Serializing a Singleton

I have been forwarded some study material on Core Java related stuff from The Training Group in my Organization to prepare for a forthcoming training program. While going thro it, I came across an interesting point of which I was unaware earlier. It relates to Singleton classes. While dicussing Singleton classes, it says that

To make a singleton class serializable provide a readResolve method. Otherwise, each deserialization of a serialized instance will result in the creation of a new instance.

public class CacheMgr {
    public static final CacheMgr INSTANCE = new CacheMgr();

    private CacheMgr() {
        // ...
    }

    // ...  // Remainder omitted

    // readResolve method to preserve singleton property
    private Object readResolve() throws ObjectStreamException {
        /*
         * Return the one true CacheMgr and let the garbage collector
         * take care of the CacheMgr impersonator.
         */
        return INSTANCE;
    }

    public static void main(String[] args) {
        System.out.println(CacheMgr.INSTANCE);
    }
}

I have not thought of this aspect so far. So, obviously, I have no experience of it either. However, I am interesting to know if you know an idea on the subject. Any first hand experience?