Java Runtime Configurator

A Visual Studio Code extension that helps you discover Java runtimes and add them to the VS Code Java runtime configuration.

Requirements

• VS Code 1.100 or newer
• The Java extension reads and uses java.configuration.runtimes
• Access to the local filesystem where JDKs or JREs are installed

Command

• Java Runtimes: Scan Folders and Configure

What It Does

• Prompts for one or more root folders.
• Scans recursively for Java installations.
• Uses the runtime root folder name as the name value.
• If the folder name does not contain the detected Java version, appends _<version>.
• Adds discovered Java homes to the java.configuration.runtimes setting.
• Adds sources and javadoc when those paths are detected.
• Prompts for which runtime should be the default for the current workspace and stores it in workspace settings.

How It Works

1. Run the command from the Command Palette.
2. Select one or more root folders to scan.
3. The extension searches recursively for directories that contain bin/java or bin/java.exe.
4. If javac is present, the runtime is treated as a JDK; otherwise it is treated as a JRE.
5. New runtimes are appended to java.configuration.runtimes in user settings.
6. You are prompted to choose which runtime should be the default for the current workspace.

Runtime Naming Rules

• The runtime name starts with the Java home folder name.
• If the detected Java version is already contained in the folder name, the folder name is used as-is.
• If the version is missing from the folder name, the extension appends _<version>.
• If sources or javadoc are found, they are added to the runtime entry.

Example Workflow

1. Open the Command Palette.
2. Run Java Runtimes: Scan Folders and Configure.
3. Select a folder such as /usr/lib/jvm or C:\Java.
4. Review the detected runtimes.
5. Choose the default runtime for the current workspace when prompted.

Example Runtime Entry

"java.configuration.runtimes": [
	{
		"name": "java-18-openjdk",
		"path": "/usr/lib/jvm/java-18-openjdk",
		"sources": "/usr/lib/jvm/java-18-openjdk/lib/src.zip",
		"javadoc": "/usr/share/javadoc/java-18-openjdk/api",
		"default": true
	}
]

Limitations

• The extension is intended for local filesystem runtimes.
• Virtual workspaces are not supported.
• Existing runtime entries are preserved and not rewritten unless the same path is newly added.

Development

• Install dependencies: npm install
• Build: npm run compile
• Run tests: npm test
• Package VSIX: npm run package

Testing

The repository includes a VS Code extension test runner based on @vscode/test-electron and Mocha. The test suite validates command registration and the runtime naming/version helper logic.

Troubleshooting

• If no runtimes are found, verify the selected directory contains JDK or JRE installations with bin/java.
• If sources or javadoc are missing, verify the runtime installation includes lib/src.zip, docs/api, javadoc/api, or a matching shared javadoc directory.
• If packaging fails, run npm run compile first and confirm the repository is in a packageable state.

License

EPL-2.0