Why am I getting a ClassCastException when generating javadocs?

Question

I'm using ant to generate javadocs, but get this exception over and over - why?

I'm using JDK version 1.6.0_06.

[javadoc] java.lang.ClassCastException: com.sun.tools.javadoc.ClassDocImpl cannot be cast to com.sun.javadoc.AnnotationTypeDoc
  [javadoc]     at com.sun.tools.javadoc.AnnotationDescImpl.annotationType(AnnotationDescImpl.java:46)
  [javadoc]     at com.sun.tools.doclets.formats.html.HtmlDocletWriter.getAnnotations(HtmlDocletWriter.java:1739)
  [javadoc]     at com.sun.tools.doclets.formats.html.HtmlDocletWriter.writeAnnotationInfo(HtmlDocletWriter.java:1713)
  [javadoc]     at com.sun.tools.doclets.formats.html.HtmlDocletWriter.writeAnnotationInfo(HtmlDocletWriter.java:1702)
  [javadoc]     at com.sun.tools.doclets.formats.html.HtmlDocletWriter.writeAnnotationInfo(HtmlDocletWriter.java:1681)
  [javadoc]     at com.sun.tools.doclets.formats.html.FieldWriterImpl.writeSignature(FieldWriterImpl.java:130)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.FieldBuilder.buildSignature(FieldBuilder.java:184)
  [javadoc]     at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
  [javadoc]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  [javadoc]     at java.lang.reflect.Method.invoke(Method.java:597)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.FieldBuilder.invokeMethod(FieldBuilder.java:114)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:90)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.AbstractMemberBuilder.build(AbstractMemberBuilder.java:56)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.FieldBuilder.buildFieldDoc(FieldBuilder.java:158)
  [javadoc]     at sun.reflect.GeneratedMethodAccessor51.invoke(Unknown Source)
  [javadoc]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  [javadoc]     at java.lang.reflect.Method.invoke(Method.java:597)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.FieldBuilder.invokeMethod(FieldBuilder.java:114)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:90)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.AbstractMemberBuilder.build(AbstractMemberBuilder.java:56)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.buildFieldDetails(ClassBuilder.java:301)
  [javadoc]     at sun.reflect.GeneratedMethodAccessor43.invoke(Unknown Source)
  [javadoc]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  [javadoc]     at java.lang.reflect.Method.invoke(Method.java:597)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.invokeMethod(ClassBuilder.java:101)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:90)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.buildClassDoc(ClassBuilder.java:124)
  [javadoc]     at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
  [javadoc]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  [javadoc]     at java.lang.reflect.Method.invoke(Method.java:597)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.invokeMethod(ClassBuilder.java:101)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:90)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.build(ClassBuilder.java:108)
  [javadoc]     at com.sun.tools.doclets.formats.html.HtmlDoclet.generateClassFiles(HtmlDoclet.java:155)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.generateClassFiles(AbstractDoclet.java:164)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.startGeneration(AbstractDoclet.java:106)
  [javadoc]     at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.start(AbstractDoclet.java:64)
  [javadoc]     at com.sun.tools.doclets.formats.html.HtmlDoclet.start(HtmlDoclet.java:42)
  [javadoc]     at com.sun.tools.doclets.standard.Standard.start(Standard.java:23)
  [javadoc]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  [javadoc]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
  [javadoc]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  [javadoc]     at java.lang.reflect.Method.invoke(Method.java:597)
  [javadoc]     at com.sun.tools.javadoc.DocletInvoker.invoke(DocletInvoker.java:215)
  [javadoc]     at com.sun.tools.javadoc.DocletInvoker.start(DocletInvoker.java:91)
  [javadoc]     at com.sun.tools.javadoc.Start.parseAndExecute(Start.java:340)
  [javadoc]     at com.sun.tools.javadoc.Start.begin(Start.java:128)
  [javadoc]     at com.sun.tools.javadoc.Main.execute(Main.java:41)
  [javadoc]     at com.sun.tools.javadoc.Main.main(Main.java:31)

Answer 1

Mixup in what version of the JDK is used?

Answer 2

It looks like this has been reported as a Java bug. It appears to be caused by using annotations from a 3rd party library (like JUnit) and not including the jar with that annotation in the javadoc invocation.

If that is the case, just use the -classpath option on javadoc and include the extra jar files.

Answer 3

I have some idea regarding this problem but this not exact soultion to get

If you give single comment line "\\" before annotation and try to run the javadoc once again. This problem will solve

Eg: sample.java File

@ChannelPipeline

Makes changes in

\\@ChannelPipeline

Try to run javadoc command once again. Now Class Cast Exception won't occur