How to manage the support libraries in a multi-module projects. Thanks to Fernando Cejas (http://fernandocejas.com/)

README.md

Centralize the support libraries dependencies in gradle

Working with multi-modules project, it is very useful to centralize the dependencies, especially the support libraries.

A very good way is to separate gradle build files, defining something like:

root
  --gradleScript
  ----dependencies.gradle
  --module1
  ----build.gradle
  --build.gradle

In gradleScript/dependecies.gradle:

ext {
    //Version
    supportLibrary = '22.2.1'

    //Support Libraries dependencies
    supportDependencies = [
            design           :         "com.android.support:design:${supportLibrary}",
            recyclerView     :         "com.android.support:recyclerview-v7:${supportLibrary}",
            cardView         :         "com.android.support:cardview-v7:${supportLibrary}",
            appCompat        :         "com.android.support:appcompat-v7:${supportLibrary}",
            supportAnnotation:         "com.android.support:support-annotations:${supportLibrary}",
    ]
}

In the top level file build.gradle:

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'
    }
}

// Load dependencies
apply from: 'gradleScript/dependencies.gradle'

In the module1/build.gradle:

// Module build file

dependencies {
    //......
    compile supportDependencies.appCompat
    compile supportDependencies.design
}

app_build.gradle

// Module build file

dependencies {
    //......
    compile supportDependencies.appCompat
    compile supportDependencies.design
}

build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'
    }
}

// Load dependencies
apply from: 'dependencies.gradle'

dependencies.gradle

ext {
    //Version
    supportLibrary = '22.2.1'

    //Support Libraries dependencies
    supportDependencies = [
            design           :         "com.android.support:design:${supportLibrary}",
            recyclerView     :         "com.android.support:recyclerview-v7:${supportLibrary}",
            cardView         :         "com.android.support:cardview-v7:${supportLibrary}",
            appCompat        :         "com.android.support:appcompat-v7:${supportLibrary}",
            supportAnnotation:         "com.android.support:support-annotations:${supportLibrary}",
    ]
}

Thank you so much

Very useful tip

Also, you can union all supportDependencies in following way:
compile supportDependencies.values()
instead of writing them one by one

Doesn't work for me.

I have:

Error:(48, 0) Cannot convert a null value to an object of type Dependency.
The following types/formats are supported:
  - Instances of Dependency.
  - String or CharSequence values, for example 'org.gradle:gradle-core:1.0'.
  - Maps, for example [group: 'org.gradle', name: 'gradle-core', version: '1.0'].
  - FileCollections, for example files('some.jar', 'someOther.jar').
  - Projects, for example project(':some:project:path').
  - ClassPathNotation, for example gradleApi().

Because of:

dependencies {
    // SUPPORT
    compile supportDependencies.appcompat
    compile supportDependencies.design
    compile supportDependencies.recyclerview
    ...
}

HELP :(

@lopspower you're not accessing the properties correctly. If you notice in the dependencies.gradle, the dependencies are declared as part of the ext closure. Also, if you notice in the root build.gradle, the dependencies.gradle is applied. Therefore, the dependency values are located on the root project's ext closure. Therefore, you would access them:
compile rootProject.ext.supportDependencies.appcompat

There is a good sample from artem-zinnatullin

@lopspower you wrote supportDependencies.appcompat and it should be supportDependencies.appCompat. It is case sensitive :)

You may also build your grade:app in following manner:

android{
[...]
ext{
    supportLibrary = '25.1.0'
    playServices = '9.8.0'
    firebase = playServices
}
dependencies {
   [...]
    compile "com.google.android.gms:play-services-location:${playServices}"
    compile "com.google.android.gms:play-services-maps:${playServices}"
    compile "com.google.firebase:firebase-core:${firebase}"
    compile "com.google.firebase:firebase-messaging:${firebase}"

    compile "com.android.support:appcompat-v7:${supportLibrary}"
    compile "com.android.support:design:${supportLibrary}"
    compile "com.android.support:palette-v7:${supportLibrary}"
}

Just don't forget to wrap dependencies in " " instead of ' '

Worked like a charm!

awsome tip !!

By this way Android Studio doesn't notify for newer version of dependencies.

excellent

Very nice!
Is it possible to similarily extract "complex" dependencies to another file, in a way they can be included with one line or together with a whole list of deps? Two examples:

    compile('com.crashlytics.sdk.android:crashlytics:2.6.7@aar') {
        transitive = true;
    }
    
    compile('com.github.tony19:logback-android-classic:1.1.1-6') {
        exclude group: 'com.google.android', module: 'android'
    }

Best I can think of is just replacing the full package-and-version leaving the rest intact: compile(libs.someVar) { ... }, but then I can't use that dependency together with others in a list, like you did with compile supportDependencies.values().

Another question: is there a way for Android Studio to highlight dependencies with new versions using this method, same as they were highlighted in build.gradle originally? Same question for auto-detecting changes in the dependencies.gradle file (if I change it, there is no prompt to do a gradle sync, like when changing any build.gradle file).

That's a very useful gist! 😮 👍

Another question: is there a way for Android Studio to highlight dependencies with new versions using this method, same as they were highlighted in build.gradle originally? Same question for auto-detecting changes in the dependencies.gradle file (if I change it, there is no prompt to do a gradle sync, like when changing any build.gradle file).

+1 Also interested in this.

@quezak and @Belka1000867 compile (and implementation) is a function taking a string as an agrument. So in the same way as you can use the vars directly, i.e. implementation thirdParty.crashlytics you can also use them as such:

    implementation(thirdParty.crashlytics) {
        transitive = true
    }

Another question: is there a way for Android Studio to highlight dependencies with new versions using this method, same as they were highlighted in build.gradle originally? Same question for auto-detecting changes in the dependencies.gradle file (if I change it, there is no prompt to do a gradle sync, like when changing any build.gradle file).

Is there any way to highlight new versions by using this approach?

Thanks a lot. This was helpful

@abeemukthees, @Belka1000867 and @quezak, you can use the following library to check for updates: gradle-versions-plugin.

It does not make the dependency yellow, but it generates a report with all updates, like this:

 - com.android.tools.lint:lint-gradle [26.4.1 -> 26.6.0-alpha03]
     https://developer.android.com/studio
 - com.google.android.material:material [1.0.0 -> 1.1.0-alpha07]
     http://developer.android.com/tools/extras/support-library.html
 - com.pinterest:ktlint [0.32.0 -> 0.33.0]
     https://github.com/pinterest/ktlint
 - io.gitlab.arturbosch.detekt:detekt-cli [1.0.0-RC14 -> 1.0.0-RC15]
     https://arturbosch.github.io/detekt
 - io.reactivex.rxjava2:rxandroid [2.1.0 -> 2.1.1]
     https://github.com/ReactiveX/RxAndroid
 - io.reactivex.rxjava2:rxjava [2.2.0 -> 2.2.9]
     https://github.com/ReactiveX/RxJava
 - junit:junit [4.12 -> 4.13-beta-3]
     http://junit.org

It is better than check one by one manually. 😝