Java Reference
In-Depth Information
9
Handling Common
Data Formats
Most of programming is handling data in various formats. In this chapter, we will
introduce Java's support for handling two big classes of data—text and numbers.
The second half of the chapter will focus on handling date and time information.
This is of particular interest as Java 8 ships a completely new API for handling date
and time. We cover this new interface in some depth, before finishing the chapter by
briefly discussing Java's original date and time API.
Many applications are still using the legacy APIs, so developers need to be aware of
the old way of doing things, but the new APIs are so much better that we recom‐
mend converting as soon as possible. Before we get to those more complex formats,
let's get underway by talking about textual data and strings.
Text
We have already met Java's strings on many occasions. They consist of sequences of
Unicode characters, and are represented as instances of the
String
class. Strings are
one of the most common types of data that Java programs process (a claim you can
investigate for yourself by using the
jmap
tool that we'll meet in
Chapter 13
).
In this section, we'll meet the
String
class in some more depth, and understand
why it is in a rather unique position within the Java language. Later in the section,
we'll introduce regular expressions, a very common abstraction for searching text
for patterns (and a classic tool in the programmer's arsenal).
Special Syntax for Strings
The
String
class is handled in a somewhat special way by the Java language. This is
because, despite not being a primitive type, strings are so common that it makes
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