Flutter doctor should require java 1.8+ (1.7 throws exception)

[relaerian]

Steps to Reproduce

1. Upgrade Flutter
2. cd to gallery app
3. run flutter run
4. experience crash

Flutter Doctor

[✓] Flutter (on Mac OS, channel alpha)
    • Flutter at /Users/redacted/documents/flutter
    • Framework revision 8128c56f8f (2 days ago), 2016-09-12 16:46:52
    • Engine revision 12fc138524
    • Tools Dart version 1.20.0-dev.1.0

[✓] Android toolchain - develop for Android devices (Android SDK 24.0.2)
    • Android SDK at /Users/redacted/Library/Android/sdk
    • Platform android-24, build-tools 24.0.2
    • Java(TM) SE Runtime Environment (build 1.7.0_79-b15)

[-] iOS toolchain - develop for iOS devices
    x XCode not installed; this is necessary for iOS development.
      Download at https://developer.apple.com/xcode/download/.
    x ideviceinstaller not available; this is used to discover connected iOS devices.
      Install via 'brew install ideviceinstaller'.
    x ios-deploy not available; this is used to deploy to connected iOS devices.
      Install via 'brew install ios-deploy'.

[✓] Atom - a lightweight development environment for Flutter
    • flutter plugin version 0.2.4
    • dartlang plugin version 0.6.38

[✓] Connected devices
    • Nexus 5 • 076a67630187ee88 • android-arm

Logs and Crash Reports

Building APK in debug mode (android-arm)...              
Exception in thread "main" java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
Exception from flutter run: Exit code 1 from: /Users/redacted/Library/Android/sdk/build-tools/24.0.2/dx --dex --force-jumbo --output /var/folders/zk/ndxbmbvx0rj154l5djbtff9r0000gn/T/flutter_toolsXd008n/classes.dex /Users/redacted/documents/flutter/bin/cache/artifacts/engine/android-arm/classes.dex.jar
package:flutter_tools/src/base/process.dart 196                   _runWithLoggingSync
package:flutter_tools/src/base/process.dart 135                   runCheckedSync
package:flutter_tools/src/commands/build_apk.dart 107             _ApkBuilder.compileClassesDex
package:flutter_tools/src/commands/build_apk.dart 355             _buildApk
package:flutter_tools/src/commands/build_apk.dart 582             buildAndroid.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/flx.dart 66                             buildFlx.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/flx.dart 156                            assemble.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/asset.dart 144                          AssetBundle.build.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/asset.dart 290                          _obtainLicenses.<async>
===== asynchronous gap ===========================
dart:async                                                        _Completer.completeError
package:flutter_tools/src/commands/build_apk.dart 599             buildAndroid.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/flx.dart 66                             buildFlx.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/flx.dart 156                            assemble.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/asset.dart 144                          AssetBundle.build.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/asset.dart 290                          _obtainLicenses.<async>
===== asynchronous gap ===========================
dart:async                                                        _asyncThenWrapperHelper
package:flutter_tools/src/commands/build_apk.dart                 buildAndroid
package:flutter_tools/src/commands/build_apk.dart 639             buildApk.<async>
===== asynchronous gap ===========================
dart:async                                                        Future.Future.microtask
package:flutter_tools/src/commands/build_apk.dart                 buildApk
package:flutter_tools/src/run.dart 127                            RunAndStayResident._run.<async>
===== asynchronous gap ===========================
dart:async                                                        Future.Future.microtask
package:flutter_tools/src/run.dart                                RunAndStayResident._run
package:flutter_tools/src/run.dart 48                             RunAndStayResident.run.<fn>
dart:async                                                        runZoned
package:flutter_tools/src/run.dart 47                             RunAndStayResident.run
package:flutter_tools/src/commands/run.dart 185                   RunCommand.runInProject.<async>
===== asynchronous gap ===========================
dart:async                                                        Future.Future.microtask
package:flutter_tools/src/commands/run.dart                       RunCommand.runInProject
package:flutter_tools/src/runner/flutter_command.dart 192         FlutterCommand._run.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/dart/pub.dart 60                        pubGet.<async>
===== asynchronous gap ===========================
dart:async                                                        _asyncThenWrapperHelper
package:flutter_tools/src/runner/flutter_command.dart             FlutterCommand._run
package:flutter_tools/src/runner/flutter_command.dart 116         FlutterCommand.run
package:args/command_runner.dart 177                              CommandRunner.runCommand.<fn>
dart:async                                                        Future.Future.sync
package:args/command_runner.dart 130                              CommandRunner.runCommand
package:flutter_tools/src/runner/flutter_command_runner.dart 177  FlutterCommandRunner.runCommand.<async>
dart:async                                                        _SyncCompleter.complete
package:flutter_tools/src/cache.dart 71                           Cache.lock.<async>
===== asynchronous gap ===========================
dart:async                                                        _asyncThenWrapperHelper
package:flutter_tools/src/runner/flutter_command_runner.dart      FlutterCommandRunner.runCommand
package:args/command_runner.dart 104                              CommandRunner.run.<fn>
dart:async                                                        Future.Future.sync
package:args/command_runner.dart 104                              CommandRunner.run
package:flutter_tools/src/runner/flutter_command_runner.dart 123  FlutterCommandRunner.run
package:flutter_tools/executable.dart 94                          main.<async>.<fn>.<async>
===== asynchronous gap ===========================
package:stack_trace                                               Chain.capture
package:flutter_tools/executable.dart 88                          main.<async>

For more information about diagnosing and reporting Flutter bugs, please see https://flutter.io/bug-reports/.

@apwilson

[apwilson]

I got @TenzinJenkins to install an updated version of java (1.8). The crash went away. Maybe this issue should be that flutter doctor doesn't indicate that 1.7 is "bad 'mkay?"

[eseidelGoogle]

We pull the version, but don't check that it's 1.8+, easy fix:
https://github.com/flutter/flutter/blob/master/packages/flutter_tools/lib/src/android/android_workflow.dart#L85