Size Of Using Serialization

Question

Hi I would like to implement a size of method in Java. I know it is impossible but I also know that there are turn arounds to the problem using methods such as gc and serialization which give satiffactory results.
In my case acurracy is not of utmost importance but speed is. The sizeOf method will be used in a object caching service and will be called each time an object is put in the cache.
I thought that serialization would be a good option. Do you guys think it is the best one? And if yes how can I go around finding the size of the serializaed stream without writing it to disk.
My main goal would be to turn the following code to write the serialzation to a String instead of the file in order to eliminate disk
IO.
BaseCacheReference B = new BaseCacheReference(new Attributes());
FileOutputStream f_out = new FileOutputStream ("C:\\myobject.data");
ObjectOutputStream obj_out = new ObjectOutputStream (f_out);
obj_out.writeObject (B);
Can anyone help me?
Thanks in Advance
Nick.

Answer 1

Thanks guys and girls,
TO SYLVIA:
I am trying to create a cache engine with different policies such as GC based using soft references
and also my own using LRU, LFU methods. The cache will be used to cache objects that are expensive
to create. Thus it is simple object caching. (theOCS4J specification is similar to what I have in mind)
The cache will be sub-divided into what I called regions of memory
sizes specfied by the user. Each region uses one of the above policies to clear the cache when it reaches its limit.
Now my problem is how can I determine if my region has reached the limit without knowing the size of the objects
being added to the cache.
TO forumNazi:
DO YOU GET THE POINT forumNazi or where you simply just stoned when you read the message? Anyway
could you pls avoid writing useless messages in the near fututure pls since they don'nt get
any of us in a better position.
Back to the problem!! I tried using the ByteArrayOutputStream as DrJohnFoster said
and created the following function:
public int sizeOf(CacheReference CacheObject)
          try
               ByteArrayOutputStream baos = new
ByteArrayOutputStream();
               ObjectOutputStream out = new ObjectOutputStream(baos);
               out.writeObject(CacheObject);
               out.flush();
               // Subtract 4 bytes from the length, because the serialization
               // magic number (2 bytes) and version number (2 bytes) are
               // both written to the stream before the object
               return baos.toByteArray().length - 4;
          catch(IOException e)
               System.out.println(e);
               return 0;
Since you said that serialization includes stuff such as class names, field names then I guess
I could either find an aprroximation to the size of the object by trying to calculate the
amount of mem used in field names, OR I could resort reflection.
I don'nt know if it is possible but could you post me a copy of the code of the sizeOf() using
reflection sylvia.
Thanks to ALL