Ozzie Ozzie - 4 months ago 21
Android Question

Android Studio: Add jar as library?

I'm trying to use the new Android Studio but i can't seem to get it working correctly.

I'm using the Gson-library to serialize/deserialize JSON-objects. But the library somehow isn't included in the build.

I created a new project with just a MainActivity. Copied gson-2.2.3.jar in the /libs folder and added it as a library (right click->Add as library). This includes the jar in android studio so it can be referenced from the source files.

When I try to run the project it cannot compile so i added

compile files('libs/gson-2.2.3.jar')

to the dependencies in de .gradle file. After that it compiles correctly but when running the application i get a ClassDefNotFoundException.
Does anyone know what i'm doing wrong?


I've been struggling with the same thing for many hours, trying to get the Gson jar to work no less. I finally cracked it – here are the steps I took:

  1. Put the Gson jar (in my case, gson-2.2.4.jar) into the libs folder
  2. Right click it and hit 'Add as library'
  3. Ensure that compile files('libs/gson-2.2.4.jar') is in your build.gradle file
  4. Do a clean build (you can probably do this fine in Android Studio, but to make sure I navigated in a terminal to the root folder of my app and typed gradlew clean. I'm on Mac OS X, the command might be different on your system

After I did the above four, it started working fine. I think the 'Add as library' step was the one I'd previously missed, and it didn't work until I cleaned it either.

[Edit - added the build.gradle step which is also necessary as others have pointed out]