The use of null values in a map is problematic, as there is then no way to differentiate whether a null value returned by the call get( k ) represents the legitimate value of an entry (k, null ), or designates that key k was not found. The java.util. Map interface includes a boolean method, containsKey (k), that resolves any such ambiguity. Implement such a method for the Unsorted TableMap class. | Numerade