j2sdk1.4.1_01 rt.jar included some xerces/xalan parser to use. However, if I want to use the latest version of xalan, and put it in classpath, then I got a LoaderError: "XSLT Error (java.lang.LinkageError): loader constraints violated when linking org/xml/sax/InputSource class" Does anyone know how to solve the problem? Obviously, we cannot get rid of rt.jar. It seems pretty stupid to bundle them together to me. Any help will be appreciated very much.