Getting pure-java modules with ThreeTenBP to play nice with ThreeTenABP?

Disclaimer: this is probably a gradle config issue rather than an issue with this library per-se. But hopefully this issue is relevant to android developers wanting to use JSR 310 in multi-module projects.

I have a pure java (non-android) gradle module called common with some utility functions for building ZonedDateTime objects. It depends on the standard jvm backport library (org.threeten:threetenbp).

What I’d like is to have the android app module depend on the common module to make use of these platform-independent utility functions, but depend on threetenABP instead for performance. Should this be possible? Attempting to do it naiively gives this build error:

Error:Execution failed for task ':app:transformResourcesWithMergeJavaResForDevelopDebug'.
> com.android.build.api.transform.TransformException: com.android.builder.packaging.DuplicateFileException: Duplicate files copied in APK org/threeten/bp/format/ChronologyText.properties
  	File1: /Users/matthewcl/.gradle/caches/modules-2/files-2.1/org.threeten/threetenbp/1.3.1/5769e9c27cd5ba74cd3a73785dde0bbb5a2d3c0d/threetenbp-1.3.1.jar
  	File2: /Users/matthewcl/.gradle/caches/modules-2/files-2.1/org.threeten/threetenbp/1.3.1/fecd59cfa6acebf3d0f2f41f55a1cc3e24e59726/threetenbp-1.3.1-no-tzdb.jar

From what I understand, the same public classes and interfaces are in use in both modules (e.g. ZonedDateTime). It seems like something like gradle’s provided keyword to have compilation succeed and yet use ABP at runtime would work, but I haven’t had much success with it.

Any thoughts?

[tmtron]

I got it working like this:

• In the Android application module “app” (which builds the apk): use ThreeTen Backport for Android (including timezone-info): implementation 'com.jakewharton.threetenabp:threetenabp:1.0.5'
• In Android library modules and plain Java modules (e.g. “common”):
  • use ThreeTen Backport without time-zone info for compilation only: compileOnly 'org.threeten:threetenbp:1.3.6:no-tzdb'
  • and use the java ThreeTen Backport with time-zone info for testing: testImplementation 'org.threeten:threetenbp:1.3.6'

I think, the substitution that @JakeWharton mentions in this comment should only be required when you use an external library which uses 'org.threeten:threetenbp' to avoid the slow loading of the time-zone info.

[Byronium]

@tmtron Correct me if I’m wrong, but the reason your solution works is the compileOnly declaration. compileOnly dependencies are not included on the runtime class-path and are non-transitive (meaning they will not be included in dependent projects). However, in most cases, wouldn’t you need the ThreeTen library to be accessible at runtime by the Java-only module common? Also, is there any particular reason you’re using the no-tzdb version of ThreeTen Backport?

Anyways, in my case, I needed the time-zone version of ThreeTenBackport in my Java-only module and I also couldn’t make it a compileOnly dependency, so I just excluded it in my Android module app where I define the common module as a dependency.

In my Java-only common module build.gradle:

implementation 'org.threeten:threetenbp:1.3.3'

In my Android app module build.gradle:

implementation (project(":common")) {
    // exclude the threetenbp dependency from the `common` module
    exclude group: 'org.threeten', module: 'threetenbp' 
}

implementation 'com.jakewharton.threetenabp:threetenabp:1.0.5'

(sidenote: I’m using the new implementation syntax instead of compile)

Just another solution in case it helps anyone!