This Algorithm verifies credit card numbers

Luhn Algorithm.java

import java.util.InputMismatchException;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        long creditCardNo = 0;
        Scanner scan = new Scanner(System.in);
        do {
            try {
                System.out.println("Enter the credit card number you wish to verify");
                creditCardNo = scan.nextLong();
            } catch (InputMismatchException inMisEx) {
                System.out.println("Invalid Credit Card Number, it should be purely digits !");
                scan.nextLine();
                System.out.println("\n");
            }
        }
        while (creditCardNo <= 0);

        StringBuilder cardStr = new StringBuilder();
        StringBuilder halfEvenSum = new StringBuilder();

        cardStr.append(creditCardNo);
        cardStr.reverse();

        int sumOdd = 0;
        int sumEven = 0;
        for (int i = 0; i < cardStr.length(); i++) {
//            The odd digits
            if (i % 2 == 0) {
                int sumOddi = Character.digit(cardStr.charAt(i), 10);
                sumOdd = sumOdd + sumOddi;
            }
//            The even digits
            else {
                int sumEveni = (Character.digit(cardStr.charAt(i), 10)) * 2;
                halfEvenSum.append(sumEveni);
            }
        }
        for (int j = 0; j < halfEvenSum.length(); j++) {
            int sumEvenj = Character.digit(halfEvenSum.charAt(j), 10);
            sumEven = sumEven + sumEvenj;
        }

        if ((sumEven + sumOdd) % 10 == 0) {
            System.out.print("card number entered is a valid ");
            switch (String.valueOf(creditCardNo).substring(0, 2)) {
                case "34":
                case "37":
                    System.out.print("American Express Card");
                    break;
                case "51":
                case "52":
                case "53":
                case "54":
                case "55":
                    System.out.print("Master Card");
                    break;
                case "40":
                case "41":
                case "42":
                case "43":
                case "44":
                case "45":
                case "46":
                case "47":
                case "48":
                case "49":
                    System.out.print("Visa Card");
                    break;
                default:
                    System.out.print("Card");
                    break;
            }
        } else {
            System.out.println("Card doesnt match any existing card numbers");
        }
    }
}

Luhn Test

The Luhn algorithm or Luhn formula, also known as the "modulus 10" or "mod 10" algorithm, is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers, IMEI numbers, National Provider Identifier numbers in the US, Canadian Social Insurance Numbers, and Greek Social Security Numbers (ΑΜΚΑ). It was created by IBM scientist Hans Peter Luhn.
Reference = Wikipedia