Check

import java.util.Scanner;
public class Check {

    public static boolean checkUsername(String user){
        return checkLetterUser(user) && checkLengthUser(user) && checkDot(user);
    }

    public static boolean checkPassword(String pwd, String user){
        return checkLengthPwd(pwd) && checkSamePwd(pwd,user);
    }

    public static boolean checkLengthUser(String user) {
        int lenu = user.length();
        return (lenu > 4 && lenu < 225);
    }

    public static boolean checkLetterUser(String user) { //BUG : capital letter runs false
        String letter = "abcdefghijklmnopqrstuvwxyz";
        String space = " \\";
        String first = user.toLowerCase().substring(0,1);
        return (letter.indexOf(first) != -1) && (user.indexOf(space) == -1);
    }

    public static boolean checkDot(String user) {
        return user.indexOf("..") == -1;
    }

    public static boolean checkLengthPwd(String pwd) {
        int lenp = pwd.length();
        return (lenp > 4 && lenp < 225);
    }

    public static boolean checkSamePwd(String pwd, String user) {
        String small = user.toLowerCase();
        return (pwd.equals(small));
    }

    public static void main (String [] args) {
        Scanner sc = new Scanner (System.in);

        System.out.print("Username : ");
        String user = sc.nextLine();
        //String first = user.toLowerCase().substring(0,1);
        //System.out.println(first);
        String s1 = (checkUsername(user)) ? "Y" : "N";
        System.out.println(s1);
        System.out.print("Password : ");
        String pwd = sc.nextLine();
        String s2 = (checkPassword(pwd,user)) ? "Y" : "N";
        System.out.println(s2);
    }

}