Question

I want to write a regex where a string has
(9 characters) and start with either “g” or “r”
and then are all numbers afterward.

I have written this but it does not work:

public static void main(String[] args) {
    String id= "g57895452";
    String pattern = "/^g([0-9]+){8}$/";
    if (id.matches(pattern)) {
        System.out.println("true");
    } else {
        System.out.println("false");
    }
}

Answer 1

Corrected re:

"^[gr]([0-9]{8})$"

You need not + when you already has {8}.

Also you don’t need () when you don’t want to use the group further in the code.

"^[gr][0-9]{8}$"