (e.g., old final performance myths) and update it for modern Java. This is a living document you can contribute to.
While the first edition debuted in 2011, the 2nd edition (2020) covers Java 8, 11, and 12. The lessons on Optional, var, and defensive coding are more relevant than ever.
If you want the real content without piracy:
If you manage to access the content—either via the book or the repository—here are a few staples of the wisdom you will encounter: