Only new Instance of object is serializable?

[Ben Flowers]

Hi Basicaly im trying to save my object to file, but im getting a NotSerializableException
However if i create a new object then it works fine.

				objStream.writeObject(new Checkout());
				objStream.writeObject(oldCheckout);

the above code fails on the second line but the first runs?
Does anyone knwo why this is happening or how i can fix this?
Thanks,
Ben

[Rob Spoor]

Your old object probably has a field that is not serializable. When an object is serialized, all of its non-transient fields are also serialized, and therefore these must be serializable as well.

[Paul Clapham]

And if you look at the error message more carefully, you will notice that it mentions the name of the class which was not serializable.