Java Collections Framework - Building Java Programs: A Back to Basics Approach - page 706

The program produces the following output for Moby Dick:

This program displays the most
frequently occurring words from
the book Moby-Dick.

a occurs 4509 times.
and occurs 6138 times.
his occurs 2451 times.
in occurs 3975 times.
of occurs 6405 times.
that occurs 2705 times.
the occurs 13991 times.
to occurs 4433 times.

Collection Overview
We've discussed three major abstract data types in this chapter: lists, sets, and maps.
It's important to understand the differences between them and to know when each
should be used. Table 11.6 summarizes the different types of collections and their
pros and cons.
When you approach a new programming problem involving data, you can ask
yourself questions to decide what type of collection is most appropriate. Here are
some examples:

• What are you going to do with the data? Do you intend to add and remove many

elements, search the data many times, or connect this data to other data?

Table 11.6 Comparison of Lists, Sets, and Maps

ADT Implementations Description/Strengths Weaknesses Example Usages

A sequence of elements Slow to search, slow List of accounts;

List ArrayList,

arranged in order of to add/remove prime numbers; LinkedList

insertion arbitrary elements the lines of a file

A set of unique Does not have indexes; Unique words in

Set HashSet,

elements that can be user cannot retrieve a book; lottery TreeSet

searched quickly arbitrary elements ticket numbers

A group of associations Not a general-purpose Word counting;

Map HashMap,

between pairs of “key” collection; cannot easily phone book TreeMap

and “value” objects map backward from creation

a value to its key