Clean up null assumptions for Gradle classes (#83443)

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

@@ -190,7 +190,7 @@ class AndroidGradleBuilder implements AndroidBuilder {
     @required FlutterProject project,
     @required Set<AndroidBuildInfo> androidBuildInfo,
     @required String target,
-    @required String outputDirectoryPath,
+    String outputDirectoryPath,
     @required String buildNumber,
   }) async {
     Directory outputDirectory =
@@ -361,7 +361,8 @@ class AndroidGradleBuilder implements AndroidBuilder {
     if (target != null) {
       command.add('-Ptarget=$target');
     }
-    if (project.manifest.deferredComponents != null) {
+    final List<DeferredComponent> deferredComponents = project.manifest.deferredComponents;
+    if (deferredComponents != null) {
       if (deferredComponentsEnabled) {
         command.add('-Pdeferred-components=true');
         androidBuildInfo.buildInfo.dartDefines.add('validate-deferred-components=$validateDeferredComponents');
@@ -369,7 +370,7 @@ class AndroidGradleBuilder implements AndroidBuilder {
       // Pass in deferred components regardless of building split aot to satisfy
       // android dynamic features registry in build.gradle.
       final List<String> componentNames = <String>[];
-      for (final DeferredComponent component in project.manifest.deferredComponents) {
+      for (final DeferredComponent component in deferredComponents) {
         componentNames.add(component.name);
       }
       if (componentNames.isNotEmpty) {
@@ -756,7 +757,7 @@ class AndroidGradleBuilder implements AndroidBuilder {
   Future<void> buildPluginsAsAar(
     FlutterProject flutterProject,
     AndroidBuildInfo androidBuildInfo, {
-    Directory buildDirectory,
+    @required Directory buildDirectory,
   }) async {
     final File flutterPluginFile = flutterProject.flutterPluginsFile;
     if (!flutterPluginFile.existsSync()) {
@@ -806,14 +807,13 @@ class AndroidGradleBuilder implements AndroidBuilder {
 /// Prints how to consume the AAR from a host app.
 void printHowToConsumeAar({
   @required Set<String> buildModes,
-  @required String androidPackage,
+  String androidPackage = 'unknown',
   @required Directory repoDirectory,
   @required Logger logger,
   @required FileSystem fileSystem,
   String buildNumber,
 }) {
   assert(buildModes != null && buildModes.isNotEmpty);
-  assert(androidPackage != null);
   assert(repoDirectory != null);
   buildNumber ??= '1.0';
 
@@ -919,10 +919,11 @@ Iterable<String> findApkFilesModule(
     if (apkFile.existsSync()) {
       return <File>[apkFile];
     }
-    if (buildInfo.flavor != null) {
+    final String flavor = buildInfo.flavor;
+    if (flavor != null) {
       // Android Studio Gradle plugin v3 adds flavor to path.
       apkFile = apkDirectory
-        .childDirectory(buildInfo.flavor)
+        .childDirectory(flavor)
         .childDirectory(modeName)
         .childFile(apkFileName);
       if (apkFile.existsSync()) {

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

@@ -18,8 +18,8 @@ typedef GradleErrorTest = bool Function(String);
 /// A Gradle error handled by the tool.
 class GradleHandledError {
   const GradleHandledError({
-    this.test,
-    this.handler,
+    @required this.test,
+    @required this.handler,
     this.eventLabel,
   });
 
@@ -29,10 +29,10 @@ class GradleHandledError {
 
   /// The handler function.
   final Future<GradleBuildStatus> Function({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) handler;
 
   /// The [BuildEvent] label is named gradle-[eventLabel].
@@ -85,10 +85,10 @@ final GradleHandledError permissionDeniedErrorHandler = GradleHandledError(
     'Permission denied',
   ]),
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     globals.printStatus('${globals.logger.terminal.warningMark} Gradle does not have execution permission.', emphasis: true);
     globals.printStatus(
@@ -122,10 +122,10 @@ final GradleHandledError networkErrorHandler = GradleHandledError(
     'Gateway Time-out'
   ]),
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     globals.printError(
       '${globals.logger.terminal.warningMark} Gradle threw an error while downloading artifacts from the network. '
@@ -152,10 +152,10 @@ final GradleHandledError r8FailureHandler = GradleHandledError(
     'com.android.tools.r8',
   ]),
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) 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);
@@ -191,10 +191,10 @@ final GradleHandledError androidXFailureHandler = GradleHandledError(
            _androidXFailureRegex.hasMatch(line);
   },
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     final bool hasPlugins = project.flutterPluginsFile.existsSync();
     if (!hasPlugins) {
@@ -259,10 +259,10 @@ final GradleHandledError licenseNotAcceptedHandler = GradleHandledError(
     'You have not accepted the license agreements of the following SDK components',
   ]),
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     const String licenseNotAcceptedMatcher =
       r'You have not accepted the license agreements of the following SDK components:\s*\[(.+)\]';
@@ -293,10 +293,10 @@ final GradleHandledError flavorUndefinedHandler = GradleHandledError(
     return _undefinedTaskPattern.hasMatch(line);
   },
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     final RunResult tasksRunResult = await globals.processUtils.run(
       <String>[
@@ -366,10 +366,10 @@ final GradleHandledError minSdkVersion = GradleHandledError(
     return _minSdkVersionPattern.hasMatch(line);
   },
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     final File gradleFile = project.directory
         .childDirectory('android')
@@ -405,10 +405,10 @@ final GradleHandledError transformInputIssue = GradleHandledError(
     return line.contains('https://issuetracker.google.com/issues/158753935');
   },
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     final File gradleFile = project.directory
         .childDirectory('android')
@@ -438,10 +438,10 @@ final GradleHandledError lockFileDepMissing = GradleHandledError(
     return line.contains('which is not part of the dependency lock state');
   },
   handler: ({
-    String line,
-    FlutterProject project,
-    bool usesAndroidX,
-    bool shouldBuildPluginAsAar,
+    @required String line,
+    @required FlutterProject project,
+    @required bool usesAndroidX,
+    @required bool shouldBuildPluginAsAar,
   }) async {
     final File gradleFile = project.directory
         .childDirectory('android')

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

@@ -19,6 +19,7 @@ import '../cache.dart';
 import '../globals_null_migrated.dart' as globals;
 import '../project.dart';
 import '../reporting/reporting.dart';
+import 'android_sdk.dart';
 
 const String _defaultGradleVersion = '6.7';
 
@@ -133,8 +134,13 @@ bool _isWithinVersionRange(
   assert(min != null);
   assert(max != null);
   final Version parsedTargetVersion = Version.parse(targetVersion);
-  return parsedTargetVersion >= Version.parse(min) &&
-         parsedTargetVersion <= Version.parse(max);
+  final Version minVersion = Version.parse(min);
+  final Version maxVersion = Version.parse(max);
+  return minVersion != null &&
+      maxVersion != null &&
+      parsedTargetVersion != null &&
+      parsedTargetVersion >= minVersion &&
+      parsedTargetVersion <= maxVersion;
 }
 
 /// Returns the Gradle version that is required by the given Android Gradle plugin version
@@ -217,8 +223,9 @@ void updateLocalProperties({
     changed = true;
   }
 
-  if (globals.androidSdk != null) {
-    changeIfNecessary('sdk.dir', globals.fsUtils.escapePath(globals.androidSdk.directory.path));
+  final AndroidSdk androidSdk = globals.androidSdk;
+  if (androidSdk != null) {
+    changeIfNecessary('sdk.dir', globals.fsUtils.escapePath(androidSdk.directory.path));
   }
 
   changeIfNecessary('flutter.sdk', globals.fsUtils.escapePath(Cache.flutterRoot));
@@ -248,8 +255,9 @@ void updateLocalProperties({
 /// Writes the path to the Android SDK, if known.
 void writeLocalProperties(File properties) {
   final SettingsFile settings = SettingsFile();
-  if (globals.androidSdk != null) {
-    settings.values['sdk.dir'] = globals.fsUtils.escapePath(globals.androidSdk.directory.path);
+  final AndroidSdk androidSdk = globals.androidSdk;
+  if (androidSdk != null) {
+    settings.values['sdk.dir'] = globals.fsUtils.escapePath(androidSdk.directory.path);
   }
   settings.writeContents(properties);
 }