Update binary file using ObjectOutputStream

Question

Am writing three objects to a binary file using below code in java.

oout = new ObjectOutputStream(new FileOutputStream(fileName));
oout.writeObject(objClass1);             
oout.writeObject(objClass2);              
oout.writeObject(objClass3);

Then how can i want to modify some data in the objClass1 and update the file? Also append objClass3 to the end of file.

Thanks....

Evgeniy Dorofeev · Accepted Answer · 2013-05-08 07:38:46Z

3

You cannot update just one object, you need to overwrite the whole file. Read all 3 objects from file then write them back with new objClass1 version

edited May 8, 2013 at 7:38

answered May 8, 2013 at 7:27

Evgeniy Dorofeev

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Stephan · Accepted Answer · 2013-05-08 07:42:51Z

1

You cannot write at the beginning of a file that has contents so you need to read the content , update what you want and write again all the content... this isn't very efficient so i propose 2 solutions :

write each object to a separate file
use a object store like HashStore , Neodatis, db4o etc
you can use a rdms to store the objects (BLOB type in mysql) in a serialized way

edited May 8, 2013 at 7:42

answered May 8, 2013 at 7:29

Stephan

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