google-java-format-hook

A pre-commit hook for automatically formatting only the modified lines of Java files using google-java-format.

Features

• Formats only the changed lines in .java files using google-java-format.
• Automatically downloads and verifies the correct version of the formatter JAR and the official diff script using Python.
• Blocks commits if formatting changes are made, requiring you to review and re-stage.

Requirements

• git
• python3
• pre-commit

Installation

1. Install pre-commit:

   pip install pre-commit
   

2. Add this repo as a hook in your project's .pre-commit-config.yaml:

   - repo: https://github.com/avi-sanwal/google-java-format-hook.git
     rev: main # or the latest release/tag
     hooks:
       - id: google-java-format-hook
   

3. Install the pre-commit hook:

   pre-commit install
   

Usage

On commit, the hook will:

• Download and verify the correct version of google-java-format and the diff script if not present.
• Format only the changed lines in .java files.
• If any files are changed, the commit will be blocked and you will be prompted to review and re-stage the files.
• To get extra logging, set VERBOSE=1 environment variable. E.g. VERBOSE=1 git commit ....

Manual Run

To manually format only the changed lines in .java files, run:

git diff -U0 --no-color | python3 format.py

Customization

• To change the formatter version, edit the VERSION variable in format.py.

Testing

To run tests, ensure you have pytest installed, and then run:

VERBOSE=1 pytest --capture=sys

License

See LICENSE.