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Thread: Help with array code.

  1. #1
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    Default Help with array code.

    Very new to Java and am trying to create an array that has 5 integers and display them from first to last and last to first. What I have so far:

    public class arrayex {
     
     
    	public static void main (String[]args)
    	{
    	//create an array to hold 5 integers
       	int [] array = new int [5];
        int i=0;
    	for(i=0;i<5;i++);
    	System.out.println (array[i]);
        }
     
    }

    Here is the error message I am getting. not sure why.
    Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 5
    at arrayex.main(arrayex.java:19)


  2. #2
    Administrator copeg's Avatar
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    Default Re: Help with array code.

    Check the semicolon after the loop...this will cause your loop to run, and only after completion the println will try to print...at which point i is equal to 5.

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    beginnerjava (July 1st, 2011)

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    Default Re: Help with array code.

    1. You have declared an array that can hold 5 int values, but you haven't put any int values into it...
    2. Your 'for' loop has a misplaced semi-colon at the end of the 'for...' statement, so the loop does nothing and the print of the array item happens after the loop has finished - when index i is 5, which is past the end of the array.

    ETA: D'oh! copeg got there first...

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    beginnerjava (July 1st, 2011)

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    Default Re: Help with array code.

    Fixed the semicolon and added the int values.

    [CODE] public static void main (String[]args)
    {
    //create an array to hold 5 integers
    int [] array = new int [5];

    int i=0;
    array[i] = i + 1;
    for(i=0;i<5;i++)

    System.out.println (array[i]);
    }

    }[CODE]

    Now, I get this output with only the number 1 and the rest zeros.

    output:

    1
    0
    0
    0
    0

    Process completed.

  7. #5
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    Default Re: Help with array code.

    Yes, that is what your code says to do: Put a value in element 0 of the array.
    int i=0;   // set the value of i to 0
    array[i] = i + 1;  // add 1 to i (1+0 = 1) and put that in element 0 of array
    What do you want your code to do?

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    Default Re: Help with array code.

    @ Norm, I want the code to display 5 integers from first to last then last to first.

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    Default Re: Help with array code.

    If you want your array to have 5 integers in it, you have to put 5 integers into it. The compiler can't read your mind. You've told it to put one integer into position 0, so it put one integer into position zero.

    I suggest you use one loop to put the integers into the array and a couple of loops to print them out again in first-to-last and last-to-first order.

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