what's the meaning of @aar with transitive = true

Question

i use crashlytics only as an example.

what's is the difference from

    compile('com.crashlytics.sdk.android:crashlytics:2.6.8@aar') { transitive = true; }

and

    compile 'com.crashlytics.sdk.android:crashlytics:2.6.8'

Answer 1

If you use the ...@artifacttype notation in a Gradle dependency it means "only get me this artifact and no transitive dependencies". By additionally setting transitive = true, you are fetching the transitive dependencies despite that fact.

The first version gets the aar with dependencies and as far as I remember the second always gets the jar if one is present and else nothing but the dependencies. Add configurations.compile.each { println it } to output the actual files in the configuration and you should see the difference.

In the case of crashlytics there is no difference:

compile 'com.crashlytics.sdk.android:crashlytics:2.6.8'
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/crashlytics/2.6.8/2f667ae0609d82045cbe602d38df3fbf2c9528dd/crashlytics-2.6.8.aar
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/beta/1.2.5/f73d30657bb44ecb79d434a4ae3fb7d887371d84/beta-1.2.5.aar
/home/xan/.gradle/caches/modules-2/files-2.1/io.fabric.sdk.android/fabric/1.3.17/85fc9aae9009f6fb2beaf23fa0ce1ae13f124413/fabric-1.3.17.aar
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/crashlytics-core/2.3.17/f3bed4c297be8d30dc5aa7f18b06dff75435bde4/crashlytics-core-2.3.17.aar
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/answers/1.3.13/83dc1dd439c7da04ce9705f18037fe7551ae06bc/answers-1.3.13.aar

compile('com.crashlytics.sdk.android:crashlytics:2.6.8@aar') { transitive = true; }
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/crashlytics/2.6.8/2f667ae0609d82045cbe602d38df3fbf2c9528dd/crashlytics-2.6.8.aar
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/beta/1.2.5/f73d30657bb44ecb79d434a4ae3fb7d887371d84/beta-1.2.5.aar
/home/xan/.gradle/caches/modules-2/files-2.1/io.fabric.sdk.android/fabric/1.3.17/85fc9aae9009f6fb2beaf23fa0ce1ae13f124413/fabric-1.3.17.aar
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/crashlytics-core/2.3.17/f3bed4c297be8d30dc5aa7f18b06dff75435bde4/crashlytics-core-2.3.17.aar
/home/xan/.gradle/caches/modules-2/files-2.1/com.crashlytics.sdk.android/answers/1.3.13/83dc1dd439c7da04ce9705f18037fe7551ae06bc/answers-1.3.13.aar