I am a novice programmer of c back ground and learning java. Can anyone tell me that why this code below gives an error

Question

package javaapplication4;
import java.util.*;

public class Practice {
    public static void main (String[] args){

       int[] a = {12,1,12,3,12,1,1,2,3,3};

       int len = a.length;
       int[] b = new int[len];

       int c;
       int d;
       for (c=0;c<len;c++){

           d=a[c];
           System.out.println(d);

           System.out.println(b[d]);


       }

    }
}

Possible duplicate of [What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?](http://stackoverflow.com/q/5554734/3788176). — Andy Turner, Jun 30 '16 at 13:50

score 2 · Answer 1 · answered Jun 30 '16 at 13:48

2

Error: b[d] when d is equal to a[0], i.e 12

b[12] throws an ArrayIndexOutOfBoundsException

answered Jun 30 '16 at 13:48

Jean Logeart

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score 0 · Answer 2 · answered Jun 30 '16 at 13:49

   int[] a = {12,1,12,3,12,1,1,2,3,3};
               ^--- "d" on you first loop iteration

       System.out.println(b[12]);
                             ^---"d" on the first loop iteration

You don't have 12 elements in your array, you're accessing beyond the end of the array.

score 0 · Answer 3 · answered Jun 30 '16 at 13:50

0

Array index starts from 0. So the last element always has an index of length-of-the-array - 1.

Why is this question tagged C?

answered Jun 30 '16 at 13:50

babon

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score 0 · Answer 4 · answered Jun 30 '16 at 13:51

This array

int[] a = {12,1,12,3,12,1,1,2,3,3};

has only 10 elements.

The array b defined the following way

int len = a.length;
int[] b = new int[len];

also has only 10 elements.

In this statement

System.out.println(b[d]);

you are using the values of elements of the array a as indices for the array b. And it is evident that for example value 12 is greater than the number of elements in b.

I am a novice programmer of c back ground and learning java. Can anyone tell me that why this code below gives an error

4 Answers4