Duplicated classes found in modules classes.jar

Question

Working with "Cxense SDK for Android", I'm getting the message of duplicated class:

Duplicate class android.support.v4.app.INotificationSideChannel found in modules classes.jar (**com.android.support:support-compat:27.1.1**) and classes.jar (**com.android.support:support-v4:22.2.0**)
Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules classes.jar (com.android.support:support-compat:27.1.1) and classes.jar (com.android.support:support-v4:22.2.0) 
Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules classes.jar (com.android.support:support-compat:27.1.1) and classes.jar (com.android.support:support-v4:22.2.0) 
Duplicate class android.support.v4.app.ListFragment found in modules classes.jar (com.android.support:support-fragment:27.1.1) and classes.jar (com.android.support:support-v4:22.2.0) 
Duplicate class android.support.v4.app.ListFragment$1 found in modules classes.jar (com.android.support:support-fragment:27.1.1) and classes.jar (com.android.support:support-v4:22.2.0) 
Duplicate class android.support.v4.app.ListFragment$2 found in modules classes.jar (com.android.support:support-fragment:27.1.1) and classes.jar (com.android.support:support-v4:22.2.0) 
Duplicate class android.support.v4.app.LoaderManager found in modules classes.jar (com.android.support:support-fragment:27.1.1) and classes.jar (com.android.support:support-v4:22.2.0) 

This is my app level build.gradle configuration:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "com.tototita.cxensetestapp"
        minSdkVersion 15
        targetSdkVersion 27
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }


    packagingOptions {
        exclude 'META-INF/LICENSE'
    }
    compileOptions {
        sourceCompatibility = '1.8'
        targetCompatibility = '1.8'
    }


}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.1' 
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

     //**CXsense
     implementation 'com.cxpublic:cxense-android:1.0.1'
}

How could I avoid this duplicated classes that are surely contained in Cxense SDK?

Answer 1

There are two ways to fix your issue.

1. Excluding duplicated dependencies while implementation individually,

2. Excluding duplicated dependencies from every implementations in generic way.

Let's first understand the problem :

Here, in your case artifact com.android.support is duplicated, because your app module uses version : 27.1.1 while your artifact com.cxpublic:cxense-android:1.0.1 is having internal dependency of com.android.support uses version : 22.2.0.

So, you should remove one of them manually (removing older or lower version is recommended). Let's try to remove it !

---

By first approach:

implementation ('com.cxpublic:cxense-android:1.0.1') {
    exclude group: "com.android.support", module: "support-v4"
}

Putting exclude for group com.android.support in our artifact com.cxpublic:cxense-android:1.0.1 will not get imported for support-v4 libraries when we use our implementation on this artifact.

So, issue would be resolved by manually putting this block to every artifact having this conflict.

By Second way:

We can remove included dependencies and replace them with one package with latest number. In our case, it is support-v4 with different version. So, go to the android block of app level build.gradle and put below block there to remove duplicated support-v4 from all artifacts, so that we can have distinct dependency.

android {
    // Some other stuffs
    configurations {
        all*.exclude module: 'support-v4' // This removes all other versions of `support-v4` if gets duplicated from all the artifacts.
    }
    // Rest of other stuffs
}

Answer 2

If there are duplicates, use exclude:

implementation ('com.cxpublic:cxense-android:1.0.1') {
    exclude group: "com.android.support", module: "support-v4"
}

Or remove implementation 'com.android.support:appcompat-v7:27.1.1' in favour of support-v4.

See: https://discuss.gradle.org/t/how-do-i-exclude-specific-transitive-dependencies-of-something-i-depend-on/17991