# Package java.util.regex

package java.util.regex
Classes for matching character sequences against patterns specified by regular expressions.

An instance of the `Pattern` class represents a regular expression that is specified in string form in a syntax similar to that used by Perl.

Instances of the `Matcher` class are used to match character sequences against a given pattern. Input is provided to matchers via the `CharSequence` interface in order to support matching against characters from a wide variety of input sources.

Unless otherwise noted, passing a `null` argument to a method in any class or interface in this package will cause a `NullPointerException` to be thrown.

## Related Documentation

An excellent tutorial and overview of regular expressions is Mastering Regular Expressions, Jeffrey E. F. Friedl, O'Reilly and Associates, 1997.

Since:
  1.4

Related Packages
Package
Description
java.util
Contains the collections framework, some internationalization support classes, a service loader, properties, random number generation, string parsing and scanning classes, base64 encoding and decoding, a bit array, and several miscellaneous utility classes.
Class
Description
Matcher
An engine that performs match operations on a character sequence by interpreting a `Pattern`.
MatchResult
The result of a match operation.
Pattern
A compiled representation of a regular expression.
PatternSyntaxException
Unchecked exception thrown to indicate a syntax error in a regular-expression pattern.