A VS Code extension that lets you visually author Eclipse JDT formatter XML profiles with a live before/after Java preview.
Features
Guided Webview Wizard — browse and edit every Eclipse JDT formatter rule through a categorised, searchable UI instead of hand-editing XML.
Live Diff Preview — pick any Java file from your workspace and instantly see an original ↔ formatted side-by-side diff that updates as you change rules.
Full Rule Coverage — supports booleans, enums, numeric values, brace positions, insert options, alignment bit-fields, and more.
Create or Edit — generate a new eclipse-formatter.xml from defaults or open an existing one; the wizard auto-detects formatter documents.
Persistence — preview-file associations are stored per formatter document in workspace state and survive restarts.
Requirements
Java 17+ on PATH (used to run the embedded Eclipse JDT formatter engine).
No additional VS Code extensions are required.
Getting Started
Install the extension (or load the .vsix with Extensions → Install from VSIX…).
Open the Command Palette (Ctrl+Shift+P) and run Eclipse Formatter: Create Formatter XML to scaffold a new profile, or open an existing *formatter*.xml file.
The Formatter Wizard panel opens automatically. Adjust rules in the webview — the underlying XML updates in real time.
Run Eclipse Formatter: Select Preview Java File to choose a .java file, then Eclipse Formatter: Show Formatter Preview to see a live diff.
Commands
Command
Description
Eclipse Formatter: Open Formatter Wizard
Open the wizard panel for the active formatter XML
Eclipse Formatter: Create Formatter XML
Create a new eclipse-formatter.xml in the workspace root
Eclipse Formatter: Select Preview Java File
Pick a Java file to use for before/after preview
Eclipse Formatter: Show Formatter Preview
Show a diff editor comparing original and formatted output
How It Works
The canonical source of truth is a standard Eclipse JDT formatter XML file (<profiles> / <profile> / <setting>).
The webview reads the XML through FormatterXmlService, presents rules grouped by family, and writes changes back into the XML document.
On each change, JavaFormatterBridge invokes the bundled Eclipse JDT formatter (compiled from java-runner/) in a child process to produce formatted output.
A virtual-document content provider serves the formatted text so VS Code's built-in diff editor can display the result.
Development
# Install dependencies
npm install
# Build the Java formatter runner (requires JDK 17+)
npm run build:java-runner
# Watch & compile
npm run watch
# Lint
npm run lint
# Run tests
npm test
# Package as .vsix
npm run package:vsix
Press F5 in VS Code to launch the Extension Development Host with the extension loaded.
License
This project is licensed under the Eclipse Public License 2.0.
See the LICENSE file in the project root for the full license text.
