Gradle包含依赖项的依赖项

Question

Scenario

I have two Android libraries:

• Library A
• Library B

Library B depends on Library A and includes it from its build.gradle.

My Android app needs to use Library B and some base classes from Library A. The only success I've had in doing this is including both libraries in my Android app's build.gradle and setting transitive to false.

Question :

Is there a way for me to only add Library B and have access to its dependency from my Android app?

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Android Studio

Android Studio 3.1 Canary
Build #AI-171.4415322, built on October 24, 2017
JRE: 1.8.0_152-release-1012-b01 x86_64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Mac OS X 10.12.6

Gradle

3.1.0-alpha01

Answer 1

That's called a transitive dependency.

Gradle, and all other dependency systems handle this automatically. If B needs A, you get A. If you are not getting A, that means B's dependencies are not correct.

Whether you should explicitly call out A in your dependencies is a debated topic. I'm of the camp that you should not. My reasoning is that you can end up with something like this,

include B(v1.0) -depends on-> A(1.0)
include A(1.1)

Now, which version of A gets compiled into your app and used at runtime? A 1.0 or A 1.1? The answer depends on the implementation of the build system.

• If it's A 1.0, then YOU are compiling against 1.1 but running against 1.0.
• If it's 1.1, then B is compiled against 1.0 but is using 1.1 at runtime.

Answer 2

From comments if you need to use library A inside your app and your library A included into B using implementation project(':LibA') , then it won't be a transitive to your main app .

You have to include it into B using api , api project(':LibA') .

The api configuration should be used for dependencies that are exported to external modules (transitive dependency). Vice-Versa implementation configuration should be used for dependencies that are internal to the component (not transitive dependency) .