Marklet

Marklet is a Doclet that plugs into javadoc. The purpose of Marklet is to generate Javadoc in Markdown format instead of the usual HTML that javadoc creates. This version requires Java 14 or higher to run, but can document all lower source code versions.

Currently working on the migration from com.sun.javadoc to the newer jdk.javadoc.doclet API because the older classes are no longer supported on Java 12 and up. Still work in progress.

Examples :

• Marklet documenting itself!

How to use

You can run Marklet on the command line to generate one-shot documentation or add it to your pom.xml so Markdown docs are created on Maven build. You probably can use it from Gradle, but since I am a Maven guy, I don't know the syntax.

The most important caveat is that you have to specify the Java packages (option -subpackage) you want to document and their location in the file system (option -sourcepath) correctly, otherwise no output will be generated (specifying -sourcepath alone is not sufficient).

Command-line use

First run mvn package to build the doclet.

Linux/macOS:

javadoc -docletpath ./target/marklet-2.0.0.jar \
  -doclet io.github.atlascommunity.marklet.Marklet \
  -cp ./target/marklet-2.0.0.jar \
  -sourcepath ./src/main/java \
  -subpackages io.github.atlascommunity.marklet

Windows:

javadoc -docletpath .\target\marklet-2.0.0.jar  -doclet io.github.atlascommunity.marklet.Marklet -cp .\target\marklet-2.0.0.jar -sourcepath .\src\main\java -subpackages io.github.atlascommunity.marklet

On both platforms, be sure to set subpackages toyour project packages qualified name and sourcepath pointing to your sources.

Maven use

In order to use it with Maven, add the following configuration for the maven-javadoc-plugin in your project POM :

<profiles>
    <profile>
        <id>generate-markdown</id>
        <activation>
            <activeByDefault>false</activeByDefault>
        </activation>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-javadoc-plugin</artifactId>
                    <version>${maven-javadoc-plugin.version}</version>
                    <configuration>
                        <doclet>io.github.atlascommunity.marklet.Marklet</doclet>
                        <docletArtifact>
                            <groupId>io.github.atlascommunity</groupId>
                            <artifactId>marklet</artifactId>
                            <version>2.0.0</version>
                        </docletArtifact>
                        <reportOutputDirectory>./</reportOutputDirectory>
                        <destDir>./</destDir>
                        <useStandardDocletOptions>false</useStandardDocletOptions>
                        <additionalOptions>
                            <additionalOption>-e markdown</additionalOption>
                        </additionalOptions>
                        <show>private</show>
                        <subpackages>io.github.atlascommunity.marklet</subpackages>
                        <sourcepath>src/main/java/</sourcepath>
                    </configuration>
                </plugin>
            </plugins>
        </build>
    </profile>
</profiles>

This profile is not active by default, so the Markdown documentation would not get re-created with each Maven run, but if you type mvn clean package -P generate-markdown, it gets run. If you want to have it permanently active, set activeByDefault to true:

<activation>
     <activeByDefault>true</activeByDefault>
 </activation>

Running from Maven, you may omit the sourcepath option, but be sure to set subpackages to your project packages qualified name. You may usually omit reportOutputDirectory, but not destDir.

If you set show to public, no internals (protected/private objects) will be documented, and your api-docs will be the public API.

useStandardDocletOptions interferes with the working of Marklet, it must be set to false.

This will generate the javadoc report into the project directory under project subfolder javadoc and use the file extension .markdown ( the -e in the additionalOptions overrides the default extension .md).

The Apache Maven site has more information on how to use alternate doclets like Marklet in addition to the default HTML-generating javadoc-plugin.

Java 8 doclint issues.

If you are using Java 8 you may have some issues with doclint validation especially when using Markdown blockquotes syntax. To deal with it, just add the following directive to your pom.xml file to deactivate doclint :

<additionalOptions>
    <additionalOption>-Xdoclint:none</additionalOption>
</additionalOptions>

Available doclet options

Option	LongOpt	What it does	By default
-e		set files extension	.md
-i		location of the source directory
-d	-destDir	location of the target output directory	.javadoc/

Developing Marklet

To hack on Marklet and improve it, look at Marklet.java and use the main() method to get it to run in any IDE. The provided options allow you to run Marklet on its own source tree.

In order to generate Markdown documentation for Marklet itself via Maven, run

$ mvn -P generate-markdown javadoc:javadoc

Developer docs

• new jdk.javadoc.doclet API Docs
• Javadoc for jdk.javadoc.doclet

License

Marklet is licensed under the Apache License, Version 2.0

Current issues

The current version is still under development with the following issues:

• Interfaces, inner classes, enumerations, and annotations might have bugs.

• read https://stackoverflow.com/questions/5592703/documented-annotation-in-java

• Many modern (post Java-8) features will not be documented yet.

• Migration from com.sun.javadoc to jdk.javadoc.doclet API (WIP)

• Basically no unit tests