How to match a string (?,?,?) in Java

Question

My input string is of the form: String input = "(?,?,?)";

I am not able to come up with a valid regex to identify such strings

I have tried with following regex:

String regex = "(\\?,*)"; 

Assertion fails with the above regex for input strings such as (?,?) or (?,?,?,?)

Answer 1

You could match (? and then repeat 1+ times ,? and match ).

If a single question mark is also valid, you could change the quantifier from + to *

\(\?(?:,\?)+\)

Explanation

• \(\? Match (?
• (?:,\?)+ Non capturing group, repeat 1+ times ,?
• \) Match )

In Java

final String regex = "\\(\\?(?:,\\?)+\\)";

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