AW: [OJB-developers] OJB ManageableCollection ?

[Mahler T. <tho...@it...>]

Hi Jakob,
=20
the ManageableCollection interface maybe helpful if you don't want to =
(or
can't)  implement 1:n association with java.util.Collection derived =
classes
or with arrays.
A typical example are user defined typed collections. See sample code =
from
package test.ojb.broker below. There is a ProductGroup class with a
collection implementor=20
allArticlesInGroup of type ArticleCollection.
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Class ArticleCollection only allows typed access (as opposed to the =
untyped
access with java.util.Collection).
You can add only InterfaceArticle objects and with get(...) you =
retrieve
InterfaceArticle objects from the collection.
=20
OJB must interact with such user defined collections in a standardized =
way.
That's the reason for the callback interface ManageableCollection. It
provides elementary access to the user defined collection for the
materialisation process and for update and delete routines (through
ojbIterator()).
=20
HTH,
=20
Thomas
=20
public class ProductGroupWithTypedCollection
{
    // ...
=20
    /** collection containing all articles of a given product group*/
    private ArticleCollection allArticlesInGroup;

    // ...
}
=20
public class ArticleCollection implements ManageableCollection
{
    private Vector elements;
=20
    /**
     * ArticleCollection constructor comment.
     */
    public ArticleCollection()
    {
        super();
        elements =3D new Vector();
    }
=20
    public void add(InterfaceArticle article)
    {
        if (elements =3D=3D null)
            elements =3D new Vector();
        elements.add(article);
    }
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    public InterfaceArticle get(int index)
    {
        return (InterfaceArticle) elements.get(index);
    }
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    /**
     * add method comment.
     */
    public void ojbAdd(java.lang.Object anObject)
    {
        elements.add((InterfaceArticle) anObject);
    }
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    /**
     * addAll method comment.
     */
    public void ojbAddAll(ojb.broker.ManageableCollection =
otherCollection)
    {
        elements.addAll(((ArticleCollection) =
otherCollection).elements);
    }
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    /**
     * ojbIterator method comment.
     */
    public java.util.Iterator ojbIterator()
    {
        return elements.iterator();
    }
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    public int size()
    {
        return elements.size();
    }
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    public String toString()
    {
        return elements.toString();
    }
}
=20
=20

-----Urspr=FCngliche Nachricht-----
Von: Jakob Braeuchi [mailto:jbr...@ho...]
Gesendet: Dienstag, 18. Dezember 2001 08:33
An: Objectbridge Developers List (E-mail)
Betreff: [OJB-developers] OJB ManageableCollection ?


hi,
=20
while working on the proxy-collection, i came across the
ManageableCollection.
i do not know what they are needed for, the three methods defined in =
this
interface are also defined (without ojb prefix) in Collection.
=20
jakob