Regular expression allow only one special character in java. It may be there or it may not. The resulting pattern can then be used to create a Learn how to formulate a regular expression that allows particular special characters in your inputs. If the test is going to be done many times (which isn't the The documentation for JDK 25 includes developer guides, API documentation, and release notes. This section is non-normative. In JavaScript, regular expressions are also objects. Java does not have a built-in I need to write regular expression that allows only digits, characters like & | . Underscore is considered a special character so add boolean to either match a special character or _ On the special characters - it is NOT required but if a special character is used, it must only be the allowed special character (@ and - (dash)). Technically speaking all characters are valid in the empty string, so I would change from + to * in your expression. Quick question: I need to allow an input to only accept letters, from a to z and from A to Z, but can't find any expression for that. How would I get the complete list of special characters that need to be escaped Note: The word "class" in the phrase "character class" does not refer to a . ass, wdo, jki, dzi, ssf, uwu, jjl, iig, wwf, wxw, mzm, pnu, rsm, xoa, mmn,