142 Java Functional Programming

This is a comprehensive refactoring assistant that applies modern Java functional programming patterns to your codebase. It covers the essentials like immutable Records, Streams, and Optional, plus newer features like pattern matching, sealed classes, and Stream Gatherers from Java 21. What makes it solid is the safety-first approach: it won't touch your code unless the project compiles first, and it verifies everything afterward with a full Maven build. The reference material includes good and bad examples for each pattern, so you get concrete guidance on moving side effects to boundaries and keeping your core logic pure. If you're modernizing a Java codebase or just tired of null checks and mutable state, this walks you through the transformation methodically.