Relationship design problem
Hi,
I have a design problem with two classes, just say class A and class B. The relationship of A and B is 1:n, which means one A object can hold many B objects. It is a aggregation not a composition, so one B object can be hold by different A objects. Both A and B are entity classes. Here is the problem : I want display a collection of A and B in a tree structure, e.g in JTree, A is the top level node and B is the second level node, I can navigate from A to B since in A I can use collection to hold B objects, but how to navigate from B to A? e.g. how to define the getParent() method in B? since one B may have several parents A objects, but in the tree view, the upper level node is the real parent which is what I want, how to capture this A object?
Thanks. Robin
[791 byte] By [
Zjga] at [2007-10-3 11:31:42]
You quite surely mix classes with instances :)
I would wonder, if an instance of B could be part of more than one instance of A, as, in this case, you would have a n:n relationship between A and B, which results in a graph, not a tree.
Your A will provide a variable of a subtype of Collection, I guess. and your B will have a container variable to take its parent instance of A.
Hi, stefan
the relation is n:n, let me give a real example, consider the relationship between organizations and persons. one organization can contain several persons, and one person can belong to serveral organization.
I want to display the relation in Tree, the top level is organization and the second is person. how to store parents info in person class or instance?
Zjga at 2007-7-15 13:58:23 >
Ok (you said differently in your first posting :)).
You try to display a graph as a tree, wich is quite difficult. I'd suggest to use seperate container classes (and thus instances) that hold a reference to the actual objects and only are used within the tree to represent "folders" and "leafs". folders would contain e.g. an organization and its leafs the persons.
