I recently started to learn Java, and I was giving the following problem to solve. After working on the code for a few days and eliminating the errors, my program still doesnt work even though there is no visible errors. Please help me. I have to turn this in pretty soon and I have tried everything but i cannot figure out what is the problem.

Task:

Credit card numbers follow certain pattern. A credit card number must be 16 digits, and must start with

• 4 for Visa cards

• 5 for Master cards

• 37 for American Express cards

• 6 for Discover cards

Suppose that you were asked to write down a Java program that validates the credit card number (if it is correct or not!). Here are the rules that determine the correctness of credit card number:

Suppose the credit card number = 4388576018402625

1) Double every digit in the even places from right to left. If doubling of a digit results in a two-digit number, add up the two digits to get a single digit number:

2*2 = 4

2*2 = 4

4*2 = 8

1*2 = 2

6*2 = 12 (1 + 2) = 3

5*2 = 10 (1 + 0) = 1

8*2 = 16 (1 +6) = 7

4*2 = 8

2) Now add all single-digit number from step 1 (4+4+8+2+3+1+7+8 = 37)

3) Add all digits in the odd places from right to left in the card number:

5+6+0+8+0+7+8+3 = 37

4) Sum the results from step 2 and 3

37 + 37 = 74

5) If the result in step 4 is divisible by 10, then credit card is valid, else it is not valid.

74 is not divisible by 10, so it is not valid!

Write a java program to accept a credit card number from keyboard as long, and then prints on screen, if it is valid or not. You should use the following:

public static int[] fillArray(long) : this method fills the credit card number in an array

public static int getSum(int[]) :calculated the summation from step 1 and 2

Public static int getOddSum(int[]): calculates the summation from step 3

Public static boolean isValid(int, int): determines if valid or not according to step 5.

Here is my code:

import java.util.Scanner; public class Taskone { // Main method public static void main(String[] args) { // Scanner creation Scanner input = new Scanner(System.in); // User input and array size System.out.println("\n\nEnter the number of your credit card: "); long card_number= input.nextLong(); int size= 16; // Array creation long[] array = new long[size]; // Storing card number as array for (int i = 0; i < array.length; i++) { System.out.println("\n"+i); long temp = card_number; while(temp !=0) { int temp_one = (int)temp%10; array[i] = temp_one; temp=temp/10; } System.out.println(array[i]); } /* String output = "The salaries entered are: "; for (int i = 0; i < array.length; i++) { output += array[i] + " "; } System.out.println(output); */ if (array[15] == 4) { System.out.println("\nYour credit card is a Visa Card."); } else if (array[15] == 5) { System.out.println("\nYour credit card is a Master Card."); } else if (array[15] == 3 && array[14] == 7) { System.out.println("\nYour credit card is an American Express Card."); } else if (array[15] == 6) { System.out.println("\nYour credit card is a Discover Card."); } else { System.out.println("\nYour credit card is invalid."); } // Step One long sum_even = 0; for (int i = 0; i < array.length; i=i+2) { long temp_store = array[i]; long double_value = temp_store * 2; if (double_value/10 == 0 ) { sum_even = sum_even + double_value; } else { long sum_internal = 0; while(double_value/10 != 0) { long temp_two = double_value%10; sum_internal = sum_internal + temp_two; } sum_even = sum_even + sum_internal; } } // Step Two long sum_odd = 0; for (int i = 0; i < array.length; i=i+2) { long temp_store_one = array[i]; sum_odd = sum_odd + temp_store_one; } // Validation long sum_total = sum_odd + sum_even; if (sum_total%10 == 0) { System.out.println("\nYour credit card is valid."); } else { System.out.println("\nYour credit card is invalid."); } } }

I would really appriciate any help. I used to work on note pad but now im using Eclipse.