Modernizing Java applications with GitHub Copilot

The GitHub Copilot app modernization extension in Visual Studio Code automates Java upgrades by identifying outdated frameworks, deprecated APIs, and upgrade blockers. Copilot コーディング エージェント applies code changes, updates build files, and resolves build and CVE issues for you.

The recommendations and reporting produced by the extension can help your teams adopt new technologies quickly and reduce technical debt. Copilot guides you through upgrades with actionable steps and summaries, accelerating and securing your migrations while reducing manual effort.

For extension capabilities, setup, and user interface instructions, see The GitHub Copilot app modernization documentation in the Microsoft documentation.

Modernization framework

When you start an agent session using the Java upgrade extension, the extension will help you modernize your Java application using the following framework.

• Perform assessment tasks. The extension can analyze code, configuration, and dependencies, providing an assessment of your application's current state.
• Create a customizable modernization plan. Based on the assessment, the extension can suggest a modernization path, including necessary framework and library updates.
• Early identification of issues. The extension identifies dependencies, outdated libraries and language features, and potential migration issues. The extension provides actionable strategies to remediate problems.
• Customize your plan. Edit the modernization plan to your application's specific needs, such as incorporating organizational standards and practices, excluding certain components, or prioritizing specific features or design patterns.
• Implement your plan. The extension can assist in applying code changes, updating build files, refactoring deprecated APIs, and resolving build and syntax issues. The extension will automatically fix build errors and perform test validations after each step to ensure stability and error-free changes.
• Review your changes. The extension can produce a detailed upgrade report, summarizing the changes applied, and listing any unaddressed issues and remaining steps for your modernization.
• Generate unit tests. The extension automatically evaluates existing tests, and generates new test files and adds them to the workspace. A report is produced summarizing the pre- and post-generation test results.
• Containerize your application. The extension can automatically generate Dockerfiles, build images, and validate everything for your modernized application to run within the container services such as Azure Kubernetes Service (AKS), Azure Container Apps (ACA), and AKS Automatic, enabling easier deployment and scalability.
• Prepare for deployment. The extension can help you prepare your application for containerization and deployment, by generating deployment artifacts such as scripts and configurations.
• Automate deployment to Azure. The extension can help you deploy or provision your modernized application to Azure, generating necessary artifacts and Azure resources, and performing execution steps.

You can improve your team's understanding of the application codebase, and save time and effort by using Copilot to help with complex modernization tasks such as:

• Reverse engineering and code transformation
• Vulnerability and dependency analysis, and code behavior checks and remediation
• Automated generation of assets, documentation, and upgrade reports
• Test generation and evaluation
• Deployment automation

Modernization workflow overview

In this example, we'll walk through the high-level steps to modernize a Java application using the GitHub Copilot app modernization extension in Visual Studio Code.

For detailed prerequisites and instructions, see Quickstart: upgrade a Java project with GitHub Copilot app modernization in the Microsoft documentation.

1. Open your Java project

Use VS Code to open your project folder.

Suggested actions

• Ensure your project builds successfully before proceeding.
• If you encounter build issues, you can use Copilot to help resolve them before starting the modernization process.

2. Start a modernization workspace

Launch Copilot チャット and start a new session in agent mode. Choose GitHub Copilot app modernization – upgrade for Java from the available tools.

3. Analyze your project for upgrade opportunities

Copilot will scan your codebase. The analysis includes:

• Detection of outdated frameworks (for example, Spring Boot, Jakarta EE, Java SE versions).
• Identification of deprecated APIs and obsolete patterns.
• Suggestions for upgrade opportunities.

You can review the findings and a structured upgrade plan in the editor, which will display:

• Current and recommended versions for frameworks and dependencies.
• Code locations requiring migration or refactoring.
• Upgrade blockers or incompatible dependencies.

Suggested actions

• Review and customize the modernization plan before proceeding with the upgrade.

4. Apply Copilot upgrade recommendations

Use Copilot to apply or review code changes, update build files, and refactor APIs.

If build errors are found, Copilot can enter a fix-and-test loop until the project compiles cleanly.

Copilot コーディング エージェント automated changes can include:

• Updating pom.xml or build.gradle files for new dependency versions.
• Generating pull requests or committing changes directly.
• Refactoring code for API changes. For example, migrating from javax.* to jakarta.* namespaces.
• Suggesting or applying code transformations to address breaking changes.

Copilot will iterate and continue to fix errors until the project builds successfully and there are no more issues that require fixing. It's possible that minor issues that don't require immediate fixes may remain. These will not prevent the upgrade from completing.

Suggested actions

• Review all code changes in your diff editor before accepting.
• Use Copilot to further explain and document code changes.
• When the extension prompts you to, accept the options to check modified dependencies for known CVEs, and to validate code behavior for consistency.
• Review any issues remaining and evaluate their importance.

5. View the upgrade report and suggested next steps

After the upgrade process is complete, Copilot will generate a summary upgrade report that includes:

• Project information.
• Lines of code changed.
• Updated dependencies.
• Summarized code changes.
• Fixed CVE security and code inconsistency issues, if any.
• Unaddressed minor CVE issues.

Suggested actions

• Review the report to understand the changes made.
• Follow any suggested next steps to finalize your modernization.

Completing the modernization

Further work to support your modernization may include:

• Checking the initial modernization and code changes thoroughly. Ensure your company's coding standards and best practices are met.
• Reviewing modified code closely. For example, check that the generated code fits the purpose and architecture of your project. For more suggestions, see AI によって生成されたコードを確認する.
• Bug fixing. Check specific content for subtle errors, and use your own debugging and linting tools to evaluate new content.
• Writing tests and identifying gaps in testing for the upgraded project.
• Cleaning up the project by removing any files that are no longer needed.
• Refactoring the code in the new language. The modernization process may have resulted in a project whose architecture was based on that of your original project, but that is no longer the ideal or optimum solution for your needs. You may now want to refactor the code to make best use of features of the language and the framework used.
• Updating documentation. Your project information and contributing files may now be out of date and need to be rewritten.
• Containerization. Update your application code, generate containerization files like Dockerfiles, and build the image to test the validity. If needed, Copilot can perform these containerization tasks, and also create a comprehensive plan detailing the next steps.
• Deploying the modernized application to your target environments, including cloud platforms such as Microsoft Azure.