Set minimum and maximum characters in a regular expression

by

Yes

Just like + means one or more you can use {3,30} to match between 3 and 30

For example [a-z]{3,30} matches between 3 and 30 lowercase alphabet letters

From the documentation of the Pattern class

X{n,m}    X, at least n but not more than m times

In your case, matching 3-30 letters followed by spaces could be accomplished with:

([a-zA-Z]\s){3,30}

If you require trailing whitespace, if you don’t you can use: (2-29 times letter+space, then letter)

([a-zA-Z]\s){2,29}[a-zA-Z]

If you’d like whitespaces to count as characters you need to divide that number by 2 to get

([a-zA-Z]\s){1,14}[a-zA-Z]

You can add \s? to that last one if the trailing whitespace is optional. These were all tested on RegexPlanet

If you’d like the entire string altogether to be between 3 and 30 characters you can use lookaheads adding (?=^.{3,30}$) at the beginning of the RegExp and removing the other size limitations

All that said, in all honestly I’d probably just test the String‘s .length property. It’s more readable.

More Related Contents:

  1. Java Variable Substitution
  2. Java regular expression “( *|)”: what does the pipe do? [duplicate]
  3. Want to extract values from text file using regex
  4. Java regex email
  5. How to split a string between letters and digits (or between digits and letters)?
  6. How to split a string, but also keep the delimiters?
  7. How can non-ASCII characters be removed from a string?
  8. Regex look-behind without obvious maximum length in Java
  9. Returning overlapping regular expressions
  10. A regex to match a substring that isn’t followed by a certain other substring
  11. Java; String replace (using regular expressions)?
  12. Java regular expressions and dollar sign
  13. Java doesn’t work with regex \s, says: invalid escape sequence
  14. Cancelling a long running regex match?
  15. Why String.replaceAll() in java requires 4 slashes “\\\\” in regex to actually replace “\”?
  16. How to filter string for unwanted characters using regex?
  17. Split a string, at every nth position
  18. How to find the exact word using a regex in Java?
  19. Regular Expression to Match String Exactly?
  20. How can I find repeated characters with a regex in Java?
  21. Pattern to extract text between parenthesis
  22. What are the differences between perl and java regex capabilities?
  23. Java Regex Illegal Escape Character in Character Class
  24. Regex search with pattern containing (?:.|\s)*? takes increasingly long time
  25. Regular Expression for matching parentheses
  26. Java Regex – Using String’s replaceAll method to replace newlines
  27. Regex to remove spaces between numbers only
  28. Regex Pattern Catastrophic backtracking
  29. Print regex matches in java
  30. regex replace all ignore case

Leave a Comment