android - Multidex issue with Flutter

Question

I'm getting the following error compiling with gradle using Flutter in Android Studio:

Dex: Error converting bytecode to dex:
Cause: com.android.dex.DexException: Multiple dex files define Lcom/google/android/gms/internal/zzcew;
UNEXPECTED TOP-LEVEL EXCEPTION:
com.android.dex.DexException: Multiple dex files define Lcom/google/android/gms/internal/zzcew;

[... stacktrace omitted for brevity ...]

* What went wrong:
Execution failed for task ':app:transformDexArchiveWithDexMergerForDebug'.
> com.android.build.api.transform.TransformException: com.android.dex.DexException: Multiple dex files define Lcom/google/android/gms/internal/zzcew;

The short version

This only occurs if I add enough dependencies, as might be expected. I've enabled multidex and added the multidex dependency in the Android project build.gradle file as per instructions (https://developer.android.com/studio/build/multidex.html), but wasn't sure what to do about step 2 in "Configure your app for multidex" for a Flutter App, or even whether the omission of that step was the problem.

Steps to recreate:

1. Select File/New/New Flutter Project from the toolbar
2. Select "Flutter Application"
3. Include Kotlin & Swift support
4. Check the app compiles and runs

5. Add the following to dependencies in pubspec.yaml:

   dependencies:
     flutter_google_place_picker: "^0.0.1"
     location: "^1.2.0"
   

6. Hit Packages Get in Android Studio or run flutter packages get in the project directory

7. Modify android/app/build.gradle to add the following sections in the appropriate places:

   dependencies {
     compile 'com.android.support:multidex:1.0.1'
   }
   android {
       defaultConfig {
           multiDexEnabled true
       }
   }
   

8. Select Run/Run from the toolbar

Other things I've tried

1. Replacing the "compile" dependency in build.gradle with each of the following:

   compile 'com.android.support:multidex:1.0.3'
   implementation 'com.android.support:multidex:1.0.1'
   implementation 'com.android.support:multidex:1.0.3'
   

2. Following the multidex steps for each of my dependencies; i.e. modifying their build.gradle files, enabling multidex and adding the multidex dependency.

3. Modifying minSdkVersion to each of 21 and 27 in each of the build.gradle files for my project and its dependencies, and enabling multidex for them.
4. Enabling minifying for my project.
5. Replacing location: "^1.2.0" with geolocation: "^0.2.1"

6. Not enabling multidex at all (i.e. skipping step 7 of recreating). This results in the following error:

   FAILURE: Build failed with an exception.
   
   * What went wrong:
   Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
   > java.lang.RuntimeException: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex
   

Flutter doctor output

$ flutter doctor -v
[√] Flutter (Channel beta, v0.2.8, on Microsoft Windows [Version 10.0.16299.371], locale en-GB)
    ? Flutter version 0.2.8 at D:flutter
    ? Framework revision b397406561 (2 weeks ago), 2018-04-02 13:53:20 -0700
    ? Engine revision c903c217a1
    ? Dart version 2.0.0-dev.43.0.flutter-52afcba357

[√] Android toolchain - develop for Android devices (Android SDK 27.0.3)
    ? Android SDK at C:UsersDaveAppDataLocalAndroidsdk
    ? Android NDK location not configured (optional; useful for native profiling support)
    ? Platform android-27, build-tools 27.0.3
    ? Java binary at: D:AndroidDevjreinjava
    ? Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b02)
    ? All Android licenses accepted.

[√] Android Studio (version 3.1)
    ? Android Studio at D:AndroidDev
    ? Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b02)

[√] Connected devices (1 available)
    ? Android SDK built for x86 64 ? emulator-5554 ? android-x64 ? Android 5.1.1 (API 22) (emulator)

? No issues found!

Answer 1

If you don't have experience with developing android application this information can be helpful otherwise you won't find anything new.

---

In most cases, enough will do the first step

How to enable multidex for flutter project.

1. Enable multidex.

Open [project_folder]/app/build.gradle and add following lines.

defaultConfig {
    ...

    multiDexEnabled true
}

and

dependencies {
    ...

    implementation 'com.android.support:multidex:1.0.3'
}

2. Enable Jetifier.

Open [project_folder]/android/app/gradle.properties and add following lines.

android.useAndroidX=true
android.enableJetifier=true

NOTE: As of flutter 1.7, the below steps are no longer necessary.

---

3) **Create custom application class.**

If you don't know where to create the file do it near MainActivity for example [project_folder]/android/app/src/main/kotlin(or java if you didn't enable kotlin)/your/great/pakage/appname/

kotlin example: App.kt

    package your.great.pakage.appname
    
    import io.flutter.app.FlutterApplication
    import android.content.Context
    import androidx.multidex.MultiDex
    
    class App : FlutterApplication() {
    
        override fun attachBaseContext(base: Context) {
            super.attachBaseContext(base)
            MultiDex.install(this)
        }
    
    }

java example: App.java

    package your.great.pakage.appname;
    
    import io.flutter.app.FlutterApplication;
    import android.content.Context;
    import androidx.multidex.MultiDex;

    public class App extends FlutterApplication {

        @Override
        protected void attachBaseContext(Context base) {
            super.attachBaseContext(base);
            MultiDex.install(this);
        }

    }

4. Change the default application file to new.

Open [project_folder]/android/app/src/main/AndroidManifest.xml

Change android:name="io.flutter.app.FlutterApplication" to android:name=".App"