It is possible to perform search and replace operations on strings in Java using regular expressions. A regular expression can be a single character, or a more complicated pattern. Thus by considering the above format the following Regular Expression can be applied to validate a String. The following example searches for data that is not all digits, which in our dataset is all but one record. Cookie length: 4 KB. Wildcards and regular expressions in URL Wildcards. "qwerty" or "asdf", with a sequence length of 4; does not apply to special characters). Let's see how can we capture this and display. In the aqString. To specify “not” in a regular expression, a caret (^) is used within the brackets to exclude the referenced characters. 10 vulnerabilities. ^4\d{15}$