Just Java™ 2

Writing Objects to Disk

We've already seen how to write out strings, ints, doubles, etc., in both printable and binary forms. It may surprise you to learn that you can also write out, and later read back in, entire objects. When you serialize (write out) a single object to a data stream, it automatically saves the object, namely, all its instance data. If any of these non-static fields reference other objects, those objects are serialized too. That way, when you later deserialize (restore) the object, you get back the object and all its member fields pointing to all the things they pointed to before—everything needed to reconstitute the original object.

For example, if you serialize one element of a doubly linked list, everything it references, ...