Java basic integer array

Question

I can't figure out why my outcome is not:

Your first array element is: 0
1
2
3
4
5
6

(the expected output)

My code:

public class day7 {
    public static void main(String[] args){
        int arrayZ[] = new int[7];

        arrayZ[0] = 0;
        System.out.println("Your first array element is: " + arrayZ[0]);

        int i = 1;
        while (i <= 6){
            arrayZ[i] = i;
            i++;
        System.out.println(arrayZ[i]);
        }
    System.out.println("Each entry of the array is: " + arrayZ[0] + " " + arrayZ[1] + " " + arrayZ[2] + " " + arrayZ[3] + " " + arrayZ[4] + " " + arrayZ[5] + " " + arrayZ[6]);
    System.out.println("And, the sum of all array elements are: " + arrayZ[0] + arrayZ[1] + arrayZ[2] + arrayZ[3] + arrayZ[4] + arrayZ[5] + arrayZ[6]);
    }
}

Outcome/actual output:

Your first array element is: 0
0
0
0
0
0

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 7 at day7.main(day7.java:14)

Step through the code in the debugger (e.g. use IntelliJ IDEA) and you'll see where it goes wrong. — Jerry101
– Jerry101, Commented May 9, 2015 at 3:20
When you're using while looping which relies on an inc/decrement sentinel value (i.e.; i in your case) a for loop is generally the more concise option. for (int i = 0; i <= 6; ++i) { ... }. — ChiefTwoPencils
– ChiefTwoPencils, Commented May 9, 2015 at 3:28

Tom · Accepted Answer · 2015-05-09 04:56:35Z

2

Your code is correct only problem is in order of incrementing and printing.

public static void main(String[] args) {
    int arrayZ[] = new int[7];

    arrayZ[0] = 0;
    System.out.println("Your first array element is: " + arrayZ[0]);

    int i = 1;
    while (i <= 6)  {
        arrayZ[i] = i;
        System.out.println(arrayZ[i]);
        i++;
    }
    System.out.println("Each entry of the array is: " + arrayZ[0] + " " + arrayZ[1] + " " + arrayZ[2] + " " + arrayZ[3] + " " + arrayZ[4] + " " + arrayZ[5] + " " + arrayZ[6]);
    System.out.println("And, the sum of all array elements are: " + (arrayZ[0] + arrayZ[1] + arrayZ[2] + arrayZ[3] + arrayZ[4] + arrayZ[5] + arrayZ[6]));
}

Also you need to sum the items first so need to use brackets and then using + with String will convert other variable to String and will show the concatenated result. The output is:

Your first array element is: 0
1
2
3
4
5
6
Each entry of the array is: 0 1 2 3 4 5 6
And, the sum of all array elements are: 21

If you have fixed bounds for your loop counter (in your case they are 1 to 6) then it is better to make use of for loop.

edited May 9, 2015 at 4:56

Tom

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answered May 9, 2015 at 3:40

akhil_mittal

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2 Comments

Jay da science noob Over a year ago

Thank you very much. Your comment is crystal clear and very helpful.

Janak Dhanani Over a year ago

You just have to replace by i++ to System.out line ...because its array will bound on last index by i++.

DoubleMa · Accepted Answer · 2015-05-09 03:21:17Z

just switch the lines between i++ and System.out.println(arrayZ[i]);

and if you want calculate the sum just add them in a new variable or use ();

public static void main(String[] args) {
    int arrayZ[] = new int[7];

    arrayZ[0] = 0;
    System.out.println("Your first array element is: " + arrayZ[0]);

    int i = 1;
    while (i <= 6) {
        arrayZ[i] = i;
        System.out.println(arrayZ[i]);
        i++;
    }
    System.out.println("Each entry of the array is: " + arrayZ[0] + " " + arrayZ[1] + " " + arrayZ[2] + " " + arrayZ[3] + " " + arrayZ[4] + " " + arrayZ[5] + " " + arrayZ[6]);
    System.out.println("And, the sum of all array elements are: " + (arrayZ[0] + arrayZ[1] + arrayZ[2] + arrayZ[3] + arrayZ[4] + arrayZ[5] + arrayZ[6]));
}

Raphael Amoedo · Accepted Answer · 2015-05-09 03:21:35Z

1

Change to this:

while (i <= 6){
    arrayZ[i] = i;
    System.out.println(arrayZ[i]);
    i++;
}

Because the way you were using it, it tries to print arrayZ[7], that not exists.

answered May 9, 2015 at 3:21

Raphael Amoedo

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1 Comment

Jay da science noob Over a year ago

That was what I thought. :3

user7088977 · Accepted Answer · 2017-05-26 18:11:54Z

just switch the lines between i++ and System.out.println(arrayZ[i]);

and if you want calculate the sum just add them in a new variable or use ();

public static void main(String[] args) {
int arrayZ[] = new int[7];

arrayZ[0] = 0;
System.out.println("Your first array element is: " + arrayZ[0]);

int i = 1;
while (i <= 6) {
    arrayZ[i] = i;
    System.out.println(arrayZ[i]);
    i++;
}
System.out.println("Each entry of the array is: " + arrayZ[0] + " " + arrayZ[1] + " " + arrayZ[2] + " " + arrayZ[3] + " " + arrayZ[4] + " " + arrayZ[5] + " " + arrayZ[6]);
System.out.println("And, the sum of all array elements are: " + (arrayZ[0] + arrayZ[1] + arrayZ[2] + arrayZ[3] + arrayZ[4] + arrayZ[5] + arrayZ[6]));

}

Kristof Mols · Accepted Answer · 2017-06-27 08:30:57Z

-1

change while loop code as follows

while (i <= 6){
    arrayZ[i] = i;
    System.out.println(arrayZ[i]);
    i++;
}

edited Jun 27, 2017 at 8:30

Kristof Mols

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answered Jun 26, 2017 at 15:28

ThilinaMD

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