Java regular expressions for specific name\value format

Question

I'm not familiar yet with java regular expressions. I want to validate a string that has the following format:

String INPUT = "[name1 value1];[name2 value2];[name3 value3];";

namei and valuei are Strings should contain any characters expect white-space.

I tried with this expression:

String REGEX = "([\\S*\\s\\S*];)*";

But if I call matches() I get always false even for a good String.

what's the best regular expression for it?

Answer 1

This does the trick:

(?:\[\w.*?\s\w.*?\];)*

If you want to only match three of these, replace the * at the end with {3} .

Explanation:

(?: : Start of non-capturing group
\\[ : Escapes the [ sign which is a meta-character in regex. This allows it to be used for matching.
\\w.*? : Lazily matches any word character [az][AZ][0-9]_ . Lazy matching means it attempts to match the character as few times possible, in this case meaning that when will stop matching once it finds the following \\s .
\\s : Matches one whitespace
\\] : See \\[
; : Matches one semicolon
) : End of non-capturing group
* : Matches any number of what is contained in the preceding non-capturing group.

Answer 2

You should escape square brackets. Also, if your aim is to match only three, replace * with {3}

(\[\\S*\\s\\S*\];){3}