This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
If we don't implement serializable interface, what will it happen?
Easy question to answer: you can't serialize the object. Most people producing code for use in the "real world" would implement the Serializable interface on spec, because you can get a NonSerializableException if you try to serialize an instance whose fields are not all serializable.
There is another mechanism for (long-term) object persistence: use of JavaBeans. I hardly know anything about them