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Thread: Out of bounds error, 2d irregular array of integers

  1. #1
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    Default Out of bounds error, 2d irregular array of integers

    Hello,

    The code initializes a irregular array of integers, prints the length of each row in the array. Then I attempted to print the table[i][j], but I run into an out of bounds exception. In the for loops, the conditional statements are based on the value of table.length, which changes depending upon the row your looking at. I believe this has to do with the out of bounds exception.

    Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3. at hslengthdemoarray2.HSLengthDemoArray2.main(HSLengt hDemoArray2.java:32)
    Line 32 is: System.out.print(table[i][j] + " ");
    Output: 2d table array: 1 2 3

    The program should output the following:
    2d table array: 1 2 3 4 5 6 7 8 9
    2d table array with the one value changed: 1 66 3 4 5 6 7 8 9

    When I turn this into a regular 2d array, where each row has 3 elements, the code runs fine and output is as expected. I think this is because the nested for loop only acknowledges one value of table.length for all of i and j. For example; I thought when i = 0, table[0].length would be 3, in j loop, table.length = 3 based on the i loop. Then, when i = 1, table[1].length = 2, in j loop, table.length = 2 based on the i loop.. On the third step of the outerloop, when i = 2, table[2].length = 4, in j loop, table.length = 3 based on i loop. This appears not to be the case. It appears that table.length either holds a value based on i throughout both for loops or table.length changes based on i and j. It would be good if it only depended on i, I think.
    package hslengthdemoarray2;
     
    public class HSLengthDemoArray2 {
        public static void main(String[] args) {
            int[][] table = {
                {1,2,3},
                {4,5},
                {6,7,8,9},
            }; // A variable length table.
     
            // Print the length of each row within the array.
            System.out.println("length of table[0] is " + table[0].length);
            System.out.println("length of table[1] is " + table[1].length);
            System.out.println("length of table[2] is " + table[2].length);
            System.out.println();
     
            System.out.print("2d table array: ");
            for(int i=0; i<table.length; i++) {
                for(int j=0; j<table.length; j++) {
                    System.out.print(table[i][j] + " ");
                }
            }
     
            table[0][1] = 66;
     
            System.out.print("2d table array with the one value changed: ");
            for(int i=0; i<table.length; i++) {
                for(int j=0; j<table.length; j++) {
                    System.out.print(table[i][j] + " ");
                }
            }
        }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Out of bounds error, 2d irregular array of integers

    the for loops, the conditional statements are based on the value of table.length
    Try table[i].length to get the length of the subarray you are working with

  3. #3
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    Default Re: Out of bounds error, 2d irregular array of integers

    Thank you for your help Norm. Everything works well now, however, I do have another question related to this site. I am unable to post my messages as solved. When I initially post my problems, I can select whether or not the problem is solved but at that time the problems are unsolved. Then when I go back to post a follow up message after a solution has been posted, like right now, there is no option that I can find that posts the message as "solved". Any thoughts would be greatly appreciated. The option must work for some because I see other problems listed as solved.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Out of bounds error, 2d irregular array of integers

    No idea and it's something I should know, but don't.

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