Problem with exceptions and arrays

Question

Can't really understand what's going wrong here?

It's just a simple exception with an array out of bounds.

public class Days
{
    public static void main (String args[])
    {
        String[] dayArray = new String [4];
        {
            dayArray [0] = "monday";
            dayArray [1] = "tuesday";
            dayArray [2] = "wednesday";
            dayArray [3] = "Thursday";
            dayArray [4] = "Friday";

            try
            {
                System.out.println("The day is " + dayArray[5]);
            }
            catch(ArrayIndexOutOfBoundsException Q)
            {
                System.out.println(" invalid");
                Q.getStackTrace();
            }
            System.out.println("End Of Program");
        }
    }
}

Does anybody have any ideas as too why this won't run? I'm getting the error:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
    at Days.main(Days.java:14)

It is straightforward you declare array with 5 element and you use 6'th element that not exist and out of bound — Sajad Bahmani
– Sajad Bahmani, Commented Nov 18, 2009 at 13:50

guerda · Accepted Answer · 2009-11-19 07:18:03Z

7

You should declare it as capable of 5 items, not 4, in its declaration.

new String [5];

edited Nov 19, 2009 at 7:18

guerda

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answered Nov 18, 2009 at 13:41

David Hedlund

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2 Comments

BalusC Over a year ago

Exactly. For convenience, here's the Arrays Tutorial: java.sun.com/docs/books/tutorial/java/nutsandbolts/arrays.html

ziftech Over a year ago

and 5th element is dayArray[4]

guerda · Accepted Answer · 2009-11-18 13:42:22Z

2

Array are limited on creation. In your example, it has a size of 4 fields.
With a 0-indexed array it means you can access these fields, not any more:

dayArray [0] = "monday";
dayArray [1] = "tuesday";
dayArray [2] = "wednesday";
dayArray [3] = "Thursday";

answered Nov 18, 2009 at 13:42

guerda

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1 Comment

OVERTONE Over a year ago

ah so my array was too small. i wanst aware of that.

Ken · Accepted Answer · 2009-11-18 13:55:14Z

2

When appropriate, let the compiler do the counting for you:

String[] dayArray = {
  "Monday",
  "Tuesday",
  "Wednesday",
  "Thursday",
  "Friday",
};

This way, you can add or remove elements without having to change the array length in another place. Less typing, too.

answered Nov 18, 2009 at 13:55

Ken

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Comments

Soufiane Hassou · Accepted Answer · 2009-11-18 13:42:04Z

0

You array has a size of 4, and you are adding 5 elements.

answered Nov 18, 2009 at 13:42

Soufiane Hassou

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Comments

mwalling · Accepted Answer · 2009-11-18 13:42:07Z

0

You're defining five elements for a four element array. Java uses zero based indexes.

answered Nov 18, 2009 at 13:42

mwalling

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