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What to do when Gradle raises unexpected NoClassDefFoundException

I have just lost an hour thanks to some obscure bug in Gradle caching mechanism.

If all of the sudden, Gradle raises Frankenstein errors at you like

$ gradle clean build

:buildSrc:compileJava UP-TO-DATE

:buildSrc:compileGroovy

Note: /Users/manu/projects/notbackedup/git/core/buildSrc/src/main/groovy/org/hibernate/gradle/testing/database/DatabaseMatrixPlugin.java uses unchecked or unsafe operations.

Note: Recompile with -Xlint:unchecked for details.

>>> a serious error occurred: hudson/util/DBAllocation

>>> stacktrace:

java.lang.NoClassDefFoundError: hudson/util/DBAllocation

at java.lang.Class.getDeclaredMethods0(Native Method)

at java.lang.Class.privateGetDeclaredMethods(Class.java:2427)

at java.lang.Class.getDeclaredMethods(Class.java:1791)

at org.codehaus.groovy.vmplugin.v5.Java5.configureClassNode(Java5.java:318)

at org.codehaus.groovy.ast.ClassNode.lazyClassInit(ClassNode.java:263)

at org.codehaus.groovy.ast.ClassNode.getInterfaces(ClassNode.java:341)

at org.codehaus.groovy.ast.ClassNode.declaresInterface(ClassNode.java:929)

at org.codehaus.groovy.ast.ClassNode.implementsInterface(ClassNode.java:909)

at org.codehaus.groovy.ast.ClassNode.isDerivedFromGroovyObject(ClassNode.java:899)

at org.codehaus.groovy.classgen.AsmClassGenerator.isGroovyObject(AsmClassGenerator.java:2752)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitPropertyExpression(AsmClassGenerator.java:2728)

at org.codehaus.groovy.ast.expr.PropertyExpression.visit(PropertyExpression.java:55)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitAndAutoboxBoolean(AsmClassGenerator.java:4122)

at org.codehaus.groovy.classgen.AsmClassGenerator.makeCallSite(AsmClassGenerator.java:2182)

at org.codehaus.groovy.classgen.AsmClassGenerator.makeCall(AsmClassGenerator.java:2019)

at org.codehaus.groovy.classgen.AsmClassGenerator.makeCall(AsmClassGenerator.java:2005)

at org.codehaus.groovy.classgen.AsmClassGenerator.makeInvokeMethodCall(AsmClassGenerator.java:1990)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitMethodCallExpression(AsmClassGenerator.java:2342)

at org.codehaus.groovy.ast.expr.MethodCallExpression.visit(MethodCallExpression.java:75)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitBooleanExpression(AsmClassGenerator.java:1959)

at org.codehaus.groovy.ast.expr.BooleanExpression.visit(BooleanExpression.java:40)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitIfElse(AsmClassGenerator.java:913)

at org.codehaus.groovy.ast.stmt.IfStatement.visit(IfStatement.java:41)

at org.codehaus.groovy.ast.CodeVisitorSupport.visitBlockStatement(CodeVisitorSupport.java:35)

at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitBlockStatement(ClassCodeVisitorSupport.java:165)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitBlockStatement(AsmClassGenerator.java:738)

at org.codehaus.groovy.ast.stmt.BlockStatement.visit(BlockStatement.java:69)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitIfElse(AsmClassGenerator.java:921)

at org.codehaus.groovy.ast.stmt.IfStatement.visit(IfStatement.java:41)

at org.codehaus.groovy.ast.CodeVisitorSupport.visitBlockStatement(CodeVisitorSupport.java:35)

at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitBlockStatement(ClassCodeVisitorSupport.java:165)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitBlockStatement(AsmClassGenerator.java:738)

at org.codehaus.groovy.ast.stmt.BlockStatement.visit(BlockStatement.java:69)

at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitClassCodeContainer(ClassCodeVisitorSupport.java:101)

at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitConstructorOrMethod(ClassCodeVisitorSupport.java:112)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitStdMethod(AsmClassGenerator.java:626)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitConstructorOrMethod(AsmClassGenerator.java:601)

at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitMethod(ClassCodeVisitorSupport.java:123)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitMethod(AsmClassGenerator.java:696)

at org.codehaus.groovy.ast.ClassNode.visitContents(ClassNode.java:1039)

at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitClass(ClassCodeVisitorSupport.java:50)

at org.codehaus.groovy.classgen.AsmClassGenerator.visitClass(AsmClassGenerator.java:276)

at org.codehaus.groovy.control.CompilationUnit$12.call(CompilationUnit.java:748)

at org.codehaus.groovy.control.CompilationUnit.applyToPrimaryClassNodes(CompilationUnit.java:942)

at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:519)

at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:497)

at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:474)

at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:453)

at org.codehaus.groovy.tools.FileSystemCompiler.compile(FileSystemCompiler.java:67)

at org.codehaus.groovy.tools.FileSystemCompiler.doCompilation(FileSystemCompiler.java:180)

at org.codehaus.groovy.tools.FileSystemCompiler.commandLineCompile(FileSystemCompiler.java:148)

at org.codehaus.groovy.tools.FileSystemCompiler.main(FileSystemCompiler.java:162)

Caused by: java.lang.ClassNotFoundException: hudson.util.DBAllocation

at java.net.URLClassLoader$1.run(URLClassLoader.java:202)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:190)

at java.lang.ClassLoader.loadClass(ClassLoader.java:306)

at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:696)

at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:793)

at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

... 52 more

FAILURE: Build failed with an exception.

* What went wrong:

Execution failed for task ':compileGroovy'.

Cause: Forked groovyc returned error code: 1

* Try:

Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Simply nuke the Gradle cache from your project. I don't know if they are supposed to be in a standard location but for Hibernate the following commands did the trick

rm -fR .gradle

rm -fR buildSrc/.gradle

I wonder what will happen first, tools just working or world peace :)

Groovy Annotations

I have been hammering (nicely) Guillaume for a long time now to get Annotations support in Groovy.
Thanks to Alexandru Popescu, this is now an official work in progress, and one that progress well :-)
I am thrilled by the possibilities to combine JavaEE (or any modern annotation based framework) and Groovy. If you wondered about the dynamic language you wanted to use, don't anymore.

Like the Hibernate team when we worked on the Java Persistence certification, the Groovy team must have been very frustrated to focus on Groovy 1.0 and not being able to innovate as fast as they did. They are now back on track.

Give a try to Groovy SVN trunk and enjoy.

To copy a file in ...

... Java

private static void copyFile(File srcFile, File destFile) 
       throws IOException {
   FileInputStream is = null;
   FileOutputStream os = null;
   try {
       is = new FileInputStream(srcFile);
       FileChannel iChannel = is.getChannel();
       os = new FileOutputStream( destFile, false );
       FileChannel oChannel = os.getChannel();
       oChannel.transferFrom( iChannel, 0, srcFile.length() );
   }
   finally {
       if (is != null) is.close();
       if (os != null) os.close();
   }
}

static void copyFile(File source, File destination) {
   def reader = source.newReader()
   destination.withWriter { writer ->
       writer << reader
   }
   reader.close()
}

static void copyFile(File source, File destination) {
   new AntBuilder().copy(file:'$source.canonicalPath', 
                         tofile:'$destination.canonicalPath')
}

cp source destination