Swing Markdown Renderer

A Swing EditorKit for rendering Markdown inside JEditorPane. Uses commonmark-java to parse Markdown into HTML, which is then displayed through Swing's built-in HTML rendering engine.

Features

• Drop-in EditorKit for any JEditorPane with content type text/markdown
• GFM extensions: tables, strikethrough (~~text~~), and autolinks
• GitHub-inspired default stylesheet (headings, code blocks, blockquotes, tables, etc.)
• Round-trip support: original Markdown source is preserved and written back via write()
• Java 11+

Usage

Dependency

Maven:

<dependency>
    <groupId>ca.weblite</groupId>
    <artifactId>swing-markdown-renderer</artifactId>
    <version>0.1.5</version>
</dependency>

Gradle:

implementation 'ca.weblite:swing-markdown-renderer:0.1.5'

Rendering Markdown

JEditorPane editor = new JEditorPane();
editor.setEditorKit(new MarkdownEditorKit());
editor.setText("# Hello World\nThis is **Markdown**.");

Setting Markdown programmatically

MarkdownEditorKit kit = new MarkdownEditorKit();
editor.setEditorKit(kit);
kit.setMarkdownText(editor, "# Title\nSome *content*.");

Retrieving the original Markdown source

String markdown = MarkdownEditorKit.getMarkdownText(editor);

Converting Markdown to HTML

MarkdownEditorKit kit = new MarkdownEditorKit();
String html = kit.renderToHtml("**bold** and *italic*");

Demo Application

The project includes a live editor demo (MarkdownEditorDemo) with a split pane: type Markdown on the left, see rendered output on the right in real time.

Running the demo

mvn compile exec:java -Dexec.mainClass=ca.weblite.markdown.MarkdownEditorDemo

Or with javac directly:

# Compile
javac -cp "lib/*" -d target/classes src/main/java/ca/weblite/markdown/*.java

# Run
java -cp "lib/*:target/classes" ca.weblite.markdown.MarkdownEditorDemo

Building

Prerequisites

• Java 11 or later
• Maven 3.6+

Build and test

mvn clean test

Package

mvn clean package

The JAR will be in target/swing-markdown-renderer-1.0.0-SNAPSHOT.jar.

Project Structure

src/
  main/java/ca/weblite/markdown/
    MarkdownEditorKit.java      # The EditorKit implementation
    MarkdownEditorDemo.java     # Live preview demo application
  test/java/ca/weblite/markdown/
    MarkdownEditorKitTest.java  # Unit tests (20 tests)

Dependencies

Dependency	Version	Purpose
commonmark	0.21.0	Markdown parser and HTML renderer
commonmark-ext-gfm-tables	0.21.0	GFM table support
commonmark-ext-gfm-strikethrough	0.21.0	GFM strikethrough support
commonmark-ext-autolink	0.21.0	Automatic URL linking
junit	4.13.2	Unit testing (test scope)

License

See LICENSE for details.