Using a text editor, submit a file that contains a list of at least 10 six-digit account numbers. Read in each account number and display whether it is valid. An account number is valid only if the last digit is equal to the sum of the first five digits divided by 10. Write only valiu d account numbers in an output file, each on its own line. Save the application as ValidateCheckDigits.java.

import java.io.File; import java.io.FileNotFoundException; import java.io.PrintWriter; import java.util.Scanner;

public class ValidateCheckDigits { public static void main(String[] args) { Scanner fileScanner = null; PrintWriter fileWriter = null;

String inputFileName ="accountNumbers.txt"; String outputFileName ="validaccounts.txt";

try { fileScanner = new Scanner(new File(inputFileName)); fileWriter = new PrintWriter(new File(outputFileName)); while(fileScanner.hasNextLine()) { int account = Integer.parseInt(fileScanner.nextLine()); if(isValidAccount(account)) { fileWriter.println(account); } } } catch (FileNotFoundException e) { System.out.println("Exception opening file"); } fileScanner.close(); fileWriter.close(); } private static boolean isValidAccount(int account) { int lastDigit = account %10; int temp = account/10; int sum = 0; while(temp!=0) { sum += temp%10; temp = temp/10; } if(sum%10 == lastDigit) return true; else return false; } }

----jGRASP exec: java ValidateCheckDigits Exception opening file Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.io.PrintWriter.close()" because "fileWriter" is null at ValidateCheckDigits.main(ValidateCheckDigits.java:34)

----jGRASP wedge2: exit code for process is 1. ----jGRASP: operation complete. validaccounts.txt

223355

555555

123456

542153

124333

656545

876786

345365

769679

556455