When using Java’s Map implementations, it is sometimes common to invoke the Map ‘s get (Object) method and to react differently based on whether the value returned is null or not.

Listing 3 Type-safe Map In the class hierarchy of the Java Collections library, the Map interface acts independently of the Collection interfaces Collection, List, Set, and SortedSet.

HashMap vs. Hashtable similarities Both the Hashtable and HashMap implement the Map interface and both share the same set of methods used to add, remove and manipulate elements of a key-value, ...