Gradle
To generate documentation for a Gradle-based project, you can use the Gradle plugin for Dokka.
It comes with basic autoconfiguration for your project, has convenient Gradle tasks for generating documentation, and provides a great deal of configuration options to customize the output.
You can play around with Dokka and see how it can be configured for various projects by visiting our Gradle example projects.
Apply Dokka
The recommended way of applying the Gradle plugin for Dokka is with the plugins DSL:
When documenting multi-project builds, you need to apply the Gradle plugin for Dokka within subprojects as well. You can use allprojects {}
or subprojects {}
Gradle configurations to achieve that:
See Configuration examples if you are not sure where to apply Dokka.
If you cannot use the plugins DSL for some reason, you can use the legacy method of applying plugins.
Generate documentation
The Gradle plugin for Dokka comes with HTML, Markdown and Javadoc output formats built in. It adds a number of tasks for generating documentation, both for single and multi-project builds.
Single-project builds
Use the following tasks to build documentation for simple, single-project applications and libraries:
Task | Description |
---|---|
| Generates documentation in HTML format. |
Experimental formats
Task | Description |
---|---|
| Generates documentation in GitHub Flavored Markdown format. |
| Generates documentation in Javadoc format. |
| Generates documentation in Jekyll compatible Markdown format. |
By default, generated documentation is located in the build/dokka/{format}
directory of your project. The output location, among other things, can be configured.
Multi-project builds
For documenting multi-project builds, make sure that you apply the Gradle plugin for Dokka within subprojects that you want to generate documentation for, as well as in their parent project.
MultiModule tasks
MultiModule
tasks generate documentation for each subproject individually via Partial
tasks, collect and process all outputs, and produce complete documentation with a common table of contents and resolved cross-project references.
Dokka creates the following tasks for parent projects automatically:
Task | Description |
---|---|
| Generates multi-module documentation in HTML output format. |
Experimental formats (multi-module)
Task | Description |
---|---|
| Generates multi-module documentation in GitHub Flavored Markdown output format. |
| Generates multi-module documentation in Jekyll compatible Markdown output format. |
By default, you can find ready-to-use documentation under {parentProject}/build/dokka/{format}MultiModule
directory.
MultiModule results
Given a project with the following structure:
These pages are generated after running dokkaHtmlMultiModule
:
See our multi-module project example for more details.
Collector tasks
Similar to MultiModule
tasks, Collector
tasks are created for each parent project: dokkaHtmlCollector
, dokkaGfmCollector
, dokkaJavadocCollector
and dokkaJekyllCollector
.
A Collector
task executes the corresponding single-project task for each subproject (for example, dokkaHtml
), and merges all outputs into a single virtual project.
The resulting documentation looks as if you have a single-project build that contains all declarations from the subprojects.
Collector results
Given a project with the following structure:
These pages are generated after running dokkaHtmlCollector
:
See our multi-module project example for more details.
Partial tasks
Each subproject has Partial
tasks created for it: dokkaHtmlPartial
, dokkaGfmPartial
, and dokkaJekyllPartial
.
These tasks are not intended to be run independently, they are called by the parent's MultiModule task.
However, you can configure Partial
tasks to customize Dokka for your subprojects.
Build javadoc.jar
If you want to publish your library to a repository, you may need to provide a javadoc.jar
file that contains API reference documentation of your library.
For example, if you want to publish to Maven Central, you must supply a javadoc.jar
alongside your project. However, not all repositories have that rule.
The Gradle plugin for Dokka does not provide any way to do this out of the box, but it can be achieved with custom Gradle tasks. One for generating documentation in HTML format and another one for Javadoc format:
Configuration examples
Depending on the type of project that you have, the way you apply and configure Dokka differs slightly. However, configuration options themselves are the same, regardless of the type of your project.
For simple and flat projects with a single build.gradle.kts
or build.gradle
file found in the root of your project, see Single-project configuration.
For a more complex build with subprojects and multiple nested build.gradle.kts
or build.gradle
files, see Multi-project configuration.
Single-project configuration
Single-project builds usually have only one build.gradle.kts
or build.gradle
file in the root of the project, and typically have the following structure:
Single platform:
Multiplatform:
Single platform:
Multiplatform:
In such projects, you need to apply Dokka and its configuration in the root build.gradle.kts
or build.gradle
file.
You can configure tasks and output formats individually:
Inside ./build.gradle.kts
:
Inside ./build.gradle
:
Or you can configure all tasks and output formats at the same time:
Inside ./build.gradle.kts
:
Inside ./build.gradle
:
Multi-project configuration
Gradle's multi-project builds are more complex in structure and configuration. They usually have multiple nested build.gradle.kts
or build.gradle
files, and typically have the following structure:
In this case, there are multiple ways of applying and configuring Dokka.
Subproject configuration
To configure subprojects in a multi-project build, you need to configure Partial
tasks.
You can configure all subprojects at the same time in the root build.gradle.kts
or build.gradle
file, using Gradle's allprojects {}
or subprojects {}
configuration blocks:
In the root ./build.gradle.kts
:
In the root ./build.gradle
:
Alternatively, you can apply and configure Dokka within subprojects individually.
For example, to have specific settings for the subproject-A
subproject only, you need to apply the following code inside ./subproject-A/build.gradle.kts
:
Inside ./subproject-A/build.gradle.kts
:
Inside ./subproject-A/build.gradle
:
Parent project configuration
If you want to configure something which is universal across all documentation and does not belong to the subprojects - in other words, it's a property of the parent project - you need to configure the MultiModule
tasks.
For example, if you want to change the name of your project which is used in the header of the HTML documentation, you need to apply the following inside the root build.gradle.kts
or build.gradle
file:
In the root ./build.gradle.kts
file:
In the root ./build.gradle
file:
Configuration options
Dokka has many configuration options to tailor your and your reader's experience.
Below are some examples and detailed descriptions for each configuration section. You can also find an example with all configuration options applied at the bottom of the page.
See Configuration examples for more details on where to apply configuration blocks and how.
General configuration
Here is an example of general configuration of any Dokka task, regardless of source set or package:
- moduleName
The display name used to refer to the module. It is used for the table of contents, navigation, logging, etc.
If set for a single-project build or a
MultiModule
task, it is used as the project name.Default: Gradle project name
- moduleVersion
The module version. If set for a single-project build or a
MultiModule
task, it is used as the project version.Default: Gradle project version
- outputDirectory
The directory to where documentation is generated, regardless of format. It can be set on a per-task basis.
The default is
{project}/{buildDir}/{format}
, where{format}
is the task name with the "dokka" prefix removed. For thedokkaHtmlMultiModule
task, it isproject/buildDir/htmlMultiModule
.- failOnWarning
Whether to fail documentation generation if Dokka has emitted a warning or an error. The process waits until all errors and warnings have been emitted first.
This setting works well with
reportUndocumented
.Default:
false
- suppressObviousFunctions
Whether to suppress obvious functions.
A function is considered to be obvious if it is:
Inherited from
kotlin.Any
,Kotlin.Enum
,java.lang.Object
orjava.lang.Enum
, such asequals
,hashCode
,toString
.Synthetic (generated by the compiler) and does not have any documentation, such as
dataClass.componentN
ordataClass.copy
.
Default:
true
- suppressInheritedMembers
Whether to suppress inherited members that aren't explicitly overridden in a given class.
Note: This can suppress functions such as
equals
/hashCode
/toString
, but cannot suppress synthetic functions such asdataClass.componentN
anddataClass.copy
. UsesuppressObviousFunctions
for that.Default:
false
- offlineMode
Whether to resolve remote files/links over your network.
This includes package-lists used for generating external documentation links. For example, to make classes from the standard library clickable.
Setting this to
true
can significantly speed up build times in certain cases, but can also worsen documentation quality and user experience. For example, by not resolving class/member links from your dependencies, including the standard library.Note: You can cache fetched files locally and provide them to Dokka as local paths. See
externalDocumentationLinks
section.Default:
false
Source set configuration
Dokka allows configuring some options for Kotlin source sets:
- suppress
Whether this source set should be skipped when generating documentation.
Default:
false
- displayName
The display name used to refer to this source set.
The name is used both externally (for example, as source set name visible to documentation readers) and internally (for example, for logging messages of
reportUndocumented
).By default, the value is deduced from information provided by the Kotlin Gradle plugin.
- documentedVisibilities
The set of visibility modifiers that should be documented.
This can be used if you want to document
protected
/internal
/private
declarations, as well as if you want to excludepublic
declarations and only document internal API.This can be configured on per-package basis.
Default:
DokkaConfiguration.Visibility.PUBLIC
- reportUndocumented
Whether to emit warnings about visible undocumented declarations, that is declarations without KDocs after they have been filtered by
documentedVisibilities
and other filters.This setting works well with
failOnWarning
.This can be configured on per-package basis.
Default:
false
- skipEmptyPackages
Whether to skip packages that contain no visible declarations after various filters have been applied.
For example, if
skipDeprecated
is set totrue
and your package contains only deprecated declarations, it is considered to be empty.Default:
true
- skipDeprecated
Whether to document declarations annotated with
@Deprecated
.This can be configured on per-package basis.
Default:
false
- suppressGeneratedFiles
Whether to document/analyze generated files.
Generated files are expected to be present under the
{project}/{buildDir}/generated
directory.If set to
true
, it effectively adds all files from that directory to thesuppressedFiles
option, so you can configure it manually.Default:
true
- jdkVersion
The JDK version to use when generating external documentation links for Java types.
For example, if you use
java.util.UUID
in some public declaration signature, and this option is set to8
, Dokka generates an external documentation link to JDK 8 Javadocs for it.Default: JDK 8
- languageVersion
The Kotlin language version used for setting up analysis and @sample environment.
By default, the latest language version available to Dokka's embedded compiler is used.
- apiVersion
The Kotlin API version used for setting up analysis and @sample environment.
By default, it is deduced from
languageVersion
.- noStdlibLink
Whether to generate external documentation links that lead to the API reference documentation of Kotlin's standard library.
Note: Links are generated when
noStdLibLink
is set tofalse
.Default:
false
- noJdkLink
Whether to generate external documentation links to JDK's Javadocs.
The version of JDK Javadocs is determined by the
jdkVersion
option.Note: Links are generated when
noJdkLink
is set tofalse
.Default:
false
- noAndroidSdkLink
Whether to generate external documentation links to the Android SDK API reference.
This is only relevant in Android projects, ignored otherwise.
Note: Links are generated when
noAndroidSdkLink
is set tofalse
.Default:
false
- includes
A list of Markdown files that contain module and package documentation.
The contents of the specified files are parsed and embedded into documentation as module and package descriptions.
See Dokka gradle example for an example of what it looks like and how to use it.
- platform
The platform to be used for setting up code analysis and @sample environment.
The default value is deduced from information provided by the Kotlin Gradle plugin.
- sourceRoots
The source code roots to be analyzed and documented. Acceptable inputs are directories and individual
.kt
/.java
files.By default, source roots are deduced from information provided by the Kotlin Gradle plugin.
- classpath
The classpath for analysis and interactive samples.
This is useful if some types that come from dependencies are not resolved/picked up automatically.
This option accepts both
.jar
and.klib
files.By default, classpath is deduced from information provided by the Kotlin Gradle plugin.
- samples
A list of directories or files that contain sample functions which are referenced via the @sample KDoc tag.
Source link configuration
The sourceLinks
configuration block allows you to add a source
link to each signature that leads to the remoteUrl
with a specific line number. (The line number is configurable by setting remoteLineSuffix
).
This helps readers to find the source code for each declaration.
For an example, see the documentation for the count()
function in kotlinx.coroutines
.
- localDirectory
The path to the local source directory. The path must be relative to the root of the current project.
- remoteUrl
The URL of the source code hosting service that can be accessed by documentation readers, like GitHub, GitLab, Bitbucket, etc. This URL is used to generate source code links of declarations.
- remoteLineSuffix
The suffix used to append the source code line number to the URL. This helps readers navigate not only to the file, but to the specific line number of the declaration.
The number itself is appended to the specified suffix. For example, if this option is set to
#L
and the line number is 10, the resulting URL suffix is#L10
.Suffixes used by popular services:
GitHub:
#L
GitLab:
#L
Bitbucket:
#lines-
Default:
#L
Package options
The perPackageOption
configuration block allows setting some options for specific packages matched by matchingRegex
.
- matchingRegex
The regular expression that is used to match the package.
Default:
.*
- suppress
Whether this package should be skipped when generating documentation.
Default:
false
- skipDeprecated
Whether to document declarations annotated with
@Deprecated
.This can be configured on source set level.
Default:
false
- reportUndocumented
Whether to emit warnings about visible undocumented declarations, that is declarations without KDocs after they have been filtered by
documentedVisibilities
and other filters.This setting works well with
failOnWarning
.This can be configured on source set level.
Default:
false
- documentedVisibilities
The set of visibility modifiers that should be documented.
This can be used if you want to document
protected
/internal
/private
declarations within this package, as well as if you want to excludepublic
declarations and only document internal API.This can be configured on source set level.
Default:
DokkaConfiguration.Visibility.PUBLIC
External documentation links configuration
The externalDocumentationLink
block allows the creation of links that lead to the externally hosted documentation of your dependencies.
For example, if you are using types from kotlinx.serialization
, by default they are unclickable in your documentation, as if they are unresolved. However, since the API reference documentation for kotlinx.serialization
is built by Dokka and is published on kotlinlang.org, you can configure external documentation links for it. Thus allowing Dokka to generate links for types from the library, making them resolve successfully and clickable.
By default, external documentation links for Kotlin standard library, JDK, Android SDK and AndroidX are configured.
- url
The root URL of documentation to link to. It must contain a trailing slash.
Dokka does its best to automatically find
package-list
for the given URL, and link declarations together.If automatic resolution fails or if you want to use locally cached files instead, consider setting the
packageListUrl
option.- packageListUrl
The exact location of a
package-list
. This is an alternative to relying on Dokka automatically resolving it.Package lists contain information about the documentation and the project itself, such as module and package names.
This can also be a locally cached file to avoid network calls.
Complete configuration
Below you can see all possible configuration options applied at the same time.