Android - Supertypes of the following classes can not be resolved - (Room Persistant Library, Android Library Module)

Question

In my Android project (Kotlin), I want to use Room persistent library for my DATA LAYER.

But when I added dependencies for Room Persistent library suddenly build projects start failing.

Error which I am receiving:

Here is my project level build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    ext {
        globalCompileSdkVersion = 26
        globalMinSdkVersion = 19
        globalTargetSdkVersion = 26

        kotlin_version = '1.2.10'
        support_version = "27.0.2"
        constraint_layout_version = "1.0.2"
        view_animator_version = "1.0.5"
        junit_version = "4.12"
        runner_version = "1.0.1"
        espresso_core_version = "3.0.1"
        room_version = "1.0.0"
        dagger_version = "2.13"
        rxJavaVersion = "2.1.7"
        rxAndroidVersion = "2.0.1"

        libs = [
                appCompatV7 : "com.android.support:appcompat-v7:$support_version",
                rxJava      : "io.reactivex.rxjava2:rxjava:$rxJavaVersion",
                rxAndroid   : "io.reactivex.rxjava2:rxandroid:$rxAndroidVersion",
                junit       : "junit:junit:$junit_version",
                runner      : "com.android.support.test:runner:$runner_version",
                espressoCore: "com.android.support.test.espresso:espresso-core:$espresso_core_version"
        ]
    }

    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Here is my app module build.gradle

apply plugin: 'com.android.application'
apply plugin: 'kotlin-kapt'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'

android {
    compileSdkVersion project.globalCompileSdkVersion
    defaultConfig {
        applicationId "com.keepsafe.app"
        minSdkVersion project.globalMinSdkVersion
        targetSdkVersion project.globalTargetSdkVersion
        versionCode 1
        versionName "1.0"

        vectorDrawables.useSupportLibrary = true
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation libs.appCompatV7
    implementation "com.android.support:design:$support_version"
    implementation "com.android.support.constraint:constraint-layout:$constraint_layout_version"
    implementation "com.github.florent37:viewanimator:$view_animator_version"
    implementation "com.google.dagger:dagger:$dagger_version"
    kapt "com.google.dagger:dagger-compiler:$dagger_version"
    implementation libs.rxJava
    implementation libs.rxAndroid
    testImplementation libs.junit
    androidTestImplementation libs.runner
    androidTestImplementation libs.espressoCore

    implementation project(":data")
    implementation project(":domain")
}

Here is my domain module build.gradle

apply plugin: 'java-library'
apply plugin: 'kotlin'

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation libs.rxJava
    implementation libs.rxAndroid
    implementation libs.junit
}

sourceCompatibility = "1.7"
targetCompatibility = "1.7"

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}
compileKotlin {
    kotlinOptions {
        jvmTarget = "1.8"
    }
}
compileTestKotlin {
    kotlinOptions {
        jvmTarget = "1.8"
    }
}

Here is my data module build.gradle

apply plugin: 'com.android.library'
apply plugin: 'kotlin-kapt'
apply plugin: 'kotlin-android'

android {
    compileSdkVersion project.globalCompileSdkVersion
    defaultConfig {
        minSdkVersion project.globalMinSdkVersion
        targetSdkVersion project.globalTargetSdkVersion
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }

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

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation "android.arch.persistence.room:runtime:$room_version"
    implementation "android.arch.persistence.room:rxjava2:$room_version"
    kapt "android.arch.persistence.room:compiler:$room_version"
    testImplementation libs.junit

    implementation project(":domain")
}
repositories {
    mavenCentral()
}

I don't know how to resolve this issue.

Your help will be appreciated.

Answer 1

Android Gradle Plugin 3.0 and higher added a new behaviour for dependencies. You can read more about this here. Long story short, by using implementation in a submodule you're not sharing a dependency with a consumer module(your app module). Thus, it's not possible to generate the code needed for Room.

Essentially, what you need to do is simply change implementation to api in your data module for the Room's dependencies. The result will be:

api "android.arch.persistence.room:runtime:$room_version"
api "android.arch.persistence.room:rxjava2:$room_version"