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Posted to users@tomcat.apache.org by Thierry Thelliez <th...@earthlink.net> on 2002/07/14 02:04:28 UTC
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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RE: ClassCast exception
Posted by Thierry Thelliez <th...@earthlink.net>.
Problem fixed...
The problem was not with Tomcat but with the proprietary library used
(my class 'B').
At least I learned how Tomcat loads the classes... And the potential
issues with the class loaders.
Thanks again
Thierry
-----Original Message-----
From: Craig R. McClanahan [mailto:craigmcc@apache.org]
Sent: Saturday, July 13, 2002 8:42 PM
To: Tomcat Users List; thierry@acm.org
Subject: RE: ClassCast exception
On Sat, 13 Jul 2002, Thierry Thelliez wrote:
> Date: Sat, 13 Jul 2002 20:01:29 -0600
> From: Thierry Thelliez <th...@earthlink.net>
> Reply-To: Tomcat Users List <to...@jakarta.apache.org>,
thierry@acm.org
> To: 'Tomcat Users List' <to...@jakarta.apache.org>
> 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:craigmcc@apache.org]
> Sent: Saturday, July 13, 2002 7:57 PM
> To: Tomcat Users List; thierry@acm.org
> Subject: RE: ClassCast exception
>
>
>
> On Sat, 13 Jul 2002, Thierry Thelliez wrote:
>
> > Date: Sat, 13 Jul 2002 19:46:36 -0600
> > From: Thierry Thelliez <th...@earthlink.net>
> > Reply-To: Tomcat Users List <to...@jakarta.apache.org>,
> thierry@acm.org
> > To: 'Tomcat Users List' <to...@jakarta.apache.org>
> > 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:thelliez@earthlink.net]
> > Sent: Saturday, July 13, 2002 6:04 PM
> > To: tomcat-user@jakarta.apache.org
> > 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
> >
> >
> > --
> > To unsubscribe, e-mail:
> > <ma...@jakarta.apache.org>
> > For additional commands, e-mail:
> > <ma...@jakarta.apache.org>
> >
> >
> > --
> > To unsubscribe, e-mail:
> <ma...@jakarta.apache.org>
> > For additional commands, e-mail:
> <ma...@jakarta.apache.org>
> >
> >
>
>
> --
> To unsubscribe, e-mail:
> <ma...@jakarta.apache.org>
> For additional commands, e-mail:
> <ma...@jakarta.apache.org>
>
>
> --
> To unsubscribe, e-mail:
<ma...@jakarta.apache.org>
> For additional commands, e-mail:
<ma...@jakarta.apache.org>
>
>
--
To unsubscribe, e-mail: <ma...@jakarta.apache.org>
For additional commands, e-mail: <ma...@jakarta.apache.org>
RE: ClassCast exception
Posted by "Craig R. McClanahan" <cr...@apache.org>.
On Sat, 13 Jul 2002, Thierry Thelliez wrote:
> Date: Sat, 13 Jul 2002 20:01:29 -0600
> From: Thierry Thelliez <th...@earthlink.net>
> Reply-To: Tomcat Users List <to...@jakarta.apache.org>, thierry@acm.org
> To: 'Tomcat Users List' <to...@jakarta.apache.org>
> 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:craigmcc@apache.org]
> Sent: Saturday, July 13, 2002 7:57 PM
> To: Tomcat Users List; thierry@acm.org
> Subject: RE: ClassCast exception
>
>
>
> On Sat, 13 Jul 2002, Thierry Thelliez wrote:
>
> > Date: Sat, 13 Jul 2002 19:46:36 -0600
> > From: Thierry Thelliez <th...@earthlink.net>
> > Reply-To: Tomcat Users List <to...@jakarta.apache.org>,
> thierry@acm.org
> > To: 'Tomcat Users List' <to...@jakarta.apache.org>
> > 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:thelliez@earthlink.net]
> > Sent: Saturday, July 13, 2002 6:04 PM
> > To: tomcat-user@jakarta.apache.org
> > 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
> >
> >
> > --
> > To unsubscribe, e-mail:
> > <ma...@jakarta.apache.org>
> > For additional commands, e-mail:
> > <ma...@jakarta.apache.org>
> >
> >
> > --
> > To unsubscribe, e-mail:
> <ma...@jakarta.apache.org>
> > For additional commands, e-mail:
> <ma...@jakarta.apache.org>
> >
> >
>
>
> --
> To unsubscribe, e-mail:
> <ma...@jakarta.apache.org>
> For additional commands, e-mail:
> <ma...@jakarta.apache.org>
>
>
> --
> To unsubscribe, e-mail: <ma...@jakarta.apache.org>
> For additional commands, e-mail: <ma...@jakarta.apache.org>
>
>
--
To unsubscribe, e-mail: <ma...@jakarta.apache.org>
For additional commands, e-mail: <ma...@jakarta.apache.org>
RE: ClassCast exception
Posted by Thierry Thelliez <th...@earthlink.net>.
Thanks Craig for correcting my forName() mistake.
But do you have any suggestions for the casting issue?
Regards,
Thierry
-----Original Message-----
From: Craig R. McClanahan [mailto:craigmcc@apache.org]
Sent: Saturday, July 13, 2002 7:57 PM
To: Tomcat Users List; thierry@acm.org
Subject: RE: ClassCast exception
On Sat, 13 Jul 2002, Thierry Thelliez wrote:
> Date: Sat, 13 Jul 2002 19:46:36 -0600
> From: Thierry Thelliez <th...@earthlink.net>
> Reply-To: Tomcat Users List <to...@jakarta.apache.org>,
thierry@acm.org
> To: 'Tomcat Users List' <to...@jakarta.apache.org>
> 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:thelliez@earthlink.net]
> Sent: Saturday, July 13, 2002 6:04 PM
> To: tomcat-user@jakarta.apache.org
> 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
>
>
> --
> To unsubscribe, e-mail:
> <ma...@jakarta.apache.org>
> For additional commands, e-mail:
> <ma...@jakarta.apache.org>
>
>
> --
> To unsubscribe, e-mail:
<ma...@jakarta.apache.org>
> For additional commands, e-mail:
<ma...@jakarta.apache.org>
>
>
--
To unsubscribe, e-mail:
<ma...@jakarta.apache.org>
For additional commands, e-mail:
<ma...@jakarta.apache.org>
--
To unsubscribe, e-mail: <ma...@jakarta.apache.org>
For additional commands, e-mail: <ma...@jakarta.apache.org>
RE: ClassCast exception
Posted by "Craig R. McClanahan" <cr...@apache.org>.
On Sat, 13 Jul 2002, Thierry Thelliez wrote:
> Date: Sat, 13 Jul 2002 19:46:36 -0600
> From: Thierry Thelliez <th...@earthlink.net>
> Reply-To: Tomcat Users List <to...@jakarta.apache.org>, thierry@acm.org
> To: 'Tomcat Users List' <to...@jakarta.apache.org>
> 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:thelliez@earthlink.net]
> Sent: Saturday, July 13, 2002 6:04 PM
> To: tomcat-user@jakarta.apache.org
> 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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RE: ClassCast exception
Posted by Thierry Thelliez <th...@earthlink.net>.
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)
( b.getClass().getClassLoader()) ==
Class.forName("p2.A").getClassLoader())); -> true
( b.getClass().getClassLoader()) ==
Class.forName("A").getClassLoader())); -> Class not found...
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
-----Original Message-----
From: Thierry Thelliez [mailto:thelliez@earthlink.net]
Sent: Saturday, July 13, 2002 6:04 PM
To: tomcat-user@jakarta.apache.org
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
--
To unsubscribe, e-mail:
<ma...@jakarta.apache.org>
For additional commands, e-mail:
<ma...@jakarta.apache.org>
--
To unsubscribe, e-mail: <ma...@jakarta.apache.org>
For additional commands, e-mail: <ma...@jakarta.apache.org>