i123643 print java version gradle

packages/flutter_tools/gradle/flutter.gradle

@@ -678,6 +678,23 @@ class FlutterPlugin implements Plugin<Project> {
         project.dependencies.add(configuration, dependency, config)
     }
 
+    // Add a task that can be called on flutter projects that prints the java version used in gradle.
+    //
+    // Format of the output of this task can be used in debugging what version of java gradle is using.
+    // Not recomended for use in time sensitive commands like `flutter run` or `flutter build` as
+    // gradle is slower than we want. Particularly in light of https://github.com/flutter/flutter/issues/119196.
+    //
+    private static void addTaskForJavaVersion(Project project) {
+        // Warning: the name of this task is used by other code. Change with caution.
+        project.tasks.register('javaVersion') {
+            description 'Print the current java version used by gradle. '
+                'see: https://docs.gradle.org/current/javadoc/org/gradle/api/JavaVersion.html'
+            doLast {
+                println(JavaVersion.current())
+            }
+        }
+    }
+
     /**
      * Returns a Flutter build mode suitable for the specified Android buildType.
      *
@@ -850,6 +867,7 @@ class FlutterPlugin implements Plugin<Project> {
         if (project.hasProperty('validate-deferred-components')) {
             validateDeferredComponentsValue = project.property('validate-deferred-components').toBoolean()
         }
+        addTaskForJavaVersion(project)
         def targetPlatforms = getTargetPlatforms()
         def addFlutterDeps = { variant ->
             if (shouldSplitPerAbi()) {

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

@@ -72,9 +72,8 @@ class GradleUtils {
     final Directory androidDir = project.android.hostAppGradleRoot;
     injectGradleWrapperIfNeeded(androidDir);
 
-    final File gradle = androidDir.childFile(
-      _platform.isWindows ? 'gradlew.bat' : 'gradlew',
-    );
+    final File gradle = androidDir.childFile(getGradlewFileName(_platform));
+
     if (gradle.existsSync()) {
       _logger.printTrace('Using gradle from ${gradle.absolute.path}.');
       // If the Gradle executable doesn't have execute permission,
@@ -290,3 +289,12 @@ void exitWithNoSdkMessage() {
     'Try setting the ANDROID_SDK_ROOT environment variable.'
   );
 }
+
+// return gradlew file name based on the platform.
+String getGradlewFileName(Platform platform) {
+  if (platform.isWindows) {
+    return 'gradlew.bat';
+  } else {
+    return 'gradlew';
+  }
+}

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

@@ -186,5 +186,11 @@ void main() {
         androidDirectory.childFile('gradlew').path,
       );
     });
+    testWithoutContext('getGradleFileName for notWindows', () {
+      expect(getGradlewFileName(notWindowsPlatform), 'gradlew');
+    });
+    testWithoutContext('getGradleFileName for windows', () {
+      expect(getGradlewFileName(windowsPlatform), 'gradlew.bat');
+    });
   });
 }

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

@@ -0,0 +1,57 @@
+// 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:file/file.dart';
+import 'package:flutter_tools/src/android/gradle_utils.dart'
+    show getGradlewFileName;
+import 'package:flutter_tools/src/base/io.dart';
+
+import '../src/common.dart';
+import 'test_utils.dart';
+
+void main() {
+  late Directory tempDir;
+
+  setUp(() async {
+    tempDir = createResolvedTempDirectorySync('run_test.');
+  });
+
+  tearDown(() async {
+    tryToDelete(tempDir);
+  });
+
+  testWithoutContext(
+      'gradle task exists named javaVersion that prints jdk version', () async {
+    // Create a new flutter project.
+    final String flutterBin =
+        fileSystem.path.join(getFlutterRoot(), 'bin', 'flutter');
+    ProcessResult result = await processManager.run(<String>[
+      flutterBin,
+      'create',
+      tempDir.path,
+      '--project-name=testapp',
+    ], workingDirectory: tempDir.path);
+    expect(result.exitCode, 0);
+    // Ensure that gradle files exists from templates.
+    result = await processManager.run(<String>[
+      flutterBin,
+      'build',
+      'apk',
+      '--config-only',
+    ], workingDirectory: tempDir.path);
+    expect(result.exitCode, 0);
+
+    final Directory androidApp = tempDir.childDirectory('android');
+    result = await processManager.run(<String>[
+      './${getGradlewFileName(platform)}',
+      ...getLocalEngineArguments(),
+      '-q', // quiet output.
+      'javaVersion',
+    ], workingDirectory: androidApp.path);
+    // Verify that gradlew has a javaVersion task.
+    expect(result.exitCode, 0);
+    // Verify the format is a number on its own line.
+    expect(result.stdout.toString(), matches(RegExp(r'\d\n')));
+  });
+}