Add multidex flag and automatic multidex support (#90944)

packages/flutter_tools/gradle/flutter.gradle

@@ -215,6 +215,38 @@ class FlutterPlugin implements Plugin<Project> {
             }
         }
 
+        if (project.hasProperty("multidex-enabled") &&
+            project.property("multidex-enabled").toBoolean() &&
+            project.android.defaultConfig.minSdkVersion <= 20) {
+            String flutterMultidexKeepfile = Paths.get(flutterRoot.absolutePath, "packages", "flutter_tools",
+                "gradle", "flutter_multidex_keepfile.txt")
+            project.android {
+                defaultConfig {
+                    multiDexEnabled true
+                    manifestPlaceholders = [applicationName: "io.flutter.app.FlutterMultiDexApplication"]
+                }
+                buildTypes {
+                    release {
+                        multiDexKeepFile project.file(flutterMultidexKeepfile)
+                    }
+                }
+            }
+            project.dependencies {
+                implementation "androidx.multidex:multidex:2.0.1"
+            }
+        } else {
+            String baseApplicationName = "android.app.Application"
+            if (project.hasProperty("base-application-name")) {
+                baseApplicationName = project.property("base-application-name")
+            }
+            project.android {
+                defaultConfig {
+                    // Setting to android.app.Application is the same as omitting the attribute.
+                    manifestPlaceholders = [applicationName: baseApplicationName]
+                }
+            }
+        }
+
         if (useLocalEngine()) {
             // This is required to pass the local engine to flutter build aot.
             String engineOutPath = project.property('local-engine-out')

packages/flutter_tools/gradle/flutter_multidex_keepfile.txt

+io/flutter/app/FlutterApplication.class
+io/flutter/app/FlutterMultiDexApplication.class
+io/flutter/embedding/engine/loader/FlutterLoader.class
+io/flutter/view/FlutterMain.class
+io/flutter/util/PathUtils.class

packages/flutter_tools/lib/src/android/android_device.dart

@@ -595,7 +595,8 @@ class AndroidDevice extends Device {
           androidBuildInfo: AndroidBuildInfo(
             debuggingOptions.buildInfo,
             targetArchs: <AndroidArch>[androidArch],
-            fastStart: debuggingOptions.fastStart
+            fastStart: debuggingOptions.fastStart,
+            multidexEnabled: platformArgs['multidex'] as bool,
           ),
       );
       // Package has been built, so we can get the updated application ID and

packages/flutter_tools/lib/src/android/gradle.dart

@@ -28,6 +28,7 @@ import 'android_builder.dart';
 import 'android_studio.dart';
 import 'gradle_errors.dart';
 import 'gradle_utils.dart';
+import 'multidex.dart';
 
 /// The directory where the APK artifact is generated.
 Directory getApkDirectory(FlutterProject project) {
@@ -293,6 +294,22 @@ class AndroidGradleBuilder implements AndroidBuilder {
     if (target != null) {
       command.add('-Ptarget=$target');
     }
+    // Only attempt adding multidex support if all the flutter generated files exist.
+    // If the files do not exist and it was unintentional, the app will fail to build
+    // and prompt the developer if they wish Flutter to add the files again via gradle_error.dart.
+    if (androidBuildInfo.multidexEnabled &&
+        multiDexApplicationExists(project.directory) &&
+        androidManifestHasNameVariable(project.directory)) {
+      command.add('-Pmultidex-enabled=true');
+      ensureMultiDexApplicationExists(project.directory);
+      _logger.printStatus('Building with Flutter multidex support enabled.');
+    }
+    // If using v1 embedding, we want to use FlutterApplication as the base app.
+    final String baseApplicationName =
+        project.android.getEmbeddingVersion() == AndroidEmbeddingVersion.v2 ?
+          'android.app.Application' :
+          'io.flutter.app.FlutterApplication';
+    command.add('-Pbase-application-name=$baseApplicationName');
     final List<DeferredComponent>? deferredComponents = project.manifest.deferredComponents;
     if (deferredComponents != null) {
       if (deferredComponentsEnabled) {
@@ -389,6 +406,7 @@ class AndroidGradleBuilder implements AndroidBuilder {
           line: detectedGradleErrorLine!,
           project: project,
           usesAndroidX: usesAndroidX,
+          multidexEnabled: androidBuildInfo.multidexEnabled,
         );
 
         if (retries >= 1) {

packages/flutter_tools/lib/src/android/gradle_errors.dart

@@ -7,10 +7,12 @@ import 'package:meta/meta.dart';
 import '../base/error_handling_io.dart';
 import '../base/file_system.dart';
 import '../base/process.dart';
+import '../base/terminal.dart';
 import '../globals_null_migrated.dart' as globals;
 import '../project.dart';
 import '../reporting/reporting.dart';
 import 'android_studio.dart';
+import 'multidex.dart';
 
 typedef GradleErrorTest = bool Function(String);
 
@@ -31,6 +33,7 @@ class GradleHandledError {
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) handler;
 
   /// The [BuildEvent] label is named gradle-[eventLabel].
@@ -71,8 +74,104 @@ final List<GradleHandledError> gradleErrors = <GradleHandledError>[
   minSdkVersion,
   transformInputIssue,
   lockFileDepMissing,
+  multidexErrorHandler,
 ];
 
+// Multidex error message.
+@visibleForTesting
+final GradleHandledError multidexErrorHandler = GradleHandledError(
+  test: _lineMatcher(const <String>[
+    'com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives:',
+    'The number of method references in a .dex file cannot exceed 64K.',
+  ]),
+  handler: ({
+    required String line,
+    required FlutterProject project,
+    required bool usesAndroidX,
+    required bool multidexEnabled,
+  }) async {
+    globals.printStatus('${globals.logger.terminal.warningMark} App requires Multidex support', emphasis: true);
+    if (multidexEnabled) {
+      globals.printStatus(
+        'Multidex support is required for your android app to build since the number of methods has exceeded 64k. '
+        "You may pass the --no-multidex flag to skip Flutter's multidex support to use a manual solution.\n",
+        indent: 4,
+      );
+      if (!androidManifestHasNameVariable(project.directory)) {
+        globals.printStatus(
+          r'Your `android/app/src/main/AndroidManifest.xml` does not contain `android:name="${applicationName}"` '
+          'under the `application` element. This may be due to creating your project with an old version of Flutter. '
+          'Add the `android:name="\${applicationName}"` attribute to your AndroidManifest.xml to enable Flutter\'s multidex support:\n',
+          indent: 4,
+        );
+        globals.printStatus(r'''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  ...
+  <application
+    ...
+    android:name=''',
+          indent: 8,
+          newline: false,
+          color: TerminalColor.grey,
+        );
+        globals.printStatus(r'"${applicationName}"', color: TerminalColor.green, newline: true);
+        globals.printStatus(r'''
+    ...>
+''',
+          indent: 8,
+          color: TerminalColor.grey,
+        );
+
+        globals.printStatus(
+          'You may also roll your own multidex support by following the guide at: https://developer.android.com/studio/build/multidex\n',
+          indent: 4,
+        );
+        return GradleBuildStatus.exit;
+      }
+      if (!multiDexApplicationExists(project.directory)) {
+        globals.printStatus(
+          'Flutter tool can add multidex support. The following file will be added by flutter:\n',
+          indent: 4,
+        );
+        globals.printStatus(
+          'android/app/src/main/java/io/flutter/app/FlutterMultiDexApplication.java\n',
+          indent: 8,
+        );
+        String selection = 'n';
+        // Default to 'no' if no interactive terminal.
+        try {
+          selection = await globals.terminal.promptForCharInput(
+            <String>['y', 'n'],
+            logger: globals.logger,
+            prompt: 'Do you want to continue with adding multidex support for Android?',
+            defaultChoiceIndex: 0,
+          );
+        } on StateError catch(e) {
+          globals.printError(
+            e.message,
+            indent: 0,
+          );
+        }
+        if (selection == 'y') {
+          ensureMultiDexApplicationExists(project.directory);
+          globals.printStatus(
+            'Multidex enabled. Retrying build.\n',
+            indent: 0,
+          );
+          return GradleBuildStatus.retry;
+        }
+      }
+    } else {
+      globals.printStatus(
+        'Flutter multidex handling is disabled. If you wish to let the tool configure multidex, use the --mutidex flag.',
+        indent: 4,
+      );
+    }
+    return GradleBuildStatus.exit;
+  },
+  eventLabel: 'multidex-error',
+);
+
 // Permission defined error message.
 @visibleForTesting
 final GradleHandledError permissionDeniedErrorHandler = GradleHandledError(
@@ -83,12 +182,13 @@ final GradleHandledError permissionDeniedErrorHandler = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     globals.printStatus('${globals.logger.terminal.warningMark} Gradle does not have execution permission.', emphasis: true);
     globals.printStatus(
       'You should change the ownership of the project directory to your user, '
       'or move the project to a directory with execute permissions.',
-      indent: 4
+      indent: 4,
     );
     return GradleBuildStatus.exit;
   },
@@ -119,6 +219,7 @@ final GradleHandledError networkErrorHandler = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     globals.printError(
       '${globals.logger.terminal.warningMark} Gradle threw an error while downloading artifacts from the network. '
@@ -148,6 +249,7 @@ final GradleHandledError r8FailureHandler = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     globals.printStatus('${globals.logger.terminal.warningMark} The shrinker may have failed to optimize the Java bytecode.', emphasis: true);
     globals.printStatus('To disable the shrinker, pass the `--no-shrink` flag to this command.', indent: 4);
@@ -169,6 +271,7 @@ final GradleHandledError licenseNotAcceptedHandler = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     const String licenseNotAcceptedMatcher =
       r'You have not accepted the license agreements of the following SDK components:\s*\[(.+)\]';
@@ -202,6 +305,7 @@ final GradleHandledError flavorUndefinedHandler = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     final RunResult tasksRunResult = await globals.processUtils.run(
       <String>[
@@ -274,6 +378,7 @@ final GradleHandledError minSdkVersion = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     final File gradleFile = project.directory
         .childDirectory('android')
@@ -314,6 +419,7 @@ final GradleHandledError transformInputIssue = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     final File gradleFile = project.directory
         .childDirectory('android')
@@ -347,6 +453,7 @@ final GradleHandledError lockFileDepMissing = GradleHandledError(
     required String line,
     required FlutterProject project,
     required bool usesAndroidX,
+    required bool multidexEnabled,
   }) async {
     final File gradleFile = project.directory
         .childDirectory('android')

packages/flutter_tools/lib/src/android/multidex.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:xml/xml.dart';
+
+import '../base/file_system.dart';
+
+// These utility methods are used to generate the code for multidex support as
+// well as verifying the project is properly set up.
+
+File _getMultiDexApplicationFile(Directory projectDir) {
+  return projectDir.childDirectory('android')
+    .childDirectory('app')
+    .childDirectory('src')
+    .childDirectory('main')
+    .childDirectory('java')
+    .childDirectory('io')
+    .childDirectory('flutter')
+    .childDirectory('app')
+    .childFile('FlutterMultiDexApplication.java');
+}
+
+/// Creates the FlutterMultiDexApplication.java if it does not exist.
+void ensureMultiDexApplicationExists(final Directory projectDir) {
+  final File applicationFile = _getMultiDexApplicationFile(projectDir);
+  if (applicationFile.existsSync()) {
+    return;
+  }
+  applicationFile.createSync(recursive: true);
+
+  final StringBuffer buffer = StringBuffer();
+  buffer.write('''
+// Generated file.
+// If you wish to remove Flutter's multidex support, delete this entire file.
+
+package io.flutter.app;
+
+import android.content.Context;
+import androidx.annotation.CallSuper;
+import androidx.multidex.MultiDex;
+
+/**
+ * Extension of {@link io.flutter.app.FlutterApplication}, adding multidex support.
+ */
+public class FlutterMultiDexApplication extends FlutterApplication {
+  @Override
+  @CallSuper
+  protected void attachBaseContext(Context base) {
+    super.attachBaseContext(base);
+    MultiDex.install(this);
+  }
+}
+''');
+  applicationFile.writeAsStringSync(buffer.toString(), flush: true);
+}
+
+/// Returns true if FlutterMultiDexApplication.java exists.
+///
+/// This function does not verify the contents of the file.
+bool multiDexApplicationExists(final Directory projectDir) {
+  if (_getMultiDexApplicationFile(projectDir).existsSync()) {
+    return true;
+  }
+  return false;
+}
+
+File _getManifestFile(Directory projectDir) {
+  return projectDir.childDirectory('android')
+    .childDirectory('app')
+    .childDirectory('src')
+    .childDirectory('main')
+    .childFile('AndroidManifest.xml');
+}
+
+/// Returns true if the `app` module AndroidManifest.xml includes the
+/// <application android:name="${applicationName}"> attribute.
+bool androidManifestHasNameVariable(final Directory projectDir) {
+  final File manifestFile = _getManifestFile(projectDir);
+  if (!manifestFile.existsSync()) {
+    return false;
+  }
+  XmlDocument document;
+  try {
+    document = XmlDocument.parse(manifestFile.readAsStringSync());
+  } on XmlParserException {
+    return false;
+  } on FileSystemException {
+    return false;
+  }
+  // Check for the ${androidName} application attribute.
+  for (final XmlElement application in document.findAllElements('application')) {
+    final String? applicationName = application.getAttribute('android:name');
+    if (applicationName == r'${applicationName}') {
+      return true;
+    }
+  }
+  return false;
+}

packages/flutter_tools/lib/src/build_info.dart

@@ -304,6 +304,7 @@ class AndroidBuildInfo {
     ],
     this.splitPerAbi = false,
     this.fastStart = false,
+    this.multidexEnabled = false,
   });
 
   // The build info containing the mode and flavor.
@@ -321,6 +322,9 @@ class AndroidBuildInfo {
 
   /// Whether to bootstrap an empty application.
   final bool fastStart;
+
+  /// Whether to enable multidex support for apps with more than 64k methods.
+  final bool multidexEnabled;
 }
 
 /// A summary of the compilation strategy used for Dart.

packages/flutter_tools/lib/src/commands/build_apk.dart

@@ -35,6 +35,7 @@ class BuildApkCommand extends BuildSubCommand {
     addNullSafetyModeOptions(hide: !verboseHelp);
     usesAnalyzeSizeFlag();
     addAndroidSpecificBuildOptions(hide: !verboseHelp);
+    addMultidexOption();
     argParser
       ..addFlag('split-per-abi',
         negatable: false,
@@ -99,9 +100,11 @@ class BuildApkCommand extends BuildSubCommand {
       buildInfo,
       splitPerAbi: boolArg('split-per-abi'),
       targetArchs: stringsArg('target-platform').map<AndroidArch>(getAndroidArchForName),
+      multidexEnabled: boolArg('multidex'),
     );
     validateBuild(androidBuildInfo);
     displayNullSafetyMode(androidBuildInfo.buildInfo);
+    globals.terminal.usesTerminalUi = true;
     await androidBuilder.buildApk(
       project: FlutterProject.current(),
       target: targetFile,

packages/flutter_tools/lib/src/commands/build_appbundle.dart

@@ -39,6 +39,7 @@ class BuildAppBundleCommand extends BuildSubCommand {
     addEnableExperimentation(hide: !verboseHelp);
     usesAnalyzeSizeFlag();
     addAndroidSpecificBuildOptions(hide: !verboseHelp);
+    addMultidexOption();
     argParser.addMultiOption('target-platform',
       splitCommas: true,
       defaultsTo: <String>['android-arm', 'android-arm64', 'android-x64'],
@@ -110,6 +111,7 @@ class BuildAppBundleCommand extends BuildSubCommand {
 
     final AndroidBuildInfo androidBuildInfo = AndroidBuildInfo(await getBuildInfo(),
       targetArchs: stringsArg('target-platform').map<AndroidArch>(getAndroidArchForName),
+      multidexEnabled: boolArg('multidex'),
     );
     // Do all setup verification that doesn't involve loading units. Checks that
     // require generated loading units are done after gen_snapshot in assemble.
@@ -144,6 +146,7 @@ class BuildAppBundleCommand extends BuildSubCommand {
 
     validateBuild(androidBuildInfo);
     displayNullSafetyMode(androidBuildInfo.buildInfo);
+    globals.terminal.usesTerminalUi = true;
     await androidBuilder.buildAab(
       project: FlutterProject.current(),
       target: targetFile,

packages/flutter_tools/lib/src/commands/drive.dart

@@ -65,6 +65,7 @@ class DriveCommand extends RunCommandBase {
     // to prevent a local network permission dialog on iOS 14+,
     // which cannot be accepted or dismissed in a CI environment.
     addPublishPort(enabledByDefault: false, verboseHelp: verboseHelp);
+    addMultidexOption();
     argParser
       ..addFlag('keep-app-running',
         defaultsTo: null,
@@ -251,6 +252,8 @@ class DriveCommand extends RunCommandBase {
             'trace-startup': traceStartup,
           if (web)
             '--no-launch-chrome': true,
+          if (boolArg('multidex'))
+            'multidex': true,
         }
       );
     } else {

packages/flutter_tools/lib/src/commands/run.dart

@@ -249,6 +249,7 @@ class RunCommand extends RunCommandBase {
     // This will allow subsequent "flutter attach" commands to connect to the VM
     // without needing to know the port.
     addPublishPort(verboseHelp: verboseHelp);
+    addMultidexOption();
     argParser
       ..addFlag('enable-software-rendering',
         negatable: false,
@@ -500,6 +501,7 @@ class RunCommand extends RunCommandBase {
         dillOutputPath: stringArg('output-dill'),
         stayResident: stayResident,
         ipv6: ipv6,
+        multidexEnabled: boolArg('multidex'),
       );
     } else if (webMode) {
       return webRunnerFactory.createWebRunner(

packages/flutter_tools/lib/src/resident_runner.dart

@@ -416,7 +416,9 @@ class FlutterDevice {
     }
     devFSWriter = device.createDevFSWriter(package, userIdentifier);
 
-    final Map<String, dynamic> platformArgs = <String, dynamic>{};
+    final Map<String, dynamic> platformArgs = <String, dynamic>{
+      'multidex': hotRunner.multidexEnabled,
+    };
 
     await startEchoingDeviceLog();
 

packages/flutter_tools/lib/src/run_hot.dart

@@ -93,6 +93,7 @@ class HotRunner extends ResidentRunner {
     bool stayResident = true,
     bool ipv6 = false,
     bool machine = false,
+    this.multidexEnabled = false,
     ResidentDevtoolsHandlerFactory devtoolsHandler = createDefaultHandler,
     StopwatchFactory stopwatchFactory = const StopwatchFactory(),
     ReloadSourcesHelper reloadSourcesHelper = _defaultReloadSourcesHelper,
@@ -120,6 +121,7 @@ class HotRunner extends ResidentRunner {
   final bool benchmarkMode;
   final File applicationBinary;
   final bool hostIsIde;
+  final bool multidexEnabled;
 
   /// When performing a hot restart, the tool needs to upload a new main.dart.dill to
   /// each attached device's devfs. Replacing the existing file is not safe and does

packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -818,6 +818,16 @@ abstract class FlutterCommand extends Command<void> {
     );
   }
 
+  void addMultidexOption({ bool hide = false }) {
+    argParser.addFlag('multidex',
+      negatable: true,
+      defaultsTo: true,
+      help: 'When enabled, indicates that the app should be built with multidex support. This '
+            'flag adds the dependencies for multidex when the minimum android sdk is 20 or '
+            'below. For android sdk versions 21 and above, multidex support is native.',
+    );
+  }
+
   /// Adds build options common to all of the desktop build commands.
   void addCommonDesktopBuildOptions({ @required bool verboseHelp }) {
     addBuildModeFlags(verboseHelp: verboseHelp);

packages/flutter_tools/templates/app_shared/android.tmpl/app/src/main/AndroidManifest.xml.tmpl

@@ -2,6 +2,7 @@
     package="{{androidIdentifier}}">
    <application
         android:label="{{projectName}}"
+        android:name="${applicationName}"
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"

packages/flutter_tools/test/commands.shard/permeable/build_apk_test.dart

@@ -157,6 +157,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
@@ -186,6 +187,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Psplit-debug-info=${tempDir.path}',
           '-Ptrack-widget-creation=true',
@@ -216,6 +218,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Pextra-front-end-options=foo,bar',
           '-Ptrack-widget-creation=true',
@@ -246,6 +249,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
@@ -281,6 +285,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
@@ -335,6 +340,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',
@@ -381,6 +387,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=${globals.fs.path.join(tempDir.path, 'flutter_project', 'lib', 'main.dart')}',
+          '-Pbase-application-name=android.app.Application',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=true',
           '-Ptree-shake-icons=true',

packages/flutter_tools/test/general.shard/android/android_gradle_builder_test.dart

@@ -56,6 +56,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -101,6 +102,7 @@ void main() {
                 String line,
                 FlutterProject project,
                 bool usesAndroidX,
+                bool multidexEnabled
               }) async {
                 handlerCalled = true;
                 return GradleBuildStatus.exit;
@@ -142,6 +144,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -156,6 +159,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -205,6 +209,7 @@ void main() {
                 String line,
                 FlutterProject project,
                 bool usesAndroidX,
+                bool multidexEnabled
               }) async {
                 return GradleBuildStatus.retry;
               },
@@ -243,6 +248,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -288,6 +294,7 @@ void main() {
                 String line,
                 FlutterProject project,
                 bool usesAndroidX,
+                bool multidexEnabled
               }) async {
                 handlerCalled = true;
                 return GradleBuildStatus.exit;
@@ -329,6 +336,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -388,6 +396,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -402,6 +411,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -450,6 +460,7 @@ void main() {
               String line,
               FlutterProject project,
               bool usesAndroidX,
+                bool multidexEnabled
             }) async {
               return GradleBuildStatus.retry;
             },
@@ -488,6 +499,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -580,6 +592,7 @@ void main() {
           '-q',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -765,6 +778,7 @@ void main() {
           '-Plocal-engine-out=out/android_arm',
           '-Ptarget-platform=android-arm',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -838,6 +852,7 @@ void main() {
           '-Plocal-engine-out=out/android_arm64',
           '-Ptarget-platform=android-arm64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -911,6 +926,7 @@ void main() {
           '-Plocal-engine-out=out/android_x86',
           '-Ptarget-platform=android-x86',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -984,6 +1000,7 @@ void main() {
           '-Plocal-engine-out=out/android_x64',
           '-Ptarget-platform=android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',
@@ -1056,6 +1073,7 @@ void main() {
           '--no-daemon',
           '-Ptarget-platform=android-arm,android-arm64,android-x64',
           '-Ptarget=lib/main.dart',
+          '-Pbase-application-name=io.flutter.app.FlutterApplication',
           '-Pdart-obfuscation=false',
           '-Ptrack-widget-creation=false',
           '-Ptree-shake-icons=false',

packages/flutter_tools/test/general.shard/android/multidex_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.8
+
+import 'package:file/file.dart';
+import 'package:file/memory.dart';
+import 'package:flutter_tools/src/android/multidex.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/globals_null_migrated.dart' as globals;
+
+import '../../src/common.dart';
+import '../../src/context.dart';
+
+void main() {
+  testUsingContext('ensureMultidexUtilsExists returns when exists', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File applicationFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childDirectory('java')
+      .childDirectory('io')
+      .childDirectory('flutter')
+      .childDirectory('app')
+      .childFile('FlutterMultiDexApplication.java');
+    applicationFile.createSync(recursive: true);
+    applicationFile.writeAsStringSync('hello', flush: true);
+    expect(applicationFile.readAsStringSync(), 'hello');
+
+    ensureMultiDexApplicationExists(directory);
+
+    // File should remain untouched
+    expect(applicationFile.readAsStringSync(), 'hello');
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('ensureMultiDexApplicationExists generates when does not exist', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File applicationFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childDirectory('java')
+      .childDirectory('io')
+      .childDirectory('flutter')
+      .childDirectory('app')
+      .childFile('FlutterMultiDexApplication.java');
+
+    ensureMultiDexApplicationExists(directory);
+
+    final String contents = applicationFile.readAsStringSync();
+    expect(contents.contains('FlutterMultiDexApplication'), true);
+    expect(contents.contains('MultiDex.install(this);'), true);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('multiDexApplicationExists false when does not exist', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    expect(multiDexApplicationExists(directory), false);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('multiDexApplicationExists true when does exist', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File utilsFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childDirectory('java')
+      .childDirectory('io')
+      .childDirectory('flutter')
+      .childDirectory('app')
+      .childFile('FlutterMultiDexApplication.java');
+    utilsFile.createSync(recursive: true);
+
+    expect(multiDexApplicationExists(directory), true);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('androidManifestHasNameVariable true with valid manifest', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File applicationFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childFile('AndroidManifest.xml');
+    applicationFile.createSync(recursive: true);
+    applicationFile.writeAsStringSync(r'''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.multidexapp">
+   <application
+        android:label="multidextest2"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher">
+    </application>
+</manifest>
+''', flush: true);
+    expect(androidManifestHasNameVariable(directory), true);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('androidManifestHasNameVariable false with no android:name attribute', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File applicationFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childFile('AndroidManifest.xml');
+    applicationFile.createSync(recursive: true);
+    applicationFile.writeAsStringSync(r'''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.multidexapp">
+   <application
+        android:label="multidextest2"
+        android:icon="@mipmap/ic_launcher">
+    </application>
+''', flush: true);
+    expect(androidManifestHasNameVariable(directory), false);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('androidManifestHasNameVariable false with incorrect android:name attribute', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File applicationFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childFile('AndroidManifest.xml');
+    applicationFile.createSync(recursive: true);
+    applicationFile.writeAsStringSync(r'''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.multidexapp">
+   <application
+        android:label="multidextest2"
+        android:name="io.flutter.app.FlutterApplication"
+        android:icon="@mipmap/ic_launcher">
+    </application>
+''', flush: true);
+    expect(androidManifestHasNameVariable(directory), false);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('androidManifestHasNameVariable false with invalid xml manifest', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    final File applicationFile = directory.childDirectory('android')
+      .childDirectory('app')
+      .childDirectory('src')
+      .childDirectory('main')
+      .childFile('AndroidManifest.xml');
+    applicationFile.createSync(recursive: true);
+    applicationFile.writeAsStringSync(r'''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.multidexapp">
+   <application
+        android:label="multidextest2"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher">
+    </application>
+''', flush: true);
+    expect(androidManifestHasNameVariable(directory), false);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+
+  testUsingContext('androidManifestHasNameVariable false with no manifest file', () async {
+    final Directory directory = globals.fs.currentDirectory;
+    expect(androidManifestHasNameVariable(directory), false);
+  }, overrides: <Type, Generator>{
+    FileSystem: () => MemoryFileSystem.test(),
+    ProcessManager: () => FakeProcessManager.any(),
+  });
+}

packages/flutter_tools/test/integration.shard/multidex_build_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.8
+
+import 'package:file/file.dart';
+import 'package:flutter_tools/src/base/io.dart';
+
+import '../src/common.dart';
+import 'test_data/multidex_project.dart';
+import 'test_driver.dart';
+import 'test_utils.dart';
+
+void main() {
+  Directory tempDir;
+  FlutterRunTestDriver _flutter;
+
+  setUp(() async {
+    tempDir = createResolvedTempDirectorySync('run_test.');
+    _flutter = FlutterRunTestDriver(tempDir);
+  });
+
+  tearDown(() async {
+    await _flutter.stop();
+    tryToDelete(tempDir);
+  });
+
+  testWithoutContext('simple build apk succeeds', () async {
+    final MultidexProject project = MultidexProject(true);
+    await project.setUpIn(tempDir);
+    final String flutterBin = fileSystem.path.join(getFlutterRoot(), 'bin', 'flutter');
+    final ProcessResult result = await processManager.run(<String>[
+      flutterBin,
+      ...getLocalEngineArguments(),
+      'build',
+      'apk',
+      '--debug',
+    ], workingDirectory: tempDir.path);
+
+    expect(result.exitCode, 0);
+    expect(result.stdout.toString(), contains('app-debug.apk'));
+  });
+
+  testWithoutContext('simple build apk without FlutterMultiDexApplication fails', () async {
+    final MultidexProject project = MultidexProject(false);
+    await project.setUpIn(tempDir);
+    final String flutterBin = fileSystem.path.join(getFlutterRoot(), 'bin', 'flutter');
+    final ProcessResult result = await processManager.run(<String>[
+      flutterBin,
+      ...getLocalEngineArguments(),
+      'build',
+      'apk',
+      '--debug',
+    ], workingDirectory: tempDir.path);
+
+    expect(result.stderr.toString(), contains('Cannot fit requested classes in a single dex file'));
+    expect(result.stderr.toString(), contains('The number of method references in a .dex file cannot exceed 64K.'));
+    expect(result.exitCode, 1);
+  });
+}