Dependency management with Gradle

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Dependency management with Gradle is easy to understand, and has many different approaches. If you are familiar with Maven or Ivy, Gradle is fully compatible with both approaches, as well as being able to support custom approaches. If you aren’t familiar with Gradle, there are great resources on their site to learn, it is recommended you give them a read to get comfortable with Gradle.

Guide to build.gradle

Gradle projects are managed by build.gradle files in their root directory. If you have used the gdx-setup.jar to build your libGDX project you will notice the structure: Structure Example

The root directory, and each sub directory contains a build.gradle file, for clarity we will define the dependencies in the root directory’s build.gradle file. (Note it can be done in each of the build.gradle scripts in the sub directories, it is just cleaner and easier to follow when it is handled all in one place)

Here is a small section of the default buildscript that is generated from the setup:

Full script you will see will differ slightly depending on what other modules you have

//Configuration for the script itself (aka, listing the dependencies of the script that lists dependencies - InSCRIPTion!)
buildscript {
    //Defines the repositories required by this script, e.g. hosting the android plugin
    repositories {
        //maven central repository, needed for the android plugin
        mavenCentral()
        //snapshot repository (in case this script depends on snapshot/prerelease artifacts)
        maven { url "https://oss.sonatype.org/content/repositories/snapshots/" }
        gradlePluginPortal()
        //local maven repository (advanced use)
        mavenLocal()
        google()
        maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
        maven { url 'https://s01.oss.sonatype.org/content/repositories/snapshots/' }
    }
    //Defines the artifacts this script depends on, e.g. the android plugin
    dependencies {
        //Adds the android gradle plugin as a dependency of this buildscript
        classpath "com.android.tools.build:gradle:8.1.4"
        classpath "org.docstr:gwt-gradle-plugin:$gwtPluginVersion"
    }
}

//Configuration common to all projects (:core, :desktop and :android in this example)
allprojects {
    //Defines gradle plugins used by all projects.
    //A plugin extends gradle with additional tasks, configurations, etc., with defaults set according to conventions.
    apply plugin: "eclipse"
    apply plugin: "idea"

    // This allows you to "Build and run using IntelliJ IDEA", an option in IDEA's Settings.
    idea {
        module {
        outputDir file('build/classes/java/main')
        testOutputDir file('build/classes/java/test')
        }
    }
}

configure(subprojects - project(':android')) {
  apply plugin: 'java-library'
  sourceCompatibility = 8
  compileJava {
    options.incremental = true
  }
  // From https://lyze.dev/2021/04/29/libGDX-Internal-Assets-List/
  // The article can be helpful when using assets.txt in your project.
  compileJava.doLast {
    // projectFolder/assets
    def assetsFolder = new File("${project.rootDir}/assets/")
    // projectFolder/assets/assets.txt
    def assetsFile = new File(assetsFolder, "assets.txt")
    // delete that file in case we've already created it
    assetsFile.delete()

    // iterate through all files inside that folder
    // convert it to a relative path
    // and append it to the file assets.txt
    fileTree(assetsFolder).collect { assetsFolder.relativePath(it) }.each {
      assetsFile.append(it + "\n")
    }
  }
}

subprojects {
    //Version of your game
    version = '1.0.0'
    ext.appName = 'MyOriginalGame'
    repositories {
        mavenCentral()
        maven { url 'https://s01.oss.sonatype.org' }
        // You may want to remove the following line if you have errors downloading dependencies.
        mavenLocal()
        maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
        maven { url 'https://s01.oss.sonatype.org/content/repositories/snapshots/' }
        maven { url 'https://jitpack.io' }
    }
}

eclipse.project.name = 'MyOriginalGame' + '-parent'

libGDX Dependencies

Dependencies are configured in the respective build.gradle file of each subproject. For example: core/build.gradle,android/build.gradle,html/build.gradle, etc. In order to add an external dependency to a project, you must declare the dependency correctly under the correct part of the buildscript.

(Some) libGDX extensions are mavenized and pushed to the maven repo, which means we can very easily pull them into our projects from the build.gradle file. You can see in the list below of the format that these dependencies take. If you are familiar with maven, notice the format:

implementation '<groupId>:<artifactId>:<version>:<classifier>'

Let’s take a quick example to see how this works with the android build.gradle file.

Here we see the dependencies for the FreeType Extension, say we want our Android project to have this dependency:

dependencies {
    coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:2.0.4'
    implementation "com.badlogicgames.gdx:gdx-backend-android:$gdxVersion"
    implementation project(':core')

    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-arm64-v8a"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-armeabi-v7a"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-x86"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-x86_64"
}

We know our FreeType extension has the following android declarations:

natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-arm64-v8a"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-armeabi-v7a"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86_64"

So all we need to do is whack it in the dependencies stub

dependencies {
    coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:2.0.4'
    implementation "com.badlogicgames.gdx:gdx-backend-android:$gdxVersion"
    implementation project(':core')

    natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-arm64-v8a"
    natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-armeabi-v7a"
    natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86"
    natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86_64"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-arm64-v8a"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-armeabi-v7a"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-x86"
    natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-x86_64"
}

Ensure that your Core project has the freetype extension in core/build.gradle

dependencies {
  api "com.badlogicgames.gdx:gdx-freetype:$gdxVersion"
  api "com.badlogicgames.gdx:gdx:$gdxVersion"
}

And we are done, our android project now has the freetype dependency. After this you will need to refresh your dependencies. Easy eh.

libGDX Extensions

Mavenized libGDX extensions ready to import from the build.gradle script include:

Box2D Gradle

Core Dependency:

api "com.badlogicgames.gdx:gdx-box2d:$gdxVersion"

Desktop Dependency:

implementation "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-desktop"

Android Dependency:

natives "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-arm64-v8a"
natives "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-armeabi-v7a"
natives "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-x86"
natives "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-x86_64"

iOS Dependency:

implementation "com.badlogicgames.gdx:gdx-box2d-platform:$gdxVersion:natives-ios"

HTML Dependency:

implementation "com.badlogicgames.gdx:gdx-box2d:$gdxVersion:sources"
implementation("com.badlogicgames.gdx:gdx-box2d-gwt:$gdxVersion:sources") {exclude group: "com.google.gwt", module: "gwt-user"}

and in ./html/src/yourgamedomain/GdxDefinition*.gwt.xml add <inherits name="com.badlogic.gdx.physics.box2d.box2d-gwt" />

Bullet Gradle

Core Dependency:

api "com.badlogicgames.gdx:gdx-bullet:$gdxVersion"

Desktop Dependency:

implementation "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-desktop"

Android Dependency:

natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-arm64-v8a"
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-armeabi-v7a"
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-x86"
natives "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-x86_64"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-arm64-v8a"

iOS Dependency:

implementation "com.badlogicgames.gdx:gdx-bullet-platform:$gdxVersion:natives-ios"

HTML Dependency: Not compatible!

FreeTypeFont Gradle

Core Dependency:

api "com.badlogicgames.gdx:gdx-freetype:$gdxVersion"

Desktop Dependency:

implementation "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-desktop"

Android Dependency:

natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-arm64-v8a"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-armeabi-v7a"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86"
natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86_64"

iOS Dependency:

implementation "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-ios"

iOS-MOE Dependency:

natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-ios"

HTML Dependency: Not compatible! See gdx-freetype-gwt for an alternative.

Controllers Gradle

Core Dependency:

api "com.badlogicgames.gdx-controllers:gdx-controllers-core:$gdxControllersVersion"

Desktop Dependency:

implementation "com.badlogicgames.gdx-controllers:gdx-controllers-desktop:$gdxControllersVersion"

Android Dependency:

implementation "com.badlogicgames.gdx-controllers:gdx-controllers-android:$gdxControllersVersion"

iOS Dependency:

implementation "com.badlogicgames.gdx-controllers:gdx-controllers-ios:$gdxControllersVersion"

HTML Dependency:

implementation "com.badlogicgames.gdx-controllers:gdx-controllers-core:$gdxControllersVersion:sources"
implementation("com.badlogicgames.gdx-controllers:gdx-controllers-gwt:$gdxControllersVersion:sources"){exclude group: "com.badlogicgames.gdx", module: "gdx-backend-gwt"}

and in ./html/src/yourgamedomain/GdxDefinition*.gwt.xml add <inherits name="com.badlogic.gdx.controllers" /> and <inherits name="com.badlogic.gdx.controllers.controllers-gwt" />

Tools Gradle

Core Dependency: Don’t put me in core!

Desktop Dependency (LWJGL2 Legacy Desktop only):

api "com.badlogicgames.gdx:gdx-tools:$gdxVersion"

Android Dependency: Not compatible!

iOS Dependency: Not compatible!

HTML Dependency: Not compatible!

Box2DLights Gradle

  • Note: this extension also requires the Box2D extension

Core Dependency:

api "com.badlogicgames.box2dlights:box2dlights:$box2dlightsVersion"

Desktop Dependency: No native dependency required.

Android Dependency: No native dependency required.

HTML Dependency:

implementation "com.badlogicgames.box2dlights:box2dlights:$box2dlightsVersion:sources"

and in ./html/src/yourgamedomain/GdxDefinition*.gwt.xml add <inherits name="Box2DLights" />

Ashley Gradle

  • Note: This extension release cycle is not dependent on the main libGDX library, and so it is not unusual to have a new version published between two libGDX releases. If you want to pull in a new (or different) version, check https://repo1.maven.org/maven2/com/badlogicgames/ashley/ashley/ and change the ashleyVersion value in the ext section.

Core Dependency:

api "com.badlogicgames.ashley:ashley:$ashleyVersion"

Desktop Dependency: No native dependency required.

Android Dependency: No native dependency required.

HTML Dependency:

implementation "com.badlogicgames.ashley:ashley:$ashleyVersion:sources"

and in ./html/src/yourgamedomain/GdxDefinition*.gwt.xml add <inherits name="com.badlogic.ashley_gwt" />

AI Gradle

  • Note: This extension release cycle is not dependent on the main libGDX library, and so it is not unusual to have a new version published between two libGDX releases. If you want to pull in a new (or different) version, check https://repo1.maven.org/maven2/com/badlogicgames/gdx/gdx-ai/ and change the aiVersion value in the ext section.

Core Dependency:

api "com.badlogicgames.gdx:gdx-ai:$aiVersion"

Desktop Dependency: No native dependency required.

Android Dependency: No native dependency required.

HTML Dependency:

implementation "com.badlogicgames.gdx:gdx-ai:$aiVersion:sources"

and in ./html/src/yourgamedomain/GdxDefinition*.gwt.xml add <inherits name="com.badlogic.gdx.ai" />

External Dependencies

Adding external repositories

Gradle finds files defined as dependencies by looking through all the repositories defined in the buildscript. Gradle understands several repository formats, which include Maven and Ivy.

Under the subprojects stub of the root build.gradle, you can see how repositories are defined. Here is an example:

subprojects {
    version = '1.0.0'
    ext.appName = 'MyOriginalGame'
    repositories {
        mavenCentral()
        maven { url 'https://s01.oss.sonatype.org' }
        // You may want to remove the following line if you have errors downloading dependencies.
        mavenLocal()
        maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
        maven { url 'https://s01.oss.sonatype.org/content/repositories/snapshots/' }
        maven { url 'https://jitpack.io' }f
    }
}

Adding Dependencies

External dependencies are identified by their group, name, version and sometimes classifier attributes.

dependencies {
    implementation group: 'com.badlogicgames.gdx', name: 'gdx', version: '1.0-SNAPSHOT', classifier: 'natives-desktop'
}

Gradle allows you to use shortcuts when defining external dependencies, the above configuration is the same as:

dependencies {
    implementation 'com.badlogicgames.gdx:gdx:1.0-SNAPSHOT:natives-desktop'
}

Mavenizing Local Dependencies

If you would prefer to use maven repositories to manage local .jar files, these two commands will take any local .jar file and install them (and their source) to your local maven repository.

mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>

mvn install:install-file -Dfile=<path-to-source-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging> -Dclassifier=sources

To then set up gradle to include your new dependency, edit your build.gradle file in the root project directory and edit the core project entry:

project(":core") {
   ...

    dependencies {
        ...
        implementation "<group-id>:<artifact-id>:<version>"
        implementation "<group-id>:<artifact-id>:<version>:sources"
    }
}

After this you will need to refresh your dependencies for your IDE to see, so run:
Command line - $ ./gradlew --refresh-dependencies
Eclipse - $ ./gradlew eclipse
IntelliJ - $ ./gradlew idea

Also, don’t forget that any dependencies added this way also need to be included in the GWT inheritance file.

File Dependencies

If you have a dependency that is not mavenized, you can still depend on them!

To do this, in your project stub in the subproject’s corresponding build.gradle file, locate the dependencies { } section and add the following:

dependencies {
    implementation fileTree(dir: 'libs', include: '*.jar')
}

This will include all the .jar files in the libs directory as dependencies.

NOTE: “dir” is relative to the project root, if you add the dependencies to your android project, ‘libs’ would need to be in the android/ directory. If you added the dependencies in the core project, ‘libs’ would need to be in the core/ directory.

An example with a more complete script:

project(":android") {
    apply plugin: "android"

    configurations { natives }

    dependencies {
        coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:2.0.4'
        implementation "com.badlogicgames.gdx:gdx-backend-android:$gdxVersion"
        implementation project(':core')

        natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-arm64-v8a"
        natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-armeabi-v7a"
        natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86"
        natives "com.badlogicgames.gdx:gdx-freetype-platform:$gdxVersion:natives-x86_64"
        natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-arm64-v8a"
        natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-armeabi-v7a"
        natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-x86"
        natives "com.badlogicgames.gdx:gdx-platform:$gdxVersion:natives-x86_64"
        implementation fileTree(dir: 'libs', include: '*.jar')
    }
}

It is worth nothing that these file dependencies are not included in the published dependency descriptor for your project, but they are included in transitive project dependencies within the same build.

Android Pitfall

When adding flat file dependencies to a project, for example the core project, you would need to duplicate the dependency declaration for the android project. This is because the Android Gradle plugin currently can’t handle transitive flat file dependencies.

For example, if you were to add the all the jars in your libs directory as dependencies for your project, you would need to do the following.

project(":core") {
   ...
   implementation fileTree(dir: '../libs', include: '*.jar')
   ...
}

// And also

project(":android") {
   ...
   implementation fileTree(dir: '../libs', include: '*.jar')
   ...
}

This is only required for the android project, all other projects inherit flat file dependencies OK.

Gwt Inheritance

Gwt is special, so in order to let the GWT compiler know what modules the project depends on, and inherits from, you need to let it know.

This is done in the gwt.xml files in the gwt sub directory. You will need to make the changes both to the GdxDefinition.gwt.xml and also the GdxDefinitionSuperdev.gwt.xml.

The default gwt.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit trunk//EN" "http://google-web-toolkit.googlecode.com/svn/trunk/distro-source/core/src/gwt-module.dtd">
<module rename-to="html">
	<inherits name='com.badlogic.gdx.backends.gdx_backends_gwt' />
	<inherits name='MyGameName' />
	<entry-point class='com.badlogic.mygame.client.HtmlLauncher' />

	<set-configuration-property name="gdx.assetpath" value="../android/assets" />
</module>

We depend on the libGDX gwt backend, as well as the core project, so we have them defined in a tag. So when you add your dependency via methods above, you need to add it here too!

libGDX Extension Inherits

These are the libGDX extensions that are supported in gwt

  • libGDX Core - <inherits name='com.badlogic.gdx.backends.gdx_backends_gwt' />
  • Box2d - <inherits name='com.badlogic.gdx.physics.box2d.box2d-gwt' />
  • Box2dLights - <inherits name='Box2DLights' />
  • Controllers - <inherits name='com.badlogic.gdx.controllers' /> and <inherits name='com.badlogic.gdx.controllers.controllers-gwt' />
  • Ashley - <inherits name='com.badlogic.ashley_gwt' />
  • AI - <inherits name='com.badlogic.gdx.ai' />

Dependency management for libraries

If you’re creating a library that people can include in their projects via gradle, you might need to replace the implementation keyword by api. Any dependency of your library that you declare with api will be visible and usable by others that depend on your library while implementation makes it only accessible for you.

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