Tomcat deployment problem using jar file instead of classes

Question

We're deploying a WAR file into Tomcat 5.5 and it works fine if WEB-INF\classes contains .classes files, but if we move the .jar file containing that .classes into WEB-INF\lib, we get an exception on runtime complaining that java.lang.NoSuchMethodError, but existing class file in .jar file contains the class and method does exits!

Any help on this would be appreciated.

Answer 1

This could be caused due to a class conflict. Make sure that there isn't an older version of the Class somewhere (Tomcat's shared folder, WEB-INF/classes, WEB-INF/lib). If this is the case, you practically can't know which class Tomcat will load. If it picks one without the method, the exception you are experiencing will occur.

Answer 2

Since you are getting a NoSuchMethodError, and not a ClassNotFoundError, it means that you have an old version of the class somewhere (outside of the jar file). You need to find and remove it.