ImmutableArrayList default for Map Long, Collection String

Question

Hi,
There are a few topics out there about the com.tangosol.util.ImmutableArrayList default, but the actual fix still seems a bit unclear to me.
In my example there is a Map with each entry containing a Collection of Strings (i.e. Map<Long, Collection<String>>). Objects will be placed in the Map as ArrayLists, but they seem to come out as ImmutableArrayLists.
The Oracle site mentions wrapping the Collection (http://extranet.tangosol.com/display/COH35UG/Best+Practices+for+Coherence+Extend).
There is another Oracle forum post that suggests using more general classes (List instead of ArrayList). (Serialize an ArrayList<ArrayList>
It seems like you have to make a new collection anytime you wish to reserialize the object. Is there a better way?
Thanks for taking the time,
Mike

Answer 1

This problem comes up for us when persisting documents. We are torn between saving as XML vice saving a normalized object model or something else: like your database solution.
Since you have already designed the database, then you can reverse out the TopLink class from that database design in the mapping workbench. You then have to perform a transform in the middle tier to extract your business model.
Alternatively, if you want your business model to map via ORM to the data model, then you would have a database design that more closely maps the business model design then you get three tables:
TopLevel
Integer primaryKey; //This table may just have the PK
SetMap theSets;
SetMap
TopLevel parent; //FK to the Parent table
Long primaryKey; //Assumes the Longs are globally unique. If not, the PK will include the parent
SetList theSet;
SetList
SepMap parent; //Part of PK. This can get complicated if the PK migrates all the way from TopLevel. We insert a surrogate key at this point.
String setMember; //Rest of PK
The database constraints ensure that the SetList is unique. The equivalent string may exist in different SetMaps, but may not be duplicated for a particular parent.