Java in a Nutshell, 5th Edition

Name

Matcher

Synopsis

A Matcher objects encapsulate a regular expression and a string of text (a Pattern and a java.lang.CharSequence) and defines methods for matching the pattern to the text in several different ways, for obtaining details about pattern matches, and for doing search-and-replace operations on the text. Matcher has no public constructor. Obtain a Matcher by passing the character sequence to be matched to the matcher( ) method of the desired Pattern object. You can also reuse an existing Matcher object with a new character sequence (but the same Pattern) by passing a new CharSequence to the matcher’s reset( ) method. In Java 5.0, you can use a new Pattern object on the current character sequence with the usePattern( ) method.

Once you have created or reset a Matcher, there are three types of comparisons you can perform between the regular expression and the character sequence. All three comparisons operate on the current region of the character sequence. By default, this region is the entire sequence. In Java 5.0, however, you can set the bound of the region with region( ). The simplest type of comparison is the matches( ) method. It returns true if the pattern matches the complete region of the character sequence, and returns false otherwise. The lookingAt( ) method is similar: it returns true if the pattern matches the complete region, or if it matches some subsequence at the beginning of the region. If the pattern does not match the start of the region, lookingAt( ...