CHAPTER 15 ■ GENERICS AND REGULAR EXPRESSIONS
Summary
This chapter covered the things that benefit from pattern matching: generics and regular expressions.
About generics, we learned that:- We can specify the kind of content that goes into a collection.
- Thanks to an improvement introduced in Java 7, we can use the diamond specifier
(<>) to shorten our code a bit, so long as the compiler can determine the type from
earlier in the line. - Generics can have multiple parameters.
- We can nest generic parameters to ensure we get the proper kinds of objects at
any depth. - We can use wildcards within generic parameters, to accommodate similar objects
(any object that extends a particular class or implements a particular set of
interfaces or both). - Generics let us catch problems at coding time rather than at run time, saving time
and embarrassment.
About regular expressions, we learned:- How to instantiate the member classes (Matcher and Pattern) of the
java.util.regex package. - What each of the metacharacters does.
- How to combine the metacharacters in a number of useful ways.
- How to make a pattern be reluctant (match the fewest possible characters) rather
than greedy (match the most possible characters). - That regular expressions can become very complex and a bit about how to
manage that complexity.
This chapter covered two language features that I hope you will find useful as you develop your own
programs. I especially hope that you'll use generics any time you use a collection, as you should embrace
best practices whenever you can. As for regular expressions, remember that they are supposed to make
things simpler. If you find that a regular expression is too hard to figure out, break it up with other String
operations and use multiple regular expressions rather than one big one.