CODEWITHSUNDEEP
javanetbeanside
Michael MacDonald
Michael MacDonald

Reputation: 433

Someone familiar with Netbeans: Why does this happen? Error isn't really an error?

When writing something simple like this: 

import java.util.Scanner;
public class Practice {  
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in); 
        System.out.println("Please enter array size: ");
        int x = sc.nextInt();
        int [] anArray;
        int index = 100;
        anArray = new int[x];
        for (int i=0; i<=x; i++){
            anArray[i] = index;
            index += 100;
            System.out.println ("Element at index "+ i + ": " + anArray[i]);
        }

    }

}

Netbeans compiles and runs the code properly but the output ends up looking like this:

run:
Please enter array size: 
12
Element at index 0: 100
Element at index 1: 200
Element at index 2: 300
Element at index 3: 400
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 12
Element at index 4: 500
Element at index 5: 600
Element at index 6: 700
Element at index 7: 800
Element at index 8: 900
Element at index 9: 1000
Element at index 10: 1100
Element at index 11: 1200
   at Practice.main(Practice.java:21)
Java Result: 1
BUILD SUCCESSFUL (total time: 3 seconds)

Which seems off to me.. why is the exception thrown halfway through the code? and then finished at the end?

And it points to line 21: anArray[i] = index;

Honestly not a big issue.. i'm just playing around and reviewing some basics of Java (it's been a while...) and the exception is making me feel like I'm doing something wrong but then I'm not sure I actually am because it seems to be working how I intended.

Thank you!

Upvotes: 0

Views: 73

Answers (1)

Christian Tapia
Christian Tapia

Reputation: 34176

Change the for statement:

for (int i=0; i<x; i++){ // Change <= to <
        anArray[i] = index;
        index += 100;
        System.out.println ("Element at index "+ i + ": " + anArray[i]);
    }

If you create an array with length = 12, then you can access it by:

anArray[0]
anArray[1]
...
anArray[11]

But you are accessing it up to anArray[12], so it throws the error.

Upvotes: 2

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