Hi,
Welcome to JavaRanch!
I'm not sure I understand your question: it sounds like you're saying that if you write out an object, change it, then read it back in, the changes get overwritten; but of course that can't be what you're saying, because surely that's the behavior you'd expect.
Can you try to rephrase your question?
Also, this has nothing to do with performance; I'm going to move it to
I/O and Streams [ October 13, 2003: Message edited by: Ernest Friedman-Hill ]