Regex

import java.util.regex.*;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String fullName = "";
        String gender = "";
        int age = 0; //done
        String dob = "";
        String cnic = "";
        String email = "";
        String address = "";
        String cellPhone = "";
        String landLine = "";
        String username = "";
        String password = "";


        System.out.println("FullName (SPECIAL CHARACTERS AND NUMBERS ARE NOT ALLOWED, ONLY SALUTATIONS ARE!)");
        fullName = input.nextLine();
        while(!regexChecker("^[A-Za-z\\s]{1,}[\\.]{0,1}[A-Za-z\\s]{0,}$", fullName)){
            System.out.println("Invalid Format, please renter your FullName with the proper format");
            fullName = input.nextLine();
        }

        System.out.println("Gender (MALE / FEMALE / M / F)");
        gender = input.nextLine();
        while(!regexChecker("^M|MALE|F|FEMALE$", gender)){
            System.out.println("Invalid Gender, please renter your Gender with the proper Format!");
            gender = input.nextLine();
        }

        System.out.println("Age (YOU MUST BE OLDER THAN 18 YEARS)");
        age = input.nextInt();
        if(age < 18){
            System.out.println("Below 18 are not allowed to enter, terminating program!");
            System.exit(0);
        }

        System.out.println("Date of Birth (DD/MM/YYY)");
        dob = input.nextLine();
        while(!regexChecker("^(0?[1-9]|[12][0-9]|3[01])/(0?[1-9]|1[012])/((19|20)\\d\\d)$", dob)){
            System.out.println("Invalid Format/Date, please renter your DOB with the proper format");
            dob = input.nextLine();
        }

        System.out.println("CNIC number");
        cnic = input.nextLine();
        while(!regexChecker("^([0-9]{6})( |-)?([0-9]{6})( |-)?([0-9]{1})$", cnic)){
            System.out.println("Invalid CNIC, please renter your CNIC with the proper format");
            cnic = input.nextLine();
        }

        System.out.println("Email Address");
        email = input.nextLine();
        while(!regexChecker("^[A-Za-z0-9._%-]+@[A-Za-z0-9]+\\.[A-Za-z]{2,4}$", email)){
            System.out.println("Invalid Format, please renter your Email with the proper format");
            email = input.nextLine();
        }

        System.out.println("Address");
        address = input.nextLine();
        while(!regexChecker("^(.){0,50}$", address)){
            System.out.println("Your address should not be longer than 50 characters");
            address = input.nextLine();
        }

        System.out.println("Cellphone number");
        cellPhone = input.nextLine();
        while(!regexChecker("^(((00|\\+)?(923))[0-9]{9})|((03)[0-9]{9})$", cellPhone)){
            System.out.println("Invalid number, please renter your number with the proper Format!");
            cellPhone = input.nextLine();
        }

        System.out.println("Landline number (STARTS WITH 021 OR 3)");
        landLine = input.nextLine();
        while(!regexChecker("^((021)( |-)?)?(3)[0-9]{7}$", landLine)){
            System.out.println("Invalid number, please renter your number with the proper Format!");
            landLine = input.nextLine();
        }

        System.out.println("Username");
        username = input.nextLine();
        while(!regexChecker("^(.){0,6}$", username)) {
            System.out.println("Your username should not be longer than 6 characters");
            username = input.nextLine();
        }

        System.out.println("Password (ATLEAST 1 LETTER IN CAPITAL, ATLEAST 1 NUMBER, ATLEAST LETTER IN SMALL");
        password = input.nextLine();
        while (!regexChecker("^(?=.*[a-z])(?=.*[A-Z])(?=.*\\d)[a-zA-Z\\d]{8,}$", password)) {
            System.out.println("Invalid");
            password = input.nextLine();
        }
        System.out.println("Full Name" + fullName);
        System.out.println("Gender" +  gender);
        System.out.println("Age" + age);
        System.out.println("Date of Birth" + dob);
        System.out.println("CNIC" + cnic);
        System.out.println("Email" + email);
        System.out.println("Address" + address);
        System.out.println("Cell Phone" + cellPhone);
        System.out.println("Landline" + landLine);
        System.out.println("Username" + username);
        System.out.println("Password" + password);
    }

    public static boolean regexChecker(String theRegex, String str2Check) {
        Pattern checkRegex = Pattern.compile(theRegex);
        Matcher regexMatcher = checkRegex.matcher(str2Check);
        return regexMatcher.find();

    }
}