用于验证名称的正则表达式

Question

I'm trying to create a regex that satisfies the following:

• The length of the name should be between 2 and 30 characters (both inclusive)
• The name can contain only alphabets and spaces
• The first character of each word of the name should be an upper case alphabet
• Each word should be separated by a space
• The name should not start or end with a space
• Special characters should not be allowed

Here's what I got so far:

^[A-Z][a-zA-z ]{1,29}$

If I put a [^ ] at the end, it allows a special character.

Answer 1

You can use

^[A-Z](?=.{1,29}$)[A-Za-z]*(?:\h+[A-Z][A-Za-z]*)*$

The pattern matches:

• ^ Start of string
• [AZ] Match an uppercase char AZ
• (?=.{1,29}$) Assert 1-29 chars to the right till the end of the string
• [A-Za-z]* Optionally match a char A-Za-z
• (?:\h+[AZ][A-Za-z]*)* Optionally repeat 1+ horizontal whitespace chars followed by again an uppercase char AZ and optional chars A-Za-z
• $ End of string

Regex demo

In Java with the doubled backslashes

String regex = "^[A-Z](?=.{1,29}$)[A-Za-z]*(?:\\h+[A-Z][A-Za-z]*)*$";

Answer 2

    var pattern = Pattern.compile("^((?=.{1,29}$)[A-Z]\\w*(\\s[A-Z]\\w*)*)$");
    var matcher = pattern.matcher("Multiple Words With One Space Separator");
    System.out.println(matcher.matches()); // false
    matcher = pattern.matcher("Multiple Words");
    System.out.println(matcher.matches());  // true

Answer 3

String regex = "[A-Z](?=.{1,29}$)[A-Za-z]{1,}([ ][A-Z][A-Za-z]{1,})*";