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)

Jeromyjerreed

Mixup in what version of the JDK is used? – Eupatorium

Answer 1

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.

Rumsey

This worked for me. locate junit turned up lots, so I picked one at random, put it on the classpath, and that particular exception went away. I still think javadoc is ridiculously flakey, considering how widely it's used. – Iconium

For me, I had to add the Jackson libraries to the javadoc classpath. – Wittenburg

I had to add annotations.jar to my classpath, which is in the android-sdk/tools/support directory – Radio

Answer 2

I have some idea regarding this problem but this not exact solution 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 ClassCastException won't occur.

Tibia

Answer 3

There is another way to get a ClassCastException in versions of Java from 5 through 8:

java.lang.ClassCastException: com.sun.tools.javadoc.MethodDocImpl cannot be cast to com.sun.tools.javadoc.AnnotationTypeElementDocImpl

It will happen when javadoc encounters a reference to a annotation method in javadoc text before processing the same annotation for the first time used in code. Take these two classes:

/**
 ** {@link javax.annotation.Generated#value()}
 */
public class TestClass1 {}


@Generated("sometext")
public class TestClass2 {}

The bug is order dependent. If javadoc processes TestClass1 first, the ClassCastException will be thrown. If javadoc processes TestClass2 first, it will complete fine. The bug is reported as JDK-8170444, and was resolved as "Won't Fix". The bug is no longer present in Java 9.

As a workaround, don't link to annotation methods in your documentation text.

Bluecoat

I ran into exactly this issue myself in some code that needs to be compiled against Java 8. I get this error when running Javadoc with Java 8, but not with Java 9. – Sidon

Answer 4

I got this problem too. I can compile properly without any errors or warnings. But when I generating javadoc , I got below error.

[javadoc] java.lang.ClassCastException: com.sun.tools.javadoc.ClassDocImpl cannot be cast to com.sun.javadoc.AnnotationTypeDoc

Here is my classpath loading for my third-party-libs ...

<path id="build.classpath">
<fileset dir=".">
    <include name="libs/*.jar" />
</fileset>

At my java compile target ..

<target name="compile" depends="clean, makedir">
<javac includeantruntime="false" srcdir="${src.dir}" destdir="${build.dir}" classpathref="build.classpath">
  <compilerarg value="-Xlint:unchecked"/>
</javac>

And at my javadoc target...

<target name="docs" depends="compile">
<javadoc packagenames="src" sourcepath="${src.dir}" destdir="${docs.dir}" 
    failonerror="no"
    author="true"
    version="true"
    windowtitle="${Name} API"
    doctitle="${Name}"
    bottom="Copyright © 2014 ColayHIlls.com . All Rights Reserved.">
   <fileset dir="${src.dir}">
            <include name="main/java/com/colayhills/jpcenter/business/service/**" />
   </fileset>
</javadoc>
<echo message="java docs has been generated!"/>
</target>

So , I added classpathref="build.classpath" option to <javadoc tag. Now It is fine for me.

Aliciaalick