the java documentation says : Hashtable.clone() Creates a shallow copy of this hashtable. The keys and values themselves are not cloned. This is a relatively expensive operation. What do u mean by shallow copy ?? Is it just means creating a new reference of the object or something more ??
A shallow copy in this case is a new hashtable, with one entry for each entry in the original hashtable, but the entries refer to the same keys and values as the original hashtable. for example, consider this sequence: