How to form array in do while loop with input validation?

Question

public class Array {

  public static void main ( String[] args ) {


    int DAYS_SIZE = 5;
    double[] sales = new double[DAYS_SIZE];

    String input;
    char userResponse;
    Scanner keyboard = new Scanner(System.in);

    double total = 0;
    double average = 0;
    int index = 0;

    do {
        index++;
        System.out.print("Enter sales for day " + index  + ": ");
        sales[index] = keyboard.nextInt();             

        System.out.print("Another ( y or n )? " );
        input = keyboard.next();
        userResponse = input.charAt(0);

     } while ( userResponse == 'Y' || userResponse == 'y');   

  }
}

I keep getting java.lang.ArrayIndexOutOfBoundsException: 5 at the last day

I know why this is happening but i dont know how to solve it

Emerson Cod · Accepted Answer · 2015-11-10 21:41:49Z

1

you increase your index before you access the array without checking whether the index is already bigger than the size of the array. When the user enters days and days index will become bigger than 5 in your case.

Also as the index starts with 0 and not with 1, there is no index 5, but only 0-4

answered Nov 10, 2015 at 21:41

Emerson Cod

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4 Comments

nate opas Over a year ago

Should i add a decision structure that checks whether if the index is bigger than the size of the array, or is there a better way?

mohammedkhan Over a year ago

Why do you need to increment index straight away? Just move it to the bottom of your iteration.

nate opas Over a year ago

i put it at the bottom and i still get java.lang.ArrayIndexOutOfBoundsException: when i input the sales for the last day which would be 5.

Emerson Cod Over a year ago

because you never check whether the index is bigger than the size of the array. You can either add the index < sales.length check in your while condition or separately if you like to give the user an extra message like "no more days left" or so

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