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25 
26 /**
27  * Classes for matching character sequences against patterns specified
28  * by regular expressions.
29  *
30  * <p> An instance of the {@link java.util.regex.Pattern} class
31  * represents a regular expression that is specified in string form in
32  * a syntax similar to that used by Perl.
33  *
34  * <p> Instances of the {@link java.util.regex.Matcher} class are used
35  * to match character sequences against a given pattern.  Input is
36  * provided to matchers via the {@link java.lang.CharSequence}
37  * interface in order to support matching against characters from a
38  * wide variety of input sources. </p>
39  *
40  * <p> Unless otherwise noted, passing a {@code null} argument to a
41  * method in any class or interface in this package will cause a
42  * {@link java.lang.NullPointerException NullPointerException} to be
43  * thrown.
44  *
45  * <h2>Related Documentation</h2>
46  *
47  * <p> An excellent tutorial and overview of regular expressions is <a
48  * href="http://www.oreilly.com/catalog/regex/"><i>Mastering Regular
49  * Expressions</i>, Jeffrey E. F. Friedl, O'Reilly and Associates,
50  * 1997.</a> </p>
51  *
52  * @since 1.4
53  * @author Mike McCloskey
54  * @author Mark Reinhold
55  */
56 package java.util.regex;
57