Android Gradle DexException: Multiple dex files define Lorg/hamcrest/Description

Question

com.android.dex.DexException: Multiple dex files define Lorg/hamcrest/Description

occurring while trying to do a debug build/test either via Android Studio or via Gradle command-line on my application.

The release build (without tests) works fine but as soon as testing is included (hamcrest being a testing library), the build fails with the above error.

I've checked my module dependencies and there's no duplicate requirements which gradle -q dependencies corroborates.

---

Project settings.gradle

include ':[library module]'
include ':[main module]'

---

Project build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.9.+'
        classpath 'org.robolectric.gradle:gradle-android-test-plugin:0.9.+'
    }
}

allprojects {
    repositories {
        mavenCentral()
    }
}

---

[library module] build.gradle

apply plugin: 'android-library'

android {
    compileSdkVersion 19
    buildToolsVersion "19.0.0"

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 19
    }

    packagingOptions {
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
    }
}

dependencies {
    compile 'com.google.zxing:core:3.0.+'
    compile 'com.bugsnag:bugsnag-android:2.1.1+'
}

---

[main module] build.gradle

apply plugin: 'android'

android {
    signingConfigs {
    release {
        [...]
    }
}

    sourceSets {
        main {
            manifest.srcFile 'src/main/AndroidManifest.xml'
            res.srcDirs = ['src/main/res']
        }
        androidTest {
            setRoot('src/test')
        }
        instrumentTest {
        }
    }

    compileSdkVersion 19
    buildToolsVersion '19.0.0'

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 19
        testPackageName "[main.packageName].tests"
    }

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

    packagingOptions {
        exclude 'META-INF/LICENSE.txt'
        exclude 'META-INF/NOTICE.txt'
    }
}

apply plugin: 'android-test'



androidTest {
    // configure the set of classes for JUnit tests
    include '**/*Test.class'

    // configure max heap size of the test JVM
    maxHeapSize = "2048m"
}

repositories {
    maven { url 'https://repo.commonsware.com.s3.amazonaws.com' }
    maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
}

dependencies {
    androidTestCompile 'junit:junit:4.10'
    androidTestCompile 'org.robolectric:robolectric:2.3-SNAPSHOT'
    androidTestCompile 'com.squareup:fest-android:1.0.+'
    compile project(':[library module]')
    compile 'com.github.gabrielemariotti.changeloglib:library:1.4.+'
    compile 'com.google.code.gson:gson:2.2.4'
    compile 'com.google.android.gms:play-services:+'
    compile 'com.android.support:appcompat-v7:+'
    compile ('de.keyboardsurfer.android.widget:crouton:1.8.+') {
        exclude group: 'com.google.android', module: 'support-v4'
    }
    compile files('libs/CWAC-LoaderEx.jar')
    compile 'com.squareup.okhttp:okhttp:1.5.+'
    compile 'com.octo.android.robospice:robospice:1.4.11'
    compile 'com.octo.android.robospice:robospice-cache:1.4.11'
    compile 'com.octo.android.robospice:robospice-retrofit:1.4.11'
    compile 'com.commonsware.cwac:security:0.1.+'
    compile 'com.readystatesoftware.sqliteasset:sqliteassethelper:+'
}

Answer 1

Robolectric 2.3 depends on JUnit 4.8.1 (version explicit). You're importing JUnit 4.10 (version explicit). Hamcrest is probably simply the first of many duplicates that dex is choking on - try changing your JUnit requirement version to 4.8+ (or excluding JUnit from the Robolectric dependency).

Answer 2

I solved the error by looking in Android Studio for the exact class called 'Description'. It turned out to be present in 3 jars. One from junit, one from a direct dependency and one from mockito.

It turns out that junit, instead of a normal dependency, includes the Hamcrest classes in the junit jar.

To be able to solve the problem include junit-dep instead of junit.

so change

androidTestCompile('junit:junit:4.8.+')

to

androidTestCompile('junit:junit-dep:4.8.+')

Mockito has the same problem/solution: use mockito-core.1.9.5.jar instead of mockito-all.1.9.5.jar

Answer 3

My project had a dependency on json-simple version 1.1.1, which for some reason has a run-time dependency on junit version 4.1.0, which itself has a dependency on Hamcrest. I could see this if I ran gradle dependencies or alternatively by inspecting the json-simple POM.xml.

// compile - Classpath for compiling the main sources.
    \--- com.googlecode.json-simple:json-simple:1.1.1
         \--- junit:junit:4.10
              \--- org.hamcrest:hamcrest-core:1.1

Excluding the junit artifact from json-simple allowed me to build.

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile ('com.googlecode.json-simple:json-simple:1.1.1') {
        exclude module: 'junit'
    }
}

Answer 4

exclude module: junit

if you are using json:simple dependency