java.lang.ClassCastException: com.example.deyunwulian.entity.Data cannot be cast to com.example.deyunwulian.entity.Role

This error occurs when you try to cast an object of type "Data" to an object of type "Role". This means that the object you're trying to cast is not an instance of the "Role" class, and therefore cannot be treated as such.

To fix this error, you should check the type of the object before attempting to cast it. You can do this using the "instanceof" operator, like this:

if (myObject instanceof Role) {
Role myRole = (Role) myObject;
// Do something with myRole
} else {
// Object is not a Role
}

This code checks if "myObject" is an instance of the "Role" class, and if it is, it casts it to a "Role" object. If it's not a "Role" object, you can handle the error accordingly.