I think it is alright to add additional methods in the Data class. If you take a look at the methods of the DBAccess interface, there are methods that are redundant and there are some functions that your program needs but are not specified by the interface. The specification does not say anything like you
must not create new methods in the Data class. I had four additional methods that I feel is neccessary to meet the
must requirements at my user interface section.
I implemented all the methods in the DBAccess method but only use the unlock and lockRecord method in a class I call DataManipulator that provide access to the Data class. I believe that if you feel that there is a need for additional methods, you can just add it in, and be sure that you justify why you do that. I think that is how the General Considerations points come from.
I hope my humble opinion helps. Anyone who had passed
SCJD can help in this topic? Thanks.