how to Validate a Phone number so that it should not allow all same numerics like 99999999999 or 11111111111 in java

Question

how to Validate a Phone number so that it should not allow all same numerics like 99999999999 or 11111111111 in JAVA

thanks Sunny Mate

Answer 1

If feasable, I'd try to discredit that requirement so it will be rejected.

No matter what you put into your plausibility checks, a user trying to avoid mandatory fields by entering junk into them will always succeed. You either end up having "smarter" harder-to-detect junk data items, or having a plausibility check which does not let all real-world data through into the system. Shit in, shit out. Build a shitshield, and your users will create fascies you never imagined.

There is no way to program around that (except for simple things that usually are unintended, erraneously entered typos and so on).

Answer 2

The following regex:

^(\d)(?!\1+$)\d{10}$

matches 11 digit strings that do not have all the same digits.

A demo:

public class Main {
    public static void main(String[] args) throws Exception {
        String[] tests = {
                "11111111111",
                "99999999999",
                "99999999998",
                "12345678900"
        };
        for(String t : tests) {
            System.out.println(t+" :: "+t.matches("(\\d)(?!\\1+$)\\d{10}"));
        }
    }
}

which produces:

11111111111 :: false
99999999999 :: false
99999999998 :: true
12345678900 :: true