ZipException: ZIP file must have at least one entry in gradle build in android studio

Question

Importing an ancient eclipse android project of mine in android studio. Build fails with:

ImmutableJarInput{name=main, file=C:\Dropbox\eclipse_workspaces\_android_studio\monitoringModel\build\intermediates\transforms\mergeJavaRes\release\jars\2\3\main.jar, contentTypes=RESOURCES, scopes=PROJECT,PROJECT_LOCAL_DEPS, status=NOTCHANGED}
ImmutableDirectoryInput{name=release, file=C:\Dropbox\eclipse_workspaces\_android_studio\monitoringModel\build\intermediates\classes\release, contentTypes=CLASSES, scopes=PROJECT, changedFiles={}}
:monitoringModel:transformClassesAndResourcesWithSyncLibJarsForRelease FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':monitoringModel:transformClassesAndResourcesWithSyncLibJarsForRelease'.
> java.util.zip.ZipException: ZIP file must have at least one entry

* Try:
Run with --info or --debug option to get more log output.

* Exception is:
org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':monitoringModel:transformClassesAndResourcesWithSyncLibJarsForRelease'.
...
Caused by: java.lang.RuntimeException: java.util.zip.ZipException: ZIP file must have at least one entry
...
Caused by: java.util.zip.ZipException: ZIP file must have at least one entry

New to gradle - how should I debug this ?

Answer 1

Well there is a file build.gradle where I read:

dependencies {
    compile project(':androidHelpers')
    compile files('libs/zip4j-1.3.1-javadoc.jar')
    compile files('libs/zip4j_1.3.1.jar')
}

Now libs/zip4j-1.3.1-javadoc.jar was not meant to be compiled (obviously) - was excluded in eclipse project files, bug number one.

So I went ahead and commented it out:

dependencies {
    compile project(':androidHelpers')
//    compile files('libs/zip4j-1.3.1-javadoc.jar')
    compile files('libs/zip4j_1.3.1.jar')
}

The IDE helpfully informed me that build files changed and I should "sync" - which I did and kept getting the same exception ! So I thought it was the other file and that led me to a goose chase - I unpacked it and repacked it etc following random google advice. Neither the exception or (of course) the debug output referred to the problematic file. The console was displaying:

Error:java.util.zip.ZipException: error in opening zip file
y be corrupt (this sometimes occurs after a network connection timeout.)
<a href="syncProject">Re-download dependencies and sync project (requires network)</a>
<a href="syncProject">Re-download dependencies and sync project (requires network)</a>

(sic - second bug) which made me think it was the libs/zip4j_1.3.1.jar that was problematic. Well turns out to be that sync was not enough - I had to Build > Clean Project cause gradle (despite sync) was trying to compile the javadoc zip that had cached somewhere (third bug):

Input file C:\\Dropbox\\eclipse_workspaces_android_studio\\monitoringModel\\build\\intermediates\\bundles\\release\\libs\\zip4j-1.3.1-javadoc.jar has been added.

Three bugs and counting - if anyone knows how to avoid these pitfalls - or actually why on earth gradle keeps its cache when syncing please comment.

Answer 2

I change

dependencies {
    compile project(':androidHelpers')
    compile files('libs/zip4j-1.3.1-javadoc.jar')
    compile files('libs/zip4j_1.3.1.jar')
}

to

  dependencies {
        compile project(':androidHelpers')
        provide files('libs/zip4j-1.3.1-javadoc.jar')
        provide files('libs/zip4j_1.3.1.jar')
    }