Structuring Data with Java - Java - page 231

Beware of some typographic issues. The word Arrays (in constant width font) is short for
the class java.util.Arrays , but in the normal typeface, the word “arrays” is simply the
plural of “array” (and will be found capitalized at the beginning of a sentence). Also, note
that HashMap and HashSet follow the rule of having a “midcapital” at each word boundary,
whereas the older Hashtable does not (the “t” is not capitalized).
The java.util package has become something of a catch-all over the years. Besides the leg-
acy Date/Time API covered in Interfacing with Legacy Date and Calendar Classes , several
other classes from java.util are not covered in this chapter. All the classes whose names
begin with Abstract are, in fact, abstract, and we discuss their nonabstract subclasses. The
StringTokenizer class is covered in Breaking Strings Into Words . BitSet is used less fre-
quently than some of the classes discussed here and is simple enough to learn on your own; I
have examples of it in Recipes and . BitSet stores the bits very compactly in memory, but
because it predates the Collection API and wasn't retrofitted, it doesn't implement any of the
standard collection interfaces. Also here are EnumSet and EnumMap , specialized for efficient
storage/retrieval of enums. These are newer than BitSet and do implement the modern col-
lection interfaces.
We start our discussion of data structuring techniques with one of the oldest structures, the
array. We discuss the overall structure of java.util 's Collections Framework. Then we'll
go through a variety of structuring techniques using classes from java.util .
Using Arrays for Data Structuring
Problem
You need to keep track of a fixed amount of information and retrieve it (usually) sequen-
tially.
Solution
Use an array.