Dictionary Let's try and put the System Browser through it's paces. Select one of the Collection class Categories, and then select some of the protocols and methods and browse the comments . Click on some of the other classes in that category. Then look at the comments on the classes in the Collections-Unordered category. Remembers the order in which the objects where added.
Elements are accessible by external keys that are indices.
It can be used to implement queues and stacks. An ordered collection where the order is maintained automatically by sorted order rather than by the order of insertion. No duplicates allowed. An unordered collection of elements which remembers how many times and object has been added. Values can be duplicated but the keys must be unique.