Can’t import MultiDexApplication

I have an app built with react native and I need to enable MultiDexsupport. My problem is that I can’t import the MultiDexApplication class to extend it because at compile time I get symbol not found error for both the import statement and the class name when extending it in MainApplication.java

build.gradle

    dependencies {
        classpath('com.android.tools.build:gradle:3.5.3')
        classpath 'com.google.gms:google-services:4.2.0'
        classpath "androidx.multidex:multidex:2.0.1"

    }

If I try to add the dependency as implementation, I get the following error when starting the app:

Could not find method implementation() for arguments [androidx.multidex:multidex:2.0.1] on object of type org.gradle.api.internal.artifacts.dsl.dependencies.DefaultDependencyHandler.

In all online resources I saw that the dependecy was added as implementation so I guess that can be my problem.

MainApplication.java

package com.classmanager;

import android.app.Application;
import androidx.multidex.MultiDexApplication;
import android.content.Context;
import com.facebook.react.PackageList;
import com.facebook.react.ReactApplication;
import com.oblador.vectoricons.VectorIconsPackage;
import com.oblador.vectoricons.VectorIconsPackage;
import com.facebook.react.ReactNativeHost;
import com.facebook.react.ReactPackage;
import com.facebook.soloader.SoLoader;
import java.lang.reflect.InvocationTargetException;
import java.util.List;

public class MainApplication extends MultiDexApplication  implements ReactApplication {
  private final ReactNativeHost mReactNativeHost =
      new ReactNativeHost(this) {
        @Override
        public boolean getUseDeveloperSupport() {
          return BuildConfig.DEBUG;
        }

        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          // Packages that cannot be autolinked yet can be added manually here, for example:
          // packages.add(new MyReactNativePackage());
          return packages;
        }

        @Override
        protected String getJSMainModuleName() {
          return "index";
        }
      };

  @Override
  public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
  }

  @Override
  public void onCreate() {
    super.onCreate();
    SoLoader.init(this, /* native exopackage */ false);
    initializeFlipper(this); // Remove this line if you don't want Flipper enabled
  }

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

  /**
   * Loads Flipper in React Native templates.
   *
   * @param context
   */
  private static void initializeFlipper(Context context) {
    if (BuildConfig.DEBUG) {
      try {
        /*
         We use reflection here to pick up the class that initializes Flipper,
        since Flipper library is not available in release mode
        */
        Class<?> aClass = Class.forName("com.facebook.flipper.ReactNativeFlipper");
        aClass.getMethod("initializeFlipper", Context.class).invoke(null, context);
      } catch (ClassNotFoundException e) {
        e.printStackTrace();
      } catch (NoSuchMethodException e) {
        e.printStackTrace();
      } catch (IllegalAccessException e) {
        e.printStackTrace();
      } catch (InvocationTargetException e) {
        e.printStackTrace();
      }
    }
  }
}

It’s the default MainApplication from react-native init, except that I imported the MultiDexApplication class and extended it instead of Application. But when I run the app, I get the following error:

    import androidx.multidex.MultiDexApplication;
                        ^
  symbol:   class MultiDexApplication
  location: package androidx.multidex
C:UsersmeadiWebstormProjectsClassManagerandroidappsrcmainjavacomclassmanagerMainApplication.java:16: error: cannot find symbol
public class MainApplication extends MultiDexApplication  implements ReactApplication {
                                     ^
  symbol: class MultiDexApplication
C:UsersmeadiWebstormProjectsClassManagerandroidappsrcmainjavacomclassmanagerMainApplication.java:18: error: incompatible types: MainApplication cannot be converted to Application
      new ReactNativeHost(this) {
                          ^

Any idea why MultiDexApplication couldn’t be resolved?

update: I tried adding the multidex dependecy as implementation to the app level build.gradle. It seems now that the class is resolved, but i get this error:

    D8: Cannot fit requested classes in a single dex file (# methods: 100718 > 65536)
com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives:
The number of method references in a .dex file cannot exceed 64K.

So MultiDex is still not enabled

Update: Here is the project level build.gradle

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

buildscript {
    ext {
        buildToolsVersion = "28.0.3"
        minSdkVersion = 16
        compileSdkVersion = 28
        targetSdkVersion = 28
         multiDexEnabled = true
    }
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath('com.android.tools.build:gradle:3.5.3')
        classpath 'com.google.gms:google-services:4.2.0'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        mavenLocal()
        maven {
            // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
            url("$rootDir/../node_modules/react-native/android")
        }
        maven {
            // Android JSC is installed from npm
            url("$rootDir/../node_modules/jsc-android/dist")
        }

        google()
        jcenter()
        maven { url 'https://jitpack.io' }
    }
}

And here is the app level build.gradle

apply plugin: "com.android.application"

import com.android.build.OutputFile

project.ext.react = [
        entryFile   : "index.js",
        enableHermes: false,  // clean and rebuild if changing
]

apply from: "../../node_modules/react-native/react.gradle"

/**
 * Set this to true to create two separate APKs instead of one:
 *   - An APK that only works on ARM devices
 *   - An APK that only works on x86 devices
 * The advantage is the size of the APK is reduced by about 4MB.
 * Upload all the APKs to the Play Store and people will download
 * the correct one based on the CPU architecture of their device.
 */
def enableSeparateBuildPerCPUArchitecture = false

/**
 * Run Proguard to shrink the Java bytecode in release builds.
 */
def enableProguardInReleaseBuilds = false

/**
 * The preferred build flavor of JavaScriptCore.
 *
 * For example, to use the international variant, you can use:
 * `def jscFlavor = 'org.webkit:android-jsc-intl:+'`
 *
 * The international variant includes ICU i18n library and necessary data
 * allowing to use e.g. `Date.toLocaleString` and `String.localeCompare` that
 * give correct results when using with locales other than en-US.  Note that
 * this variant is about 6MiB larger per architecture than default.
 */
def jscFlavor = 'org.webkit:android-jsc:+'

/**
 * Whether to enable the Hermes VM.
 *
 * This should be set on project.ext.react and mirrored here.  If it is not set
 * on project.ext.react, JavaScript will not be compiled to Hermes Bytecode
 * and the benefits of using Hermes will therefore be sharply reduced.
 */
def enableHermes = project.ext.react.get("enableHermes", false);

android {
    compileSdkVersion rootProject.ext.compileSdkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    defaultConfig {
        applicationId "com.classmanager"
        minSdkVersion rootProject.ext.minSdkVersion
        targetSdkVersion rootProject.ext.targetSdkVersion
        versionCode 1
        versionName "1.0"
    }
    splits {
        abi {
            reset()
            enable enableSeparateBuildPerCPUArchitecture
            universalApk false  // If true, also generate a universal APK
            include "armeabi-v7a", "x86", "arm64-v8a", "x86_64"
        }
    }
    signingConfigs {
        debug {
            storeFile file('debug.keystore')
            storePassword 'android'
            keyAlias 'androiddebugkey'
            keyPassword 'android'
        }
    }
    buildTypes {
        debug {
            signingConfig signingConfigs.debug
        }
        release {
            // Caution! In production, you need to generate your own keystore file.
            // see https://facebook.github.io/react-native/docs/signed-apk-android.
            signingConfig signingConfigs.debug
            minifyEnabled enableProguardInReleaseBuilds
            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
        }
    }
    // applicationVariants are e.g. debug, release
    applicationVariants.all { variant ->
        variant.outputs.each { output ->
            // For each separate APK per architecture, set a unique version code as described here:
            // https://developer.android.com/studio/build/configure-apk-splits.html
            def versionCodes = ["armeabi-v7a": 1, "x86": 2, "arm64-v8a": 3, "x86_64": 4]
            def abi = output.getFilter(OutputFile.ABI)
            if (abi != null) {  // null for the universal-debug, universal-release variants
                output.versionCodeOverride =
                        versionCodes.get(abi) * 1048576 + defaultConfig.versionCode
            }

        }
    }
}

dependencies {

    implementation project (':react-native-vector-icons')
    implementation 'com.google.firebase:firebase-analytics:17.2.0'
    implementation 'androidx.appcompat:appcompat:1.1.0-rc01'
    implementation 'androidx.swiperefreshlayout:swiperefreshlayout:1.1.0-alpha02'
    implementation fileTree(dir: "libs", include: ["*.jar"])
    implementation 'androidx.multidex:multidex:2.0.1'
    implementation "com.facebook.react:react-native:+"  // From node_modules

    if (enableHermes) {
        def hermesPath = "../../node_modules/hermes-engine/android/";
        debugImplementation files(hermesPath + "hermes-debug.aar")
        releaseImplementation files(hermesPath + "hermes-release.aar")
    } else {
        implementation jscFlavor
    }
}

// Run this once to be able to run the application with BUCK
// puts all compile dependencies into folder libs for BUCK to use
task copyDownloadableDepsToLibs(type: Copy) {
    from configurations.compile
    into 'libs'
}

apply from: file("../../node_modules/@react-native-community/cli-platform-android/native_modules.gradle"); applyNativeModulesAppBuildGradle(project)
apply plugin: 'com.google.gms.google-services'

Source: React natvie