I am working on a credit card validation program and so far I got my input workign to where it will read possible valid numbers from a file and sort them in to two array lists - one possible numbers and the second one numbers already deemed to be invalid based off the length of the number. The code for that part is below - including just a simple output method to keep track of seeing if my arraylist is working. I need help figuring out how to pass the possibleNumber array list to a Luhn formula class to compleatly validate the number. I am also going to have a class that extends the Luhn Formula class to also check what kind of card the validated number is based off the length and the first numbers of the card.

import java.io.IOException; import java.io.*; import java.util.*; import java.util.Scanner; import java.util.ArrayList; import java.io.File;

public class LuhnFormulaDemo { public static void main(String[] args) throws FileNotFoundException { String creditNumberString ; //String line = null; int posNumCount = 0; int invalNumCount= 0; ArrayList invalidNumber = new ArrayList(); ArrayList possibleNumber = new ArrayList(); //create new scanner object for keyboard inpit Scanner keyboard = new Scanner(System.in); //get the file name System.out.println("Please input the file name with the credit card number: "); String fileName = keyboard.nextLine(); //Open the file and create a new file scanner. File file = new File(fileName); //create a scanner object to read the file/ will throw an exception if file not found Scanner inputFile = new Scanner(file); //if file found System.out.println("Thankyou, your file was found"); while(inputFile ==null) { System.out.println("The file " + fileName + " does not exist."); System.out.println("Please enter another file name: "); fileName = keyboard.nextLine();

} while (inputFile.hasNext()) { //get the poissible credit number from the file creditNumberString = inputFile.nextLine(); //find the length of the number int length = creditNumberString.length(); if (length >= 15 && length <= 19) { long creditNumberLong = Long.parseLong(creditNumberString); possibleNumber.add(creditNumberLong); posNumCount ++; } else { long creditNumberLong = Long.parseLong(creditNumberString); invalidNumber.add(creditNumberLong); invalNumCount ++; } } System.out.println("Invalind num count tests: " + invalNumCount); System.out.println("Possible valid num count tests: " + posNumCount); for(int index1 = 0; index1 < possibleNumber.size(); index1++) { System.out.println("Index # for possible: " + index1 + " Possible Credit Number: " + possibleNumber.get(index1)); } for(int index2 = 0; index2 < invalidNumber.size(); index2++) { System.out.println("Index # for invalid: " + index2 + " Invalid Credit Number: " + invalidNumber.get(index2)); } } }

Here is the basis I have at the moment for my Luhn formula import java.io.IOException; import java.io.*; import java.util.*; import java.util.Scanner; import java.util.ArrayList; import java.io.File; public class LuhnFormula { public static void Luhn() { } public ArrayList getPossibleNumbers() { } public static boolean CheckNumber(String creditNumber) { int sum = 0; boolean alternate = false; for (int i = creditNumber.length() - 1; i >= 0; i--) { int n = Integer.parseInt(creditNumber.substring(i, i + 1)); if (alternate) { n *= 2; if (n > 9) { n = (n % 10) + 1; } } sum += n; alternate = !alternate; } return (sum % 10 == 0); } }

Here are some numbers in the file im using in the first step of the validation in my main (demo) class.

3158539628375348

3337465828248404

3112804683572030

3112804683572033

5435528978467581

6706465468107999

6304362971054667

6706169762827894

6706169762827892

4844104341377697

4913405490886727

4844885754351829

4844885754351822

6371473570875275

6381475006869978

6389057917814806

347100734345549

347100734345543

6011162533805000

6011621663574413