In Gradle, how do I declare common dependencies in a single place?

Question

In Maven there is a very useful feature when you can define a dependency in the <dependencyManagement> section of the parent POM, and reference that dependency from child modules without specifying the version or scope or whatever.

What are the alternatives in Gradle?

Answer 1

You can declare common dependencies in a parent script:

ext.libraries = [ // Groovy map literal
    spring_core: "org.springframework:spring-core:3.1",
    junit: "junit:junit:4.10"
]

From a child script, you can then use the dependency declarations like so:

dependencies {
    compile libraries.spring_core
    testCompile libraries.junit
}

To share dependency declarations with advanced configuration options, you can use DependencyHandler.create:

libraries = [
    spring_core: dependencies.create("org.springframework:spring-core:3.1") {
        exclude module: "commons-logging"
        force = true
    }
]

Multiple dependencies can be shared under the same name:

libraries = [
    spring: [ // Groovy list literal
        "org.springframework:spring-core:3.1", 
        "org.springframework:spring-jdbc:3.1"
    ]
]

dependencies { compile libraries.spring } will then add both dependencies at once.

The one piece of information that you cannot share in this fashion is what configuration (scope in Maven terms) a dependency should be assigned to. However, from my experience it is better to be explicit about this anyway.