Java regular expressions with java.util.regex

The java.util.regex package primarily consists of three classes: Pattern, Matcher, and PatternSyntaxException.

• A Pattern object is a compiled representation of a regular expression. The Pattern class provides no public constructors. To create a pattern, you must first invoke one of its public static compile methods, which will then return a Pattern object. These methods accept a regular expression as the first argument; the first few lessons of this trail will teach you the required syntax.
• A Matcher object is the engine that interprets the pattern and performs match operations against an input string. Like the Pattern class, Matcher defines no public constructors. You obtain a Matcher object by invoking the matcher method on a Pattern object.
• A PatternSyntaxException object is an unchecked exception that indicates a syntax error in a regular expression pattern.