Hi there, is it valid to have a java class name and file as

public class DVD extends Items{

and

public class CD extends Items{

where its all in capitals?

-thanks, sorry for the short question.

No problem. The Java coding standard just says the class names should begin with a capital letter, but if you have deeper questions about Java coding standards or conventions I recommend that you use the Java API as your guide - that's a huge amount of code that demonstrates every variation youu will ever need.
So, for example, you will see that the API includes classes like: CRC32, CSS and URL. You can safely conclude that if the class name is an ancronym that's normally capitalised, it's appropriate to capitalise the class name in the same way.