Re: [OJB-developers] OJB ManageableCollection ?

[Jakob B. <jbr...@ho...>]

hi thomas,

thank you for clarification. i now understand the intention to have =
those collections and i'll try to find a way to support lazy collection =
there too. (eventually with a new interface ProxyManageableCollection)=20
i think the current implementation of ProxyCollection should not be used =
for ManageableCollection.

jakob
  ----- Original Message -----=20
  From: Mahler Thomas=20
  To: 'Jakob Braeuchi' ; Objectbridge Developers List (E-mail)=20
  Sent: Tuesday, December 18, 2001 9:11 AM
  Subject: AW: [OJB-developers] OJB ManageableCollection ?


  Hi Jakob,

  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.

  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.

  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()).

  HTH,

  Thomas

  public class ProductGroupWithTypedCollection
  {
      // ...

      /** collection containing all articles of a given product group*/
      private ArticleCollection allArticlesInGroup;

      // ...
  }

  public class ArticleCollection implements ManageableCollection
  {
      private Vector elements;

      /**
       * ArticleCollection constructor comment.
       */
      public ArticleCollection()
      {
          super();
          elements =3D new Vector();
      }

      public void add(InterfaceArticle article)
      {
          if (elements =3D=3D null)
              elements =3D new Vector();
          elements.add(article);
      }

      public InterfaceArticle get(int index)
      {
          return (InterfaceArticle) elements.get(index);
      }

      /**
       * add method comment.
       */
      public void ojbAdd(java.lang.Object anObject)
      {
          elements.add((InterfaceArticle) anObject);
      }

      /**
       * addAll method comment.
       */
      public void ojbAddAll(ojb.broker.ManageableCollection =
otherCollection)
      {
          elements.addAll(((ArticleCollection) =
otherCollection).elements);
      }

      /**
       * ojbIterator method comment.
       */
      public java.util.Iterator ojbIterator()
      {
          return elements.iterator();
      }

      public int size()
      {
          return elements.size();
      }

      public String toString()
      {
          return elements.toString();
      }
  }


    -----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,

    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.

    jakob