How can I strip all non digits in a string except the first character?

Question

I have a string that I want to make sure that the format is always a + followed by digits.
The following would work:

String parsed = input         


        

Answer 1

What about just

(?!^)\D+

Java string:

"(?!^)\\D+"

Demo at regex101.com

• \D matches a character that is not a digit [^0-9]

• (?!^) using a negative lookahead to check, if it is not the initial character