Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/squareup/leakcanary/watcher/R

Question

After adding LeakCanary as a dependency to my android gradle:

compile 'com.squareup.leakcanary:leakcanary-android:1.5.2'

I've got this error when building application:

:app:transformClassesWithDexForDebug
AGPBI: {"kind":"error","text":"Uncaught translation error: java.lang.IllegalArgumentException: already added: Lcom/squareup/leakcanary/watcher/R;","sources":[{}]}
AGPBI: {"kind":"error","text":"1 error; aborting","sources":[{}]}

FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:transformClassesWithDexForDebug'.
> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: 
com.android.ide.common.process.ProcessException: Return code 1 for dex process

I'm not including this library anywhere else, and without this compile dependency of leakcanary, my application is building fine.

I tried to look if I have some hidden canary dependency

./gradlew -q dependencies app:dependencies --configuration compile | grep com.squareup
 \--- com.squareup.leakcanary:leakcanary-android:1.5.2
      \--- com.squareup.leakcanary:leakcanary-analyzer:1.5.2
           +--- com.squareup.leakcanary:leakcanary-watcher:1.5.2
           \--- com.squareup.haha:haha:2.0.3

but there is only this expected one (I assume).

Exactly the same output is when I'm including this library using code from their FAQ

debugCompile 'com.squareup.leakcanary:leakcanary-android:1.5.2'
releaseCompile 'com.squareup.leakcanary:leakcanary-android-no-op:1.5.2'

Answer 1

This error is related to dex file (Android bytecode for your .class files)

multidex is needed when your code methods exceed the max limit on a single dex file which is 64k methods calls.

preDexLibraries is used when you want to build dex file out of libraries so that you don't build dex files of the library in further builds. In your case, because of this, it was creating 2 instances of the library dex files and causing error -

already added: Lcom/squareup/leakcanary/watcher/R;","sources"