Integer.parseInt throws format exception, what to do?

[Justin_]

I'm getting a numberFormatExcetion from this code that reads integers from a textfile. The textfile has a new integer on each line, so if you made a textfile for example like this:

code:

1 2 3

That would be what you need to run the program and call it IntegerData.txt.

Here's the exact error:

code:

Exception in thread "main" java.lang.NumberFormatException: null         at java.lang.Integer.parseInt(Integer.java:415)         at java.lang.Integer.parseInt(Integer.java:497)         at Sort.sortIt(MooserBubbleSort.java:31)         at MooserBubbleSort.main(MooserBubbleSort.java:9)

Java:

import java.io.*; import java.util.*; public class MooserBubbleSort {         public static void main(String args[]) throws IOException         {                 Sort integerTextFile = new Sort();                 integerTextFile.sortIt();         } } class Sort {         private int lengthOfArray = 10;     private int[] numberArray = new int[lengthOfArray];     private int index = 0;     public void sortIt() throws IOException     {         String inputFile = "IntegerData.txt";         String stringNumber;         BufferedReader input;         int number;         input = new BufferedReader(new FileReader(inputFile));         do         {             stringNumber = input.readLine();             number = Integer.parseInt(stringNumber);             addNumberToArray(number);         }  while (stringNumber != null);         bubbleSort(numberArray, index - 1);         for (int i = 0; i <= lengthOfArray; i++)           System.out.println(numberArray[i]);     }     private void bubbleSort(int numbers[], int array_size)         {               int i, j, temp;               for (i = (array_size - 1); i >= 0; i--)               {             for (j = 1; j <= i; j++)             {             if (numbers[j-1] > numbers[j])             {               temp = numbers[j-1];               numbers[j-1] = numbers[j];               numbers[j] = temp;             }           }         }     }     private void addNumberToArray(int num)     {         if (lengthOfArray == index)         {             lengthOfArray = 2 * lengthOfArray;             int[] temp = new int[lengthOfArray];             for (int i = 0; i < index; i++)                         temp[i] = numberArray[i];             numberArray = temp;         }         numberArray[index] = num;         index++;     } }

[HellblazerX]

your gonna have to replace that do while loop with a while loop, because what your program is doing is reading 1 more line than what your file actually has.

so, on your line:

code:

do             {                     stringNumber = input.readLine();                     number = Integer.parseInt(stringNumber);                     addNumberToArray(number);               }  while (stringNumber != null);

replace that with this:

code:

stringNumber = input.readLine ();         while (stringNumber != null)         {             number = Integer.parseInt (stringNumber);             addNumberToArray (number);             stringNumber = input.readLine ();         }

also theres another problem i noticed with this line:

code:

for (int i = 0; i <= lengthOfArray; i++)

you shouldn't have have that <= sign, but rather just a < sign, otherwise you'll be calling on a non existing element. You have to remember that arrays start at 0, so an array with a size of 3 will go 0,1,2.

[Justin_]

Thanks Hellblazer