The output jar is empty. Did you specify the proper '-keep' options?

问题

I am trying to build a release APK file from ant and this is what i m getting in my console

D:\AndroidSDK\android-sdk_r18-windows\android-sdk-windows\tools\ant\build.xml:595: The following error occurred while executing this line:D:\AndroidSDK\android-sdk_r18windows\android-sdk-windows\tools\ant\build.xml:864: The output jar is empty. Did you specify the proper '-keep' options?

What is this error and how can i resolve it..M using the latest SDK(API-17) with Revision 21.1 All java_home,Ant_home are set

回答1:

For library projects, I needed to add -dontshrink option to proguard config file - proguard was shrinking ALL my classes.

回答2:

When using gradle build system, there is no need to modify proguard-rules.pro.

Just inside specified buildType define minifyEnabled false. Example:

buildTypes {
    release {
        minifyEnabled false
    }
}

回答3:

Ohkk I got the answer myself..There was a problem in the Manifest file on the jar project which i was using as a library..The created the lib project,Updated it and referenced it to my main code .As in this LInk..and it worked:-) here

来源：https://stackoverflow.com/questions/14869315/the-output-jar-is-empty-did-you-specify-the-proper-keep-options