CODEWITHSUNDEEP
java
Annie Tan
Annie Tan

Reputation: 27

What causes this ArrayIndexOutOfBoundsException with a simple "for"?

Can someone tell me what's wrong with my array code? the output is correct, but there is some error showing at the bottom of the output.

public static void main(String[] args) {
    // TODO Auto-generated method stub

    int[] number = {1,2,3,4,5};

    System.out.println("Number in ascending order: ");
    for (int x=0; x < number.length; ++x)
        System.out.println(number[x]);

    lasttofirst(number);

}

public static void lasttofirst(int[] number)
{
    System.out.println("Number in descending order: ");
    for (int x=4; x<number.length; --x)
        System.out.println(number [x]+ " ");
}

Upvotes: 1

Views: 350

Answers (4)

Sunil Kumar Sahoo
Sunil Kumar Sahoo

Reputation: 53657

Problem is in following logic

for (int x=4; x<number.length; --x)

when initially x= 4 it is satisfying condition x<number.length because 4<5 then x value becomes 3 for next occurance 3<5 also satisfys ... .. when x value becomes 0 then 0Problem occured Now x value became -1 then -1number[-1] gives you ArrayIndexOutOfBoundsException The array contains data from 0th posiiton to number of element -1 position

Instead of that logic you can use following logic

for (int x=number.length-1; x>=0; --x)
            System.out.println("Index..."+x+"..."+number [x]+ " ");
    }

Upvotes: 3

Alim Ul Gias
Alim Ul Gias

Reputation: 6791

I dont know really understand what you are trying to achieve with your

lastoffirst(number)

But your problem lies here-

for (int x=4; x<number.length; --x)

I can see that the value of number.length is 5 and you are decereasing your loop variable starting from a number smaller than 5. ultimatele at one stage it tries to print number [-1] which is not possible. thats why you are getting that error.

Cheers.

Upvotes: 0

Adam Jurczyk
Adam Jurczyk

Reputation: 2131

You wrongly typed your for loop

If you want to print table elements in backwards, you have to start from last (so, length - 1, cause we index from 0), until x is less than 0.

so it should be:

for(int i=number.length-1; x>=0; --x){
   System.out.println(number[x]); // <-- also you dont need +" ", as printLN inserts new line

}

Upvotes: 1

NPE
NPE

Reputation: 500447

There's an error here:

for (int x=4; x<number.length; --x)

x<number.length should read x >= 0.

Upvotes: 1

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