2. Dependency Configurations (original) (raw)

Gradle represents the scope of a dependency with the help of a Configuration. Every configuration can be identified by a unique name.

Many Gradle plugins add pre-defined configurations to your project.

The Java Library plugin is used to define a project that produces a Java library. The plugin adds many dependency configurations. These configurations represent the various classpaths needed for source code compilation, executing tests, and more:

Configuration Name	Description	Used to:
api	Dependencies required for both compilation and runtime, and included in the published API.	Declare Dependencies
implementation	Dependencies required for both compilation and runtime.	Declare Dependencies
compileOnly	Dependencies needed only for compilation, not included in runtime or publication.	Declare Dependencies
compileOnlyApi	Dependencies needed only for compilation, but included in the published API.	Declare Dependencies
runtimeOnly	Dependencies needed only at runtime, not included in the compile classpath.	Declare Dependencies
testImplementation	Dependencies required for compiling and running tests.	Declare Dependencies
testCompileOnly	Dependencies needed only for test compilation.	Declare Dependencies
testRuntimeOnly	Dependencies needed only for running tests.	Declare Dependencies

Dependency declaration Configurations

The dependency declaration configurations (compileOnly, implementation, runtimeOnly) focus on declaring and managing dependencies based on their usage (compile time, runtime, API exposure):

dependencies {
    implementation("com.google.guava:guava:30.1.1-jre")     // Implementation dependency
    compileOnly("org.projectlombok:lombok:1.18.20")         // Compile-only dependency
    runtimeOnly("mysql:mysql-connector-java:8.0.23")        // Runtime-only dependency
}

dependencies {
    implementation("com.google.guava:guava:30.1.1-jre")     // Implementation dependency
    compileOnly("org.projectlombok:lombok:1.18.20")         // Compile-only dependency
    runtimeOnly("mysql:mysql-connector-java:8.0.23")        // Runtime-only dependency
}

Other Configurations

There are other types of configurations (such as runtimeClasspath, compileClasspath, apiElements, runtimeElements), but they are not used to declare dependencies.

It is also possible to create custom configurations. A custom configuration allows you to define a distinct group of dependencies that can be used for specific purposes, such as toolchains or code generation, separate from the standard configurations (e.g., implementation, testImplementation):

build.gradle.kts

val customConfig by configurations.creating

dependencies {
    customConfig("org.example:example-lib:1.0")
}

build.gradle

configurations {
    customConfig
}

dependencies {
    customConfig("org.example:example-lib:1.0")
}

Creating a custom configuration helps manage and isolate dependencies, ensuring they are only included in the relevant classpaths and build processes.