Unsupported major.minor version when doing GWT compile in eclipse

Question

So I'm getting the following exception: I know that major.minor version exceptions come when you are compiling with an old jdk and running with a newer one but i'm just doing GWT compile. Can anyone shed some light on this:

Compiling module com.domkee.entities.Entities
[ERROR] Unexpected internal compiler error
java.lang.UnsupportedClassVersionError: com/domkee/entities/client/annontations/Table : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:247)
    at com.google.gwt.dev.javac.TypeOracleMediator.getAnnotationClass(TypeOracleMediator.java:575)
    at com.google.gwt.dev.javac.TypeOracleMediator.resolveAnnotation(TypeOracleMediator.java:643)
    at com.google.gwt.dev.javac.TypeOracleMediator.resolveAnnotations(TypeOracleMediator.java:663)
    at com.google.gwt.dev.javac.TypeOracleMediator.resolveClass(TypeOracleMediator.java:809)
    at com.google.gwt.dev.javac.TypeOracleMediator.addNewTypes(TypeOracleMediator.java:439)
    at com.google.gwt.dev.javac.TypeOracleMediatorFromSource.addNewUnits(TypeOracleMediatorFromSource.java:52)
    at com.google.gwt.dev.javac.CompilationState.assimilateUnits(CompilationState.java:164)
    at com.google.gwt.dev.javac.CompilationState.<init>(CompilationState.java:82)
    at com.google.gwt.dev.javac.CompilationStateBuilder.doBuildFrom(CompilationStateBuilder.java:450)
    at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:370)
    at com.google.gwt.dev.cfg.ModuleDef.getCompilationState(ModuleDef.java:360)
    at com.google.gwt.dev.Precompile.precompile(Precompile.java:252)
    at com.google.gwt.dev.Precompile.precompile(Precompile.java:233)
    at com.google.gwt.dev.Precompile.precompile(Precompile.java:145)
    at com.google.gwt.dev.Compiler.run(Compiler.java:232)
    at com.google.gwt.dev.Compiler.run(Compiler.java:198)
    at com.google.gwt.dev.Compiler$1.run(Compiler.java:170)
    at com.google.gwt.dev.CompileTaskRunner.doRun(CompileTaskRunner.java:88)
    at com.google.gwt.dev.CompileTaskRunner.runWithAppropriateLogger(CompileTaskRunner.java:82)
    at com.google.gwt.dev.Compiler.main(Compiler.java:177)

Answer 1

I didn't figure the problem, but I figured the solution:

1. Close eclipse
2. I uninstalled all the jdks (Apparently I had like 4)
3. I installed a new one (java 1.6)
4. Run eclipse
5. set the compiler in window->preferences->java->compiler
6. Projects can have an individually set compilers that is not the default workspace compiler so go through each project and right->click ->preferences -> java compiler and set a 1.6 compiler.

Answer 2

I'm not familiar with these exceptions but make sure you setup the Java compiler to target Java 1.6 (and specifically not 1.7), and that you use Java 1.6 or newer to run the GWT compiler.