GWT Gin 2.1 Unsupported major.minor version 51.0

Question

I am getting an error when trying to compile gwt project that is typically caused by a jre 1.7 (51.0) compiled class. I have verified that my classes are getting compiled with 1.6 version. I am almost positive that this is some other class that is getting included on the classpath but I am unable to get the gwt compiler to break when debugging a maven build. I am using eclipse to attempt to break debug maven build and adding breakpoints for the UnsupportClassVersionError and the UnableToCompleteException but the jvm is not stopping when this occurrs. I am GUESSING that maybe the GWT compiler is running under a separate process and I won't be able to easily catch those exceptions. Any pointers would be greatly appreciated. I would rather find a way to break on gwt exceptions but if someone knows why GIN is complaining about invalid class revisions that would be great too.

Here is the error when I am attempting to compile from command line using maven.

[INFO] --- gwt-maven-plugin:2.5.1:compile (default) @ smartbar ---
[INFO] Loading inherited module 'com.smartbar.SmartBar'
[INFO]    Loading inherited module 'com.smartbar.SmartBarCommon'
[INFO]       Loading inherited module 'com.google.gwt.inject.Inject'
[INFO]          [ERROR] Unexpected error while processing XML
[INFO] java.lang.UnsupportedClassVersionError: com/google/gwt/inject/rebind/GinjectorGenerator : Unsupported major.minor version 51.0
[INFO]  at java.lang.ClassLoader.defineClass1(Native Method)
[INFO]  at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
[INFO]  at java.lang.ClassLoader.defineClass(ClassLoader.java:615)


chinshaw$ java -version
java version "1.6.0_51"
Java(TM) SE Runtime Environment (build 1.6.0_51-b11-457-11M4509)
Java HotSpot(TM) 64-Bit Server VM (build 20.51-b01-457, mixed mode)


chinshaw$ find . -name '*.class' | xargs file | head -10
    ./WEB-INF/classes/com/testing/client/activity/AbstractActivity.class:                                compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/activity/EstablishmentInventoryActivity.class:                  compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/activity/EstablishmentNavigationActivity.class:                 compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/ClientUserSession.class:                                        compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/events/EntityEditEvent$Handler.class:                           compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/events/EntityEditEvent.class:                                   compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/events/InventoryItemSelectionEvent$Handler.class:               compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client/events/InventoryItemSelectionEvent.class:                       compiled Java class data, version 50.0 (Java 1.6)
    ./WEB-INF/classes/com/testing/client

Temporary Solution

This may be just a problem with the maven repository but it appears that the 2.1.0 gin package is built with 1.7.0. I downgraded my dependencies to 2.0.0 and it works fine now.

desktop-mini:2.1.0 chinshaw$ pwd
/Users/chinshaw/.m2/repository/com/google/gwt/inject/gin/2.1.0
desktop-mini:inject chinshaw$ find . -name '*.class'  -exec file {} \; | head -10
./client/AbstractGinModule.class: compiled Java class data, version 51.0
./client/assistedinject/BindingCollector.class: compiled Java class data, version 51.0
./client/assistedinject/FactoryModule.class: compiled Java class data, version 51.0
./client/assistedinject/GinFactoryModuleBuilder.class: compiled Java class data, version 51.0
./client/AsyncProvider.class: compiled Java class data, version 51.0
./client/binder/GinAnnotatedBindingBuilder.class: compiled Java class data, version 51.0
./client/binder/GinAnnotatedConstantBindingBuilder.class: compiled Java class data, version 51.0
./client/binder/GinAnnotatedElementBuilder.class: compiled Java class data, version 51.0
./client/binder/GinBinder.class: compiled Java class data, version 51.0
./client/binder/GinConstantBindingBuilder.class: compiled Java class data, version 51.0

Here's the bug id, wish I had looked there first. Assumed it was a problem with another jar first though. http://code.google.com/p/google-gin/issues/detail?id=190

You can change the gin version to 2.1.1 The problem has been sorted out going forward. — Jon Lai Lam, Nov 04 '13 at 08:57

score 2 · Accepted Answer · answered Jul 13 '13 at 18:40

2

The enforceBytecodeVersion Enforcer Rule should be able to help you with these kind of issues. It'll go through all the dependencies to check if they match the required class version.

answered Jul 13 '13 at 18:40

Robert Scholte

11,889
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Thank you, thats a great little plugin. The surprising thing is that it was the gin dependency that is compiled with 1.7. WTF. Thanks again. – Chris Hinshaw Jul 13 '13 at 18:51

GWT Gin 2.1 Unsupported major.minor version 51.0

Temporary Solution

1 Answers1