Java – Difference between a HashMap and a dictionary ADT


What is the difference between a Hash Map and dictionary ADT. And when to prefer one over another. For my programming assignment my instructor has asked to use one of them but I don't see any difference in between both. The program is supposed to work with a huge no. of strings. Any suggestions?

Best Solution

In terms of Java, both the class HashMap and the class Dictionary are implementations of the "Map" abstract data type. Abstract data types are not specific to any one programming language, and the Map ADT can also be known as a Hash, or a Dictionary, or an Associative Array (others at (Notice we're making a distinction between the Dictionary class and the Dictionary ADT.)

The Dictionary class has been marked as obsolete, so it's best not to use it.