CODEWITHSUNDEEP
javaandroidgradlejarandroid-gradle-plugin
Denys Kniazhev-Support Ukraine
Denys Kniazhev-Support Ukraine

Reputation: 9102

Android java module "jar" file dependency issue

I have Android gradle project which consists of main module and a pure java library. The java library has a dependency on a jar file (Gson is shown here for demo purposes only):

tree structure

The project compiles fine but when I try to run it it fails with NoClassDefFoundError:

java.lang.NoClassDefFoundError: com.google.gson.Gson
    at com.example.JavaLibClass.javaMethod(JavaLibClass.java:7)
    at com.denisk.deptest.MainActivity.onCreate(MainActivity.java:15)
    at android.app.Activity.performCreate(Activity.java:5135)

If I replace jar dependency with regular Maven dependency, it works.

If I move jar dependency from javalib to app and introduce dependency Gson dependency in the activity, it works.

app/build.gradle dependencies:

dependencies {
    compile project(':javalib')
}

javalib/build.gradle:

apply plugin: 'java'

dependencies {
    compile files('libs/gson-2.2.4.jar')
}

MainActivity's onCreate (inside app):

@Override
protected void onCreate(Bundle savedInstanceState) {

    JavaLibClass javaLibClass = new JavaLibClass();
    javaLibClass.javaMethod();

}

JavaLibClass (inside javalib):

public class JavaLibClass {
    public void javaMethod() {
        Gson gson = new Gson();
    }
}

Github repository with the demo project:

https://github.com/denisk20/android-gradle-dependency-test

Am I doing something wrong or is it a bug?

Edit 1: It doesn't matter whether I build with Android Studio or with pure Gradle.

Edit 2: I have have tried it with android gradle plugin 1.4.0-beta4 from AOSP - same error.

Upvotes: 4

Views: 1511

Answers (2)

mhsmith
mhsmith

Reputation: 8111

The class which is failing to load probably has a missing dependency of its own. Annoyingly, the VM in Android 5.1 does not tell you what that dependency is. I found that when I ran my app on an older Android 2.3 device with the Dalvik VM, the missing dependency was identified in a log message.

Upvotes: 1

Ra Ka
Ra Ka

Reputation: 3055

Okay, Its not a bug actually, instead you need to import the jar file as a dependency in your project. I believe that you just put that Jar file in the lib folder of your project but did not import as dependency in your project. That is why the maven dependency is working fine since it automatically import it. So, go to File>Project Structure, Select your project under module section and on Dependency tab, add your jar file as File dependency by browsing to your lib folder. Now, rebuild your project, It should work fine.

Upvotes: 0

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