POSIX character classes and Java character classes : Introduction « Regular Expressions « Java Tutorial

Character Class Meta-CharacterMatches
\p{Lower}Lowercase letter [a-z]
\p{Upper}Uppercase letter [A-Z]
\p{ASCII}All ASCII [\x00-\x7F]
\p{Alpha}Any lowercase or uppercase letter
\p{Digit}A digit [0–9]
\p{Alnum}Any letter or digit
\p{Punct}Punctuation [!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~]
\p{Graph}A visible character: any letter, digit, or punctuation
\p{Print}A printable character; same as \p{Graph}
\p{Blank}A space or tab [ \t]
\p{Cntrl}A control character [\x00-\x1F\x7F]
\p{XDigit}Hexadecimal digit [0–9a–fA–F]
\p{Space}A whitespace character [ \t\n\x0B\f\r]

8.1.1.Meta-characters predefined to match specific characters.
8.1.2.Meta-characters to match against certain string boundaries.
8.1.3.Regular expression languages also have character classes.
8.1.4.POSIX character classes and Java character classes
8.1.5.Java Character Class
8.1.6.Match a particular character a specified number of times.
8.1.7.Read regular expression from console
8.1.8.Regex Test Harness
8.1.9.Match Java source file and file and class name
8.1.10.Finding all words that start with an 'a'
8.1.11.Simple validation using the Pattern and Matcher objects
8.1.12.A possessive qualifier
8.1.13.Find the starting point of the second 'Bond'
8.1.14.A negative look ahead
8.1.15.A negative behind ahead
8.1.16.A positive look ahead
8.1.17.Pattern helper
8.1.18.Escapes characters that have special meaning to regular expressions