python-to-java

name

python-to-java

description

Convert Python scripts to zero-dependency Java 25 CLI programs. Use when asked to migrate, convert, port, or rewrite Python scripts (.py) to Java, or when translating a Python codebase to Java CLI scripts or apps. Triggers on "convert Python to Java", "migrate Python", "port to Java", "rewrite in Java", or when a .py file is presented with instructions to produce a Java equivalent. Prefer /java-cli-script for single-file scripts; switch to /java-cli-app when shared code duplication across scripts exceeds ~100 lines.

Python to Java Migration

Convert Python scripts to idiomatic Java 25 CLI programs with zero external dependencies.

Decision: Single-File vs Multi-File

Evaluate before writing any code:

1. Start with /java-cli-script — one Java file per Python script, no build tool
2. Switch to /java-cli-app when any of these apply:
   • Multiple scripts share >100 lines of identical code (e.g. domain records)
   • A single script exceeds ~500 lines
   • Scripts import from each other in Python (from module import func)

When switching to /java-cli-app, extract shared code into common source files within the multi-file project.

Migration Process

1. Read all Python scripts — understand dependencies between them (import graph)
2. Identify shared code — utils.py, common helpers, shared data classes
3. Decide single-file vs multi-file per the rules above
4. Translate each script using the idiom mapping below
5. Verify — run each script with -version to confirm compilation

Python to Java 25 Idiom Mapping

See references/idiom-mapping.md for the complete translation table covering argument parsing, file I/O, subprocess management, concurrency, and standard library equivalents.