As we have seen from the preceding examples, certain character classes, such as digits [0-9] or word characters [0-9A-Za-z_], are used in most regex patterns. The Java language, like all regular expression flavors, provides convenient predefined character classes for these character classes. Here is the list:
| Shorthand Class | Meaning | Character Class |
| \d | A digit 0-9 | [0-9] |
| \D | A non-digit | [^\d] |
| \w | A word character | [a-zA-Z0-9_] |
| W | A non-word character | [^\w] |
| \s | A whitespace character, including line break | [ \t\r\n\f\x0B] |
| \S | A non-whitespace chacracter | [^\s] |
| \h | A horizontal whitespace character | [ \t\xA0\u1680\u180e\u2000-\u200a\u202f\u205f\u3000] |
| \H | A non-horizontal whitespace character | [^\h] ... |
