View difference between Paste ID: ZBBBSd8t and q88uHpZr

 import java.util.Scanner;
 
 /**
  * Input: One String with numbers. numbers are separated by a single space
  * Output: numbers recognized and their sum Allowed: isDigit() substring()
  * charAt() Integer.parseInt() length() Forbidden: split(), arrays or
  * collections
  */
 public class NumberParser {
 
     public static void main(String[] args) {
         // print out the welcome header that gives the user instructions:
         System.out.println("Welcome to the Number Parser! Please enter one line"
                 + " of numbers, separated by a single space between each,"
                 + " followed by a return.");
 
         // get the user input
         Scanner stdin = new Scanner(System.in);
         String line = stdin.nextLine();
 
-        // make sure the user input isn't empty or null
+        // make sure the user input isn't null
         if (line == null) {
             System.out.println("Invalid input. Input was null");
             System.exit(0);
         }
 
 	// make sure there's a non-digit character at the end for easier parsing later
 	line = line + " ";
 
         /*
          * Now we have a valid input, and can parse out the numbers
          */
 
         // set up variables that will keep track of things as we go
         int sum = 0;
         int beginIndex = 0;
 
         // step through the input String one character at a time.
         for (int currentIndex = 0; currentIndex < line.length(); ++currentIndex) {
             // get the character at the current index
             char currentChar = line.charAt(currentIndex);
 
             // if the character is NOT a digit, then we have reached the end of a number.
             if (!Character.isDigit(currentChar)) {
 
                 // make sure the number substring has at least one character in it
                 if (currentIndex - beginIndex > 0) {
 
                     // pull out the number substring.
                     String numberSubstring = line.substring(beginIndex, currentIndex);
 
                     // convert that number substring into an integer
                     int currentNumber = Integer.parseInt(numberSubstring);
 
                     // print out the number
                     System.out.print(currentNumber + ", ");
 
                     // add the number to the running total
                     sum = sum + currentNumber;
                 }
 
                 // we're on a non-digit character, so a new number substring might begin next character
                 beginIndex = currentIndex + 1;
             }
         }
 
         // print out the sum
         if (sum > 0) {
             System.out.println("sum: " + sum);
         } else {
             System.out.println("No numbers present.");
         }
     }
 }