Book Image

Java 9 Regular Expressions

By : Anubhava Srivastava
Book Image

Java 9 Regular Expressions

By: Anubhava Srivastava

Overview of this book

Regular expressions are a powerful tool in the programmer's toolbox and allow pattern matching. They are also used for manipulating text and data. This book will provide you with the know-how (and practical examples) to solve real-world problems using regex in Java. You will begin by discovering what regular expressions are and how they work with Java. This easy-to-follow guide is a great place from which to familiarize yourself with the core concepts of regular expressions and to master its implementation with the features of Java 9. You will learn how to match, extract, and transform text by matching specific words, characters, and patterns. You will learn when and where to apply the methods for finding patterns in digits, letters, Unicode characters, and string literals. Going forward, you will learn to use zero-length assertions and lookarounds, parsing the source code, and processing the log files. Finally, you will master tips, tricks, and best practices in regex with Java.
Table of Contents (15 chapters)
Title page
About the Author
About the Reviewer
Customer Feedback
Free Chapter
Getting Started with Regular Expressions

The Pattern class

The Pattern class represents the compiled form of a string regular expression. So far, we have provided all the regular expressions as strings. Each String regular expression must be compiled into an instance of the Pattern class before the Java regex engine can execute it. An instance of the Pattern class is used to create a Matcher object to match input text against the regular expression.

Let's list down the important and useful methods from the Pattern class first:

Method Signature


Static Pattern compile(String regex)

Compiles the given String regular expression into a Pattern instance.

Static Pattern compile(String regex, int flags)

Compiles the given String regular expression into a Pattern instance with the given flags. Flags can be one or more of DOTALL, MULTILINE, CASE_SENSITIVE, UNICODE_CHARACTER_CLASS and a few others. Check the Java Pattern API at for all flags and their descriptions...