Question

Is it possible to have multiple classes that inherit/extends same class in Google AppEngine with Java (GAE/J) for my entities (JDO).
For example I have:

• Content (Abstract class)
• Course

and then my Course will have :

• list of Video that is extends Content
• list of Books

At the same time

• Video has list of Tags
• Book has list of Tags
• Course has list of Tags

Is it possible to do it GAE?

I’m doing similar to this but having so much problems. Is there any examples of this kind of stuff?

Answer 1

Update based on new question title

I still don’t understand what your difficulty is, but I will give it a shot

Your question is

Is it possible to have multiple
classes that inherit/extends same
class in Google AppEngine with Java
(GAE/J) for my entities

The answer is yes, why not? I don’t see anything in your question that can’t be done. What problem are you having?

I’m doing similar to this but having
so much problems. Is there any
examples of this kind of stuff?
How are you doing it exactly, because I can’t see anything wrong with the description you posted.

and just to help you out, here is one way it can be done,

interface Tagable {
 public doSomeThingWithTagList(); 
} 

class abstract Content implements Tagable {
 List<Tag> tagList; 
} 

class Video extend Content implements Tagable {
} 

class Book Tagable{ 
 List<Tag> tagList; 
} 

class Course Tagable {
   List<Video> videoList;
   List<Books> bookList;
   List<Tag> tagList 
}