JAVA class implementation and extension issues

Question

We have 2 JAVA classes related to a project, call them AGraph and CallGraph. We also have an interface named Graphism which is implemented by AGraph. There's one abstract class we have, named GraphSnippet, which basically creates a visualization of a ZEST graph.

Now, we want CallGraph to extend AGraph. My silly doubt here is, does CallGraph need to implement the interface Graphism as well?

Next, instead of making GraphSnippet an instance of the Graph class (Graph is a pre-defined class in the ZEST package), we want it to be an instance of CallGraph so that the functionalities of CallGraph and AGraph become a part of the implementation. And because we'll need the class AGraph during the later stages, we can't really knock this class out and get all its methods implemented in CallGraph.

Could someone help us with how to start with it? It's difficult for us, novice JAVA programmers, to figure out a way?

PS: We're working on Eclipse-JUNO.

Answer 1

Now, we want CallGraph to extend AGraph. My silly doubt here is, does CallGraph need to implement the interface Graphism as well?

Yes, but you won't have to do anything. Because it extends from AGraph, it will already implement Graphism. You won't have to mark this anywhere in your code.