pre-commit hooks for Java tools

This repository contains pre-commit hooks for running tools that require a Java Virtual Machine to run.

(The tools may be applicable to languages other than Java.)

These hooks use cjdk to download and cache both the JVM and the tool packages, so that there is no need for java to be available on the PATH or for JAVA_HOME to be configured correctly for the tools. You can run the hooks using a different JDK from your JAVA_HOME.

Available hooks:

• checkstyle - run Checkstyle
• pmd - run the PMD static analyzer
• cpd - run PMD's CPD (copy-paste detector)
• google-java-format - run google-java-format

Requirements

Python >= 3.8; pre-commit >= 2.0.0.

checkstyle

Runs Checkstyle on Java source files.

Arguments:

• --jdk=temruin-jre:17: set the JDK or JRE to use, using cjdk syntax
• --tool-version=10.3.1: set the Checkstyle version to use
• --jvm-arg=<arg>: any argument to pass to java (can be given multiple times)
• --: pass all subsequent arguments to Checkstyle

See also: Checkstyle command line usage.

If you override args, you need to include the -c option.

By default, the "Sun" style checks (/sun_checks.xml) included with Checkstyle are used.

.pre-commit-config.yaml examples:

- repo: https://github.com/cachedjdk/cjdk-pre-commit
  rev: v0.1.0
  hooks:
    - id: checkstyle
      args: ["-c", "/google_checks.xml"]
      verbose: true  # /google_checks.xml only issues warnings.

- repo: https://github.com/cachedjdk/cjdk-pre-commit
  rev: v0.1.0
  hooks:
    - id: checkstyle
      args:
        - --jdk=temurin-jre:17.0.3
        - --tool-version=10.3.1
        - --jvm-arg=-Xmx2048M
        - --
        - -c
        - /sun_checks.xml

pmd

Runs the PMD static code analyzer on source files (Java source files by default).

Arguments:

• --jdk=temurin-jre:17: set the JDK or JRE to use, using cjdk syntax
• --tool-version=6.47.0: set the PMD version to use
• --jvm-args="<args>": set PMD_JAVA_OPTS to <args>
• --: pass all subsequent arguments to PMD's command-line interface

See also: PMD command line usage and reference.

If you override args, you need to include the -R and -d options.

By default, the rulesets/java/quickstart.xml ruleset is run on the directory src/main/java.

.pre-commit-config.yaml example:

- repo: https://github.com/cachedjdk/cjdk-pre-commit
  rev: v0.1.0
  hooks:
    - id: pmd
      args:
        - --
        - -R
        - my_ruleset.xml
        - -d
        - src/main/java

cpd

Runs PMD's copy-paste detector CPD on source files (Java source files by default).

Arguments:

• --jdk=temurin-jre:17: set the JDK or JRE to use, using cjdk syntax
• --tool-version=6.47.0: set the PMD version to use
• --jvm-args="<args>": set PMD_JAVA_OPTS to <args>
• --: pass all subsequent arguments to CPD's command-line interface

See also: CPD command line usage and reference.

If you override args, you need to include the --minimum-tokens and --files options.

By default, the minimum token count is set to 100 and CPD is run on the files in src/main/java.

.pre-commit-config.yaml example:

- repo: https://github.com/cachedjdk/cjdk-pre-commit
  rev: v0.1.0
  hooks:
    - id: cpd

.pre-commit-config.yaml example for running CPD on Python source files:

- repo: https://github.com/cachedjdk/cjdk-pre-commit
  rev: v0.1.0
  hooks:
    - id: cpd
      types: [python]
      args:
        - --
        - --language
        - python
        - --minimum-tokens
        - "100"
        - --files
        - src

google-java-format

Formats Java source files using google-java-format.

Arguments:

• --jdk=temruin:17: set the JDK to use, using cjdk syntax
• --tool-version=1.15.0: set the google-java-format version to use
• --jvm-arg=<arg>: any argument to pass to java (can be given multiple times)
• --: pass all subsequent arguments to google-java-format

See also: google-java-format command line usage, produced by running cjdk_pre_commit google-java-format -- --help.

Note that google-java-format requires a full JDK and will not run with a JRE.

If you override args, you will probably want to include --replace.

.pre-commit-config.yaml example:

- repo: https://github.com/cachedjdk/cjdk-pre-commit
  rev: v0.1.0
  hooks:
    - id: google-java-format
      args:
        - --
        - --replace
        - --skip-reflowing-long-strings

Development

git clone https://github.com/cachedjdk/cjdk-pre-commit.git
cd cjdk-pre-commit
python -m venv venv
echo '*' >venv/.gitignore
source venv/bin/activate
pip install -e .[dev,testing]
pre-commit install

Run unit tests:

pytest

Run system tests:

pytest systemtests

Run tests as done by the CI:

nox
nox -s systemtest

Changelog

0.1.0 - 2022-07-12

• First release.