This class won't compile
I took a long break from learning Java and can't figure out what I'm missing in the code.
I'm trying to run a simple Luhn Algorithm to verify C.C.'s. Although anachronistic, I just wanted to start from somewhere.
Any assistance would be helpful. I'm using Netbeans 5.5.
publicabstractclass Luhn Algo{
privatestatic String getDigitsOnly (String s){
StringBuffer digitsOnly =new StringBuffer ();
char c;
for (int i = 0; i < s.length (); i++){
c = s.charAt (i);
if (Character.isDigit (c)){
digitsOnly.append (c);
}
}
return digitsOnly.toString ();
}
//-
// Perform Luhn check
//-
publicstaticboolean isValid (String cardNumber){
String digitsOnly = getDigitsOnly (cardNumber);
int sum = 0;
int digit = 0;
int addend = 0;
boolean timesTwo =false;
for (int i = digitsOnly.length () - 1; i >= 0; i--){
digit = Integer.parseInt (digitsOnly.substring (i, i + 1));
if (timesTwo){
addend = digit * 2;
if (addend > 9){
addend -= 9;
}
}
else{
addend = digit;
}
sum += addend;
timesTwo = !timesTwo;
}
int modulus = sum % 10;
return modulus == 0;
}
//--
// Test
//--
publicstaticvoid main (String[] args){
String cardNumber ="4408 0412 3456 7890";
boolean valid = LuhnCheck.isValid (cardNumber);
System.out.println (cardNumber +": " + valid);
cardNumber ="4408 0412 3456 7893";
valid = LuhnCheck.isValid (cardNumber);
System.out.println (cardNumber +": " + valid);
cardNumber ="4417 1234 5678 9112";
valid = LuhnCheck.isValid (cardNumber);
System.out.println (cardNumber +": " + valid);
cardNumber ="4417 1234 5678 9113";
valid = LuhnCheck.isValid (cardNumber);
System.out.println (cardNumber +": " + valid);
}
}
Am I missing some sort of import utility. I can't get to seem this program to run.
