41

I am going to convert my Android projects from Ant to Gradle.

My Eclipse workspace is very simple:

Workspace
     MyApp
     MyApp-AndroidLibrary

When I add a build.gradle file in MyApp, I want to reference my Android library project:

apply plugin: 'android'

dependencies {
     compile fileTree(dir: 'libs', include: '*.jar')
     compile project(':MyApp-AndroidLibrary')
}

When I run gradle build, there is an error "Project with path ':MyApp-AndroidLibrary' could not be found in root project", I googled for this, and found I need to setup a "settings.gradle" file in my workspace directory, to add 

include ":MyApp"
include ":MyApp-AndroidLibrary"

This looks too bad for me, why Gradle need a settings.gradle file, why not just extract the projects I defined in the dependencies?

And what include really means? What if I have anotoher app and some other shared libraries in workspace, the structure may look like this:

Workspace
     App1
     App2
     Library1(Used by App1 & App2)
     Library2(Used only by App1)
     Library3(Used only by App2)

Because there is only ONE settings.gradle file, I had to add them all into settings.gradle. That does not smell good.

And yes, I can re-organize the strucuture to make Library2 into a child directory of App1, and Library3 to be a child directory of App2, but what about Library1?

Any comment on this?

Jose_GD
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virsir
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2 Answers2

13

You are asking several different questions. Here are some hints:

  • ':MyApp-AndroidLibrary' is a logical project path, which gets mapped to a physical path based on information provided in settings.gradle.
  • A multi-project build can have an arbitrary directory structure, which is configured in settings.gradle. No need to move directories around, unless you want to.
  • Eclipse workspace and Gradle build are separate boundaries. You can have multiple builds in the same workspace.
  • When working with libraries built from source, you can either make them part of the same build, or have a separate build for them. In the latter case, you need to make sure to build the library before the app, and exchange artifacts via a Maven or Ivy repository. This could be automated using a CI server and a corporate Maven/Ivy repository. Alternatively, you could trigger the library's build manually on your machine and use a local Maven/Ivy repository.

For more information, check out the Gradle User Guide, especially the chapter on multi-project builds.

Peter Niederwieser
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    I'm still not sure why there is no default behavior(which matches with directory structure as it would in most cases) for that which would make a lot of use cases simpler. – yhpark Mar 21 '14 at 20:21
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    So are you saying that Gradle indeed does not use the information in `settings.gradle` to determine project dependencies, but only to map the project dependencies as defined in the various `build.gradle` files from logical paths to physical paths? – sschuberth Aug 18 '14 at 07:55
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    The information in `settings.gradle` tells Gradle which subprojects are part of this build, what their logical and physical paths are, how their build scripts are named, etc. It does not, and cannot, tell Gradle what the dependencies between the subprojects are. – Peter Niederwieser Aug 18 '14 at 22:48
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    Just wonder why they decided on a *separate* file for settings.gradle? Why not put that info, too, in build.gradle? Perhaps in a settings{...} section or so... is there a technical reason for this? – Rop Jan 29 '16 at 23:27
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    I also think this is a pretty good question. Penetrating gradle's design seems pointlessly difficult. Is there actually a reason for this file's existence? This definitely doesn't answer the question at all. – Fulluphigh Jun 03 '16 at 16:26
0

Just in case people (like myself or gladman) still have this problem and couldn't find a solution. With the current version of Gradle you can do this:

Move the file settings.gradle to the directory My-App and replace the include by includeFlat 'MyApp-AndroidLibrary'. This should fix the problem.

Also compare this question and see this section in the Gradle User Guide for further details.

Community
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Joerg
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