"Duplicate class javax.inject.*" build error when Firebase Crashlytics is added to Android

Question

I am trying to add Firebase Crashlytics to my project. I am getting the below error.

Duplicate class javax.inject.Inject found in modules javax.inject-1.jar (javax.inject:javax.inject:1) and jetified-roboguice-3.0.1.jar (org.roboguice:roboguice:3.0.1)
Duplicate class javax.inject.Named found in modules javax.inject-1.jar (javax.inject:javax.inject:1) and jetified-roboguice-3.0.1.jar (org.roboguice:roboguice:3.0.1)
Duplicate class javax.inject.Provider found in modules javax.inject-1.jar (javax.inject:javax.inject:1) and jetified-roboguice-3.0.1.jar (org.roboguice:roboguice:3.0.1)
Duplicate class javax.inject.Qualifier found in modules javax.inject-1.jar (javax.inject:javax.inject:1) and jetified-roboguice-3.0.1.jar (org.roboguice:roboguice:3.0.1)
Duplicate class javax.inject.Scope found in modules javax.inject-1.jar (javax.inject:javax.inject:1) and jetified-roboguice-3.0.1.jar (org.roboguice:roboguice:3.0.1)
Duplicate class javax.inject.Singleton found in modules javax.inject-1.jar (javax.inject:javax.inject:1) and jetified-roboguice-3.0.1.jar (org.roboguice:roboguice:3.0.1)

Go to the documentation to learn how to Fix dependency resolution errors.

Project level build.gradle:

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

buildscript {
    repositories {
        jcenter()
        google()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.5.0'
        classpath 'com.google.gms:google-services:4.3.5'
        classpath 'com.google.firebase:firebase-crashlytics-gradle:2.5.1'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

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

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

App level build.gradle:

apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
apply plugin: 'com.google.firebase.crashlytics'

android {
    compileSdkVersion 29
    buildToolsVersion "29.0.3"

    defaultConfig {
        applicationId "package.name"
        minSdkVersion 21
        targetSdkVersion 29
        versionCode 26
        versionName "1.4.1"
        javaCompileOptions {
            annotationProcessorOptions {
                includeCompileClasspath true
            }
        }
        buildConfigField "long", "TIMESTAMP", System.currentTimeMillis() + "L"

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

    lintOptions {
        checkReleaseBuilds true
        // Or, if you prefer, you can continue to check for errors in release builds,
        // but continue the build even when errors are found:
        abortOnError false
    }

}

project.tasks.withType(JavaCompile) { task ->
    options.compilerArgs << "-AguiceAnnotationDatabasePackageName=package"
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    testImplementation 'junit:junit:4.12'
    testImplementation project(':module1')
    testImplementation 'org.mockito:mockito-core:1.+'
    testImplementation('org.robolectric:robolectric:3.1-rc1') {
        exclude group: 'commons-logging', module: 'commons-logging'
        exclude group: 'org.apache.httpcomponents', module: 'httpclient'
    }
    implementation project(':module1')
    implementation project(':module2')
    implementation project(':roboguicehelper')
    compileOnly 'org.roboguice:roboblender:3.+'
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'org.roboguice:roboguice:3.+'
    implementation 'com.google.android.material:material:1.0.0'
    //noinspection GradleCompatible
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation project(':module4')

    implementation platform('com.google.firebase:firebase-bom:26.6.0')
    implementation 'com.google.firebase:firebase-analytics'
    implementation 'com.google.firebase:firebase-crashlytics'
}

If I remove this -> implementation 'com.google.firebase:firebase-crashlytics' the project builds and runs fine. But I need to add Crashlytics.

Gradle version is gradle-5.6.4

Any Suggestions?

Answer 1

From the below image, we can see that the roboguice library already has the java.inject library inside it. And with that, Firebase Crashlytics adds java.inject:java.inject:1@jar to the libraries which caused the error.

Changing the below line in App level build.gradle from

implementation 'com.google.firebase:firebase-crashlytics'

to

implementation ('com.google.firebase:firebase-crashlytics') {
    exclude module: "javax.inject"
}

fixed the error.