Java Distiller

Java Distiller

Transform Java code into its cleanest, most modern, idiomatic form. Distill away verbosity, legacy patterns, and accidental complexity — keep only the essence.

Philosophy

• Distill, don't decorate — remove complexity, don't add abstractions
• Modern Java first — use Java 21+ features wherever they simplify the code
• Functional over imperative — prefer streams, lambdas, and declarative style when clearer
• Less code, more meaning — every remaining line should earn its place
• Preserve exact behavior — distilling is refactoring, not rewriting

Workflow

1. Read the input code carefully
2. Identify transformation opportunities (see references/transformations.md)
3. Apply transformations — prioritize those with the highest impact-to-risk ratio
4. Present the distilled code with a brief explanation of what changed and why

Transformation Priority

Apply in this order — high-impact, low-risk first:

1. Syntax modernization — var, text blocks, switch expressions, pattern matching, module imports
2. API upgrades — java.time, java.nio.file, HttpClient, List.of/Map.of, Optional, Stream
3. Pattern adoption — records, sealed interfaces, pattern matching for instanceof and switch
4. Functional style — streams over loops, lambdas over anonymous classes, method references
5. Concurrency modernization — virtual threads, structured concurrency, scoped values (only when the codebase already uses them or the target JDK supports them)
6. Structural simplification — flatten hierarchies, inline trivial methods, remove dead code

Output Format

## Distilled Java Code

```java
// transformed code
```

### Changes
- <what changed> — <why it's better>
- ...

Rules

• Preserve behavior exactly — distilling is refactoring, not rewriting
• Do not add comments, Javadoc, or logging that wasn't there
• Do not add error handling beyond what exists unless the original code has a bug
• Do not introduce new dependencies
• Remove unnecessary blank lines, redundant modifiers, and dead imports
• Use var where the type is obvious from the right-hand side
• Use module imports (import module java.net.http;) over individual type imports when the target JDK supports them
• Prefer void main() over public static void main(String[] args) when appropriate
• When multiple transformations compete, choose the one that produces fewer lines
• If the code is already clean and modern, say so — don't force changes
• Respect the project's target Java version; do not introduce preview features unless explicitly enabled

Detailed Transformation Catalog

See references/transformations.md for the complete catalog of before/after transformation patterns organized by category.