On Sat, 13 Jul 2002, Thierry Thelliez wrote:
> Date: Sat, 13 Jul 2002 20:01:29 -0600
> From: Thierry Thelliez <[EMAIL PROTECTED]>
> Reply-To: Tomcat Users List <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
> To: 'Tomcat Users List' <[EMAIL PROTECTED]>
> Subject: RE: ClassCast exception
>
> Thanks Craig for correcting my forName() mistake.
>
> But do you have any suggestions for the casting issue?
>
What's the return type of doSomething()? I presume it returns a B?
The most reliable way to cause a ClassCastException is if A is *not*
really a subclass of B :-). If you accidentally made this mistake,
putting them in the same JAR or things like that wouldn't have mattered
anyway.
>
> Regards,
> Thierry
>
Craig
> -----Original Message-----
> From: Craig R. McClanahan [mailto:[EMAIL PROTECTED]]
> Sent: Saturday, July 13, 2002 7:57 PM
> To: Tomcat Users List; [EMAIL PROTECTED]
> Subject: RE: ClassCast exception
>
>
>
> On Sat, 13 Jul 2002, Thierry Thelliez wrote:
>
> > Date: Sat, 13 Jul 2002 19:46:36 -0600
> > From: Thierry Thelliez <[EMAIL PROTECTED]>
> > Reply-To: Tomcat Users List <[EMAIL PROTECTED]>,
> [EMAIL PROTECTED]
> > To: 'Tomcat Users List' <[EMAIL PROTECTED]>
> > Subject: RE: ClassCast exception
> >
> >
> > More details to the problem described in the first email.
> >
> > I have now tried another scenario:
> >
> > My parent class (B) is now sitting in a jar in WEB-INF/lib.
> > My subClass (A) is in a .class in WEB-INF/classes.
> > B and A are in different packages (p1.x.B and p2.A).
> >
> > The code with the casting issue is in a static method of A.
> >
> > B b = doSomething(); -> Works
> >
> > log("B " + b.getClass().getName()); -> p1.x.B
> > log("B " + b.getClass().getClassLoader()); -> CL1
> >
> > log("A " + A.class.getClassLoader()); -> CL2 (seems to be
> =
> > to CL1)
> >
>
> That will generally be true -- the container sets up a single class
> loader
> for everything in WEB-INF/classes and WEB-INF/lib.
>
> > ( b.getClass().getClassLoader()) ==
> > Class.forName("p2.A").getClassLoader())); -> true
> >
> > ( b.getClass().getClassLoader()) ==
> > Class.forName("A").getClassLoader())); -> Class not
> found...
>
> This is never going to work. The argument to Class.forName has to be
> the
> fully qualified class name. See the Javadocs on java.lang.Class for
> more.
>
> >
> > A a = (A) doSomething(); ->
> > ClassCastException...
> >
> >
> >
> > I have been through extensive web search. It seems that this problem
> is
> > not uncommon but I cannot figure out how to solve it...
> >
> > (How do you get the instance id for the ClassLoaders? In the output in
> > my first email, my class loaders are giving me a name, not a unique
> id)
> >
> > Help!
> >
> > Thierry
> >
>
> Craig
>
>
> > -----Original Message-----
> > From: Thierry Thelliez [mailto:[EMAIL PROTECTED]]
> > Sent: Saturday, July 13, 2002 6:04 PM
> > To: [EMAIL PROTECTED]
> > Subject: ClassCast exception
> >
> > Hello,
> >
> > I have a ClassCast problem. I read the archive and attempted few
> > suggestions (like grouping everything in one jar in WEB-INF/lib)
> without
> > success.
> >
> > I am using tomcat 4.0.4 and 1.3.1_02 under Solaris.
> >
> > Someone suggested looking at the ClassLoaders. The following is
> > generated by something like:
> > Log4j("MyClass " + MyClass.class.getClassLoader());
> >
> > --------------------------------------------------------------------
> > 2002-07-13 18:36:56,808 - - MyClass WebappClassLoader
> > available:
> > delegate: false
> > repositories:
> > required:
> > ----------> Parent Classloader:
> > StandardClassLoader
> > available:
> > delegate: true
> > repositories:
> > file:/serverPath/jakarta-tomcat-4.0.4/classes/
> > file:/serverPath/jakarta-tomcat-4.0.4/lib/jasper-runtime.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/lib/jasper-compiler.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/lib/naming-factory.jar
> > required:
> > ----------> Parent Classloader:
> > StandardClassLoader
> > available:
> > Extension[javax.mail, implementationVendor=Sun Microsystems, Inc.,
> > implementationVendorId=com
> > .sun, implementationVersion=1.2, specificationVendor=Sun Microsystems,
> > Inc., specificationVersion
> > =1.2]
> > delegate: true
> > repositories:
> > file:/serverPath/jakarta-tomcat-4.0.4/common/classes/
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/naming-common.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/servlet.jar
> >
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/naming-resources.jar
> >
> file:/serverPath/jakarta-tomcat-4.0.4/common/lib/jdbc2_0-stdext.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/activation.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/jta-spec1_0_1.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/xerces.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/tyrex-0.9.7.0.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/mail.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/jndi.jar
> > file:/serverPath/jakarta-tomcat-4.0.4/common/lib/cos.jar
> > required:
> > ----------> Parent Classloader:
> > sun.misc.Launcher$AppClassLoader@3f52a5
> >
> >
> > ---------------------------------
> >
> > just after that I try a Class.forName("MyClass");
> > but I get a ClassNotFound exception.
> >
> >
> > Is that normal that I don't see listed the webapps/myApp/WEB-INF/lib
> in
> > the repositories above?
> >
> > In the ClassCast issue, both classes return the same loader.
> >
> > Thanks,
> > Thierry
> >
> >
> > --
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