Why isn't Drools working with Java 8? - maven

Question

I just installed the final version of Java 8. When I try to build my project with Maven, many tests fail if I use Java 8, but pass fine with Java 7. I've tried running it via the command line with JAVA_HOME set to C:\Program Files\Java\jdk1.8.0 and via Eclipse with jdk1.8.0 selected as the default JRE in Installed JREs. Both fail. Note that the tests that fail all use Drools 6 (and its dependencies).
Here is the output:
-------------------------------------------------------------------------------
Test set: com.local.lds.rules.LocmChiTest
-------------------------------------------------------------------------------
Tests run: 3, Failures: 0, Errors: 3, Skipped: 0, Time elapsed: 1.245 sec <<< FAILURE!
test(com.local.lds.rules.LocmChiTest) Time elapsed: 0.001 sec <<< ERROR!
java.lang.ExceptionInInitializerError
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:187)
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:63)
at mockit.Invocation.proceed(Invocation.java:192)
at mockit.integration.junit4.internal.BlockJUnit4ClassRunnerDecorator.createTest(BlockJUnit4ClassRunnerDecorator.java:59)
at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at mockit.internal.util.MethodReflection.invokeWithCheckedThrows(MethodReflection.java:95)
at mockit.internal.mockups.MockMethodBridge.callMock(MockMethodBridge.java:75)
at mockit.internal.mockups.MockMethodBridge.invoke(MockMethodBridge.java:41)
at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java)
at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:236)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:233)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:53)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:123)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:104)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:164)
at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:110)
at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:175)
at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcessWhenForked(SurefireStarter.java:107)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:68)
Caused by: java.lang.RuntimeException: wrong class format
at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.findType(EclipseJavaCompiler.java:279)
at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.findType(EclipseJavaCompiler.java:219)
at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.askForType(LookupEnvironment.java:113)
at org.eclipse.jdt.internal.compiler.lookup.UnresolvedReferenceBinding.resolve(UnresolvedReferenceBinding.java:49)
at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveType(BinaryTypeBinding.java:122)
at org.eclipse.jdt.internal.compiler.lookup.ParameterizedTypeBinding.resolve(ParameterizedTypeBinding.java:861)
at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveType(BinaryTypeBinding.java:100)
at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.resolveTypeFor(BinaryTypeBinding.java:1081)
at org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.getField(BinaryTypeBinding.java:869)
at org.eclipse.jdt.internal.compiler.lookup.Scope.findField(Scope.java:1052)
at org.eclipse.jdt.internal.compiler.lookup.Scope.findField(Scope.java:998)
at org.eclipse.jdt.internal.compiler.lookup.MethodScope.findField(MethodScope.java:354)
at org.eclipse.jdt.internal.compiler.lookup.BlockScope.getBinding(BlockScope.java:474)
at org.eclipse.jdt.internal.compiler.ast.QualifiedNameReference.resolveType(QualifiedNameReference.java:930)
at org.eclipse.jdt.internal.compiler.ast.MessageSend.resolveType(MessageSend.java:374)
at org.eclipse.jdt.internal.compiler.ast.Expression.resolve(Expression.java:947)
at org.eclipse.jdt.internal.compiler.ast.Block.resolve(Block.java:90)
at org.eclipse.jdt.internal.compiler.ast.IfStatement.resolve(IfStatement.java:260)
at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolveStatements(AbstractMethodDeclaration.java:456)
at org.eclipse.jdt.internal.compiler.ast.MethodDeclaration.resolveStatements(MethodDeclaration.java:252)
at org.eclipse.jdt.internal.compiler.ast.AbstractMethodDeclaration.resolve(AbstractMethodDeclaration.java:415)
at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.resolve(TypeDeclaration.java:1148)
at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.resolve(TypeDeclaration.java:1258)
at org.eclipse.jdt.internal.compiler.ast.CompilationUnitDeclaration.resolve(CompilationUnitDeclaration.java:539)
at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:763)
at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:468)
at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler.compile(EclipseJavaCompiler.java:405)
at org.drools.compiler.commons.jci.compilers.AbstractJavaCompiler.compile(AbstractJavaCompiler.java:49)
at org.drools.compiler.rule.builder.dialect.java.JavaDialect.compileAll(JavaDialect.java:405)
at org.drools.compiler.compiler.DialectCompiletimeRegistry.compileAll(DialectCompiletimeRegistry.java:46)
at org.drools.compiler.compiler.PackageRegistry.compileAll(PackageRegistry.java:110)
at org.drools.compiler.compiler.PackageBuilder.compileAll(PackageBuilder.java:1334)
at org.drools.compiler.compiler.PackageBuilder.compileAllRules(PackageBuilder.java:975)
at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.buildRules(CompositeKnowledgeBuilderImpl.java:266)
at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.buildPackages(CompositeKnowledgeBuilderImpl.java:98)
at org.drools.compiler.compiler.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:87)
at org.drools.compiler.kie.builder.impl.AbstractKieModule.buildKnowledgePackages(AbstractKieModule.java:204)
at org.drools.compiler.kie.builder.impl.AbstractKieProject.verify(AbstractKieProject.java:39)
at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildKieProject(KieBuilderImpl.java:323)
at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:193)
at com.local.lds.rules.RuleEngineManager.buildKieBase(RuleEngineManager.java:90)
at com.local.lds.rules.LocmChiTest.<clinit>(LocmChiTest.java:33)
... 41 more
Caused by: org.eclipse.jdt.internal.compiler.classfmt.ClassFormatException
at org.eclipse.jdt.internal.compiler.classfmt.ClassFileReader.<init>(ClassFileReader.java:372)
at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.createNameEnvironmentAnswer(EclipseJavaCompiler.java:303)
at org.drools.compiler.commons.jci.compilers.EclipseJavaCompiler$2.findType(EclipseJavaCompiler.java:274)
... 82 more
testNoFeatured(com.local.lds.rules.LocmChiTest) Time elapsed: 0 sec <<< ERROR!
java.lang.NoClassDefFoundError: Could not initialize class com.local.lds.rules.LocmChiTest
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:187)
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:63)
at mockit.Invocation.proceed(Invocation.java:192)
at mockit.integration.junit4.internal.BlockJUnit4ClassRunnerDecorator.createTest(BlockJUnit4ClassRunnerDecorator.java:59)
at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at mockit.internal.util.MethodReflection.invokeWithCheckedThrows(MethodReflection.java:95)
at mockit.internal.mockups.MockMethodBridge.callMock(MockMethodBridge.java:75)
at mockit.internal.mockups.MockMethodBridge.invoke(MockMethodBridge.java:41)
at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java)
at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:236)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:233)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:53)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:123)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:104)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:164)
at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:110)
at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:175)
at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcessWhenForked(SurefireStarter.java:107)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:68)
testFeaturedSort(com.local.lds.rules.LocmChiTest) Time elapsed: 0.001 sec <<< ERROR!
java.lang.NoClassDefFoundError: Could not initialize class com.local.lds.rules.LocmChiTest
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:408)
at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:187)
at sun.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at mockit.internal.util.MethodReflection.invoke(MethodReflection.java:63)
at mockit.Invocation.proceed(Invocation.java:192)
at mockit.integration.junit4.internal.BlockJUnit4ClassRunnerDecorator.createTest(BlockJUnit4ClassRunnerDecorator.java:59)
at sun.reflect.GeneratedMethodAccessor7.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at mockit.internal.util.MethodReflection.invokeWithCheckedThrows(MethodReflection.java:95)
at mockit.internal.mockups.MockMethodBridge.callMock(MockMethodBridge.java:75)
at mockit.internal.mockups.MockMethodBridge.invoke(MockMethodBridge.java:41)
at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java)
at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:236)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:233)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:53)
at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:123)
at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:104)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:483)
at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:164)
at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:110)
at org.apache.maven.surefire.booter.SurefireStarter.invokeProvider(SurefireStarter.java:175)
at org.apache.maven.surefire.booter.SurefireStarter.runSuitesInProcessWhenForked(SurefireStarter.java:107)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:68)
So is this a problem with Java 8, Maven, the Surefire plugin, or Drools?

Answer 1

Looks like a bug in Drools (in the Eclipse compiler which is the default):
Bugzilla
JIRA (thanks Laune)
They're looking into fixing it in 6.1.0.Beta2.
Meanwhile, try this workaround:
Override the ecj dependency to version 4.3.1.

Answer 2

I have solved this issue by edit pom in maven.
<dependency>
<groupId>org.eclipse.jdt.core.compiler</groupId>
<artifactId>ecj</artifactId>
<version>4.5.1</version>
</dependency>
<!-- core -->
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-core</artifactId>
<version>5.5.0.Final</version>
</dependency>
<dependency>
<groupId>org.drools</groupId>
<artifactId>drools-compiler</artifactId>
<version>5.5.0.Final</version>
<exclusions>
<exclusion>
<groupId>org.eclipse.jdt.core.compiler</groupId>
<artifactId>ecj</artifactId>
</exclusion>
</exclusions>
</dependency>

Answer 3

Update org.eclipse.jdt.core.jar to latest available one .
In our case we have updated org.eclipse.jdt.core-3.5.1.v_972_R35x.jar to org.eclipse.jdt.core_3.11.2.v20160128-0629.jar .
This is the jar which decides the java_version with which the drools code will get compiled.
once ur old java-6 compatible drools code getting compiled in java -8 . u can run it using java -8 without any such error .
These are proven steps .
Please revert back if any doubt .

Answer 4

Update your org.eclipse.jdt.internal.compiler(ecj.jar) to latest i.e, use ecj-4.4.jar and try.

Answer 5

ECJ, which is used to compile java code in your rules, only began supporting Java 8 syntax recently with Luna (4.4) so an update is required.
If you are wanting to use Java 8 syntax in your rules you will also want to use Drools 6.4.0.Final as they now recognizing Java 8 as Java 8 (they were mapping 8 over to 7 to fix issues with ECJ 4.3)
MVEL 2.2.X version or later, which is a shorthand alternative to Java syntax, also supports Java 8.