How to generate OTP Number with 6 digits

Question

What is an OTP number in a login authentication system? Is there any specific algorithm for generating OTP numbers using java (android). Or is an OTP something like random n

Answer 1

public static void main(String []args){
            java.util.Random r=new java.util.Random();
            int otp = r.nextInt(1000000); // no. of zeros depends on the OTP digit
            System.out.println(otp);
}