hi, as I know, during requirement specification and design stages, there is diagram flow: use case->use case diagram->sequence Diagram->collaboration diagram->class diagram. Does the class diagram come at the end? not during those stages? Thanks
You can't draw a sequence diagram without having identified the classes and you can't fully draw the class diagrams until you have identified the methods from the sequence diagram. So... it is a back and forth process of refining each of the diagrams as you gain a greater understanding of the application.
try a flow more like create use case diagrams -> create a conceptual model(class diagram with out the methods) -> create sequence Diagram-> create collaboration diagram->class diagram(with the methods!).