When the HBM. xml file is generated by middlegen, "Java. Lang. incompatibleclasschangeerror" is displayed.

Today, we use middlegen to generate HBM for hibernate. XML and java files. After the graphical interface is displayed, click the "generate" button and throw the "Java. lang. the incompatibleclasschangeerror error is confusing. Baidu looked at it and it seems that there are like-minded people, just like me, who successfully generated HBM when they were used for the first time. an error occurs when you use the XML file again.

Solution: there are multiple velocity-xxx.jar packages in the Lib package on which middlegen depends, and it is OK to delete the earlier version.