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

protected void onCreate(Bundle savedInstanceState)
 {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Random otp  =new Random();

        StringBuilder builder=new StringBuilder();
        for(int count=0; count<=10;count++) {
            builder.append(otp.nextInt(10));
        }
        Log.d("Number", " " + builder.toString());

        TextView txt = (TextView) findViewById(R.id.txt);

        txt.setText(builder.toString());
   }