RefactorFirst

This tool for Java codebases will help you identify what you should refactor first:

• God Classes
• Highly Coupled classes
• Class Cycles (with cycle images!)

It scans your Git repository and runs:

• PMD's God Class Rule
• PMD's Coupling Between Objects
• Cycle analysis on your source code using JavaParser and JGraphT

Cycle analysis is performed based on class field types and method signature types at this time (more to come!).

The graphs generated in the report will look similar to this one:

Please Note: Java 11 (or newer) required to run RefactorFirst

The change to require Java 11 is needed to address vulnerability CVE-2023-4759 in JGit
Java 21 codebase analysis is supported!

There are several ways to run the analysis on your codebase:

From The Command Line As an HTML Report

Run the following command from the root of your project (the source code does not need to be built):

mvn org.hjug.refactorfirst.plugin:refactor-first-maven-plugin:0.6.1:htmlReport

View the report at target/site/refactor-first-report.html

As Part of GitHub Actions Output

This will generate a simplified HTML report (no graphs or images) as the output of a GitHub Action step

mvn -B clean test \
org.hjug.refactorfirst.plugin:refactor-first-maven-plugin:0.6.1:simpleHtmlReport \
&& echo "$(cat target/site/refactor-first-report.html)" >> $GITHUB_STEP_SUMMARY

As Part of a Build

Add the following to your project in the build section. showDetails will show God Class metrics and rankings in the generated table.

<build>
    <plugins>
        ...
        <plugin>
            <groupId>org.hjug.refactorfirst.plugin</groupId>
            <artifactId>refactor-first-maven-plugin</artifactId>
            <version>0.6.1</version>       
            <!-- optional -->
            <configuration>
                <showDetails>false</showDetails>
            </configuration>
        </plugin>
        ...
    </plugins>
</build>

As a Maven Report

Add the following to your project in the reports section.
A RefactorFirst report will show up in the site report when you run mvn site

<reporting>
    <plugins>
        ...
        <plugin>
            <groupId>org.hjug.refactorfirst.plugin</groupId>
            <artifactId>refactor-first-maven-plugin</artifactId>
            <version>0.6.1</version>       
        </plugin>
        ...
    </plugins>
</reporting>

If you see an error similar to

 Execution default-site of goal org.apache.maven.plugins:maven-site-plugin:3.3:site failed: A required class was missing while executing org.apache.maven.plugins:maven-site-plugin:3.3:site: org/apache/maven/doxia/siterenderer/DocumentContent

you will need to add the following to your pom.xml:

  <build>
    <plugins>        
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-site-plugin</artifactId>
        <version>3.12.1</version>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-project-info-reports-plugin</artifactId>
        <version>3.4.5</version>
      </plugin>
    </plugins>
  </build>

But I'm using Gradle / my project layout isn't typical!

I would like to create a Gradle plugin and (possibly) support non-conventional projects in the future, but in the meantime you can create a dummy POM file in the same directory as your .git directory:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
 
  <groupId>com.mycompany.app</groupId>
  <artifactId>my-app</artifactId>
  <version>1.0-SNAPSHOT</version>
</project>

and then (assuming Maven is installed) run

mvn org.hjug.refactorfirst.plugin:refactor-first-maven-plugin:0.6.1:htmlReport

Viewing the Report

View the report at target/site/refactor-first-report.html
Once the plugin finishes executing (it may take a while for a large / old codebase), open the file target/site/refactor-first-report.html in the root of the project. It will contain a graph similar to the one above, and a table that lists God classes in the recommended order that they should be refactored. The classes in the top left of the graph are the easiest to refactor while also having the biggest positive impact to team productivity.
If highly coupled classes are detected, a graph and table listing Highly Coupled Classes in will be generated.

I have the report. Now What???

Work with your Product Owner to prioritize the technical debt that has been identified. It may help to explain it as hidden negative value that is slowing team porductivity.
If you have IntelliJ Ultimate, you can install the Method Reference Diagram plugin to help you determine how the identified God classes and Highly Coupled classes can be refactored.

Additional Details

This plugin will work on both single module and multi-module Maven projects that have a typical Maven project layout.

This tool is based on the paper Prioritizing Design Debt Investment Opportunities by Nico Zazworka, Carolyn Seaman, and Forrest Shull. The presentation based on the paper is available at https://resources.sei.cmu.edu/asset_files/Presentation/2011_017_001_516911.pdf

Limitations

• My time. This is a passion project and is developed in my spare time.

Feedback and Collaboration Welcome

There is still much to be done. Your feedback and collaboration would be greatly appreciated in the form of feature requests, bug submissions, and PRs.
If you find this plugin useful, please star this repository and share with your friends & colleagues and on social media.

Future Plans

• Improve class cycle analysis (only field member types and method signature types are currently supported).
• Add a Gradle plugin.
• Incorporate Unit Test coverage metrics to quickly identify the safety of refactoring classes.
• Incorporate bug counts per class to the Impact (Y-Axis) calculation.
• Incorporate more disharmonies from Object Oriented Metrics In Practice (Lanza and Marinescu, 2004).

Note:

If you are a user of Version 0.1.0 or 0.1.1, you may notice that the list of God classes found by the plugin has changed. This is due to changes in PMD.

Thank You! Enjoy!