I am having issues writing the code by using the binary code only, not the number its self. I need to be able to type in 1111 to get 15, and the code should only go from 3 to 8. When I dont type the binary code of 3 to 8, it should say "enter only binary number of 3 to 8"

I am having issues writing the code by using the binary code only, not the number its self.

I need to be able to type in 1111 to get 15, and the code should only go from 3 to 8. When I dont type the binary code of 3 to 8, it should say "enter only binary number of 3 to 8"

public static void main(String args[]) {
        String s;
        Scanner scan = new Scanner(System.in);
        while(true){
            System.out.println("Enter a binary number: ");
            s = scan.next();
             
            if(s.length()>=3 && s.length()<=8)
            {
            long result = 0;
                   
            for (int i = 0; i < s.length(); i++) {
            result = (long) (result + (s.charAt(i) - '0') * Math.pow(2, s.length()- i - 1));
            }
            System.out.println(result);
            break;  
            }
            else{
                System.out.println("Enter only binary number of 3 to 8 bits.\n");
            }
        }
        scan.close();
    }
}