Automate Java Code Review with GitHub Actions

Code quality is a vital aspect for any development team. However, performing manual code reviews constantly can be inefficient and prone to human errors or, worse, not reviewing it at all and just settling for it working allows bad practices to persist within the organization. This is where GitHub Actions offers a solution to automate much of the review process, helping to maintain high quality standards without sacrificing efficiency.

In this practical guide, you will learn step by step how to leverage GitHub Actions to implement automatic and effective code reviews on every pull request (PR) and how to configure automated workflows integrating popular static analysis tools and unit tests in your Java project using GitHub Actions. 

You will learn how to integrate tools that analyze code style, detect common errors, identify possible bugs, and measure test coverage, also creating an automated checklist that ensures each PR meets the standards established by your team.

Why automate Java code review?

Automating code review processes offers multiple advantages:

• Consistency: Prevents human errors and ensures that every review follows the same standards.
• Speed: Allows quick detection of common errors before merging into the main branch.
• Efficiency: Frees developers from repetitive tasks to focus on more complex issues.
• Better practices: Accustoms developers to implement good practices in their code on every PR.

Prerequisites before starting

To follow this guide you will need:

• A Java repository hosted on GitHub.
• Java JDK 8 or higher configured in your project.
• Basic familiarity with YAML, Maven, or Gradle.
• Access to create workflows in GitHub Actions.

Configuring GitHub Actions

GitHub Actions workflows are defined in YAML files stored in the .github/workflows folder. Below is the guide with the necessary steps to configure your first workflow.

Step 1️⃣: Create the workflow YAML file

Create the file .github/workflows/ci-java.yml and define the basic structure:

This file configures a basic workflow that triggers on every PR targeting the main branch, but it can also be changed to other branches as needed.

Step 2️⃣: Integrate static analysis with Checkstyle

Checkstyle is a tool that allows you to analyze the source code of your Java files to ensure they comply with certain style rules and conventions defined by the team. 

It does not detect functional errors like a compiler, but aspects such as:

• Whether class, method, or variable names follow a convention (such as camelCase, PascalCase, etc.)
• Whether code blocks are properly indented
• Whether lines are too long
• Whether there are unnecessary spaces or line breaks
• Whether documentation is missing in classes or methods (Javadoc)
• Among other clean code details

To integrate it:

First, in your Maven or Gradle project, add the Checkstyle dependency.

For Maven:

Define the rules in a configuration XML file, for example checkstyle.xml, where you can add rules such as the maximum line length:

Then, add this step in your YAML workflow:

Step 3️⃣: Integrate PMD for advanced detection of defective code

PMD is another powerful static analysis tool to detect potential problems such as:

• Common logic errors
• Bad programming practices
• Duplicated or unnecessary code
• Use of unused variables
• Excessive complexity in methods or classes

To configure it, add the PMD dependency in Maven:

Define the rules in a configuration XML file, for example quickstart.xml, where you can add rules:

Then, add to the workflow:

Step 4️⃣: Detect errors and vulnerabilities with SpotBugs

SpotBugs is an effective tool to detect potential bugs, logic errors, and security vulnerabilities before the code runs. SpotBugs does not analyze the source code directly, but rather analyzes the compiled .class files.

This allows it to perform deeper analysis, including execution flows and bytecode patterns.

To configure it, add the plugin in the pom.xml:

Then, include this step in your workflow:

Step 5️⃣: Integrate code coverage with JaCoCo

JaCoCo measures unit test coverage.

Add it in the pom.xml defining the minimum test coverage percentage:

Then, run the unit tests with coverage from your workflow:

Step 6️⃣: Create an automated checklist

Now that the previous steps are in place, you can create an automated checklist in GitHub Actions using the status checks feature. GitHub will automatically show the results of these steps in the PR interface, indicating whether each automated review passes or fails.

The complete workflow should look like this:

How to interpret and resolve the results📊

When opening a PR, GitHub Actions will automatically run these steps. If any fail, you can access the log directly from GitHub and fix the reported issues before merging the PR. This ensures that only high-quality code reaches the main branches.

‍Best practices and additional recommendations

• Keep your workflow and dependencies up to date.
• Customize Checkstyle and PMD rules according to your needs.
• Encourage your team to pay early attention to automated results to reduce technical debt.

Conclusion

Automating Java code quality with GitHub Actions is an effective strategy to maintain consistency and quality of source code. By adopting these tools and practices, you can quickly detect common problems, significantly reduce manual effort, and greatly improve team efficiency.

Start today to implement these robust automated processes and take your Java project’s productivity and reliability to the next level.

Does your team still review code manually or overlook errors in production?
👉 Contact us and we’ll help you implement a robust and automated CI strategy with GitHub Actions for your Java projects.