How to avoid ArrayIndexOutOfBoundsException?

Question

i can't load images on gridview, it always crashes. log cat message "ArrayIndexOutOfBoundsException length=16 ; index=16"
here is my code :

public Integer[] mThumbIds = {
        R.drawable.pic_1, R.drawable.pic_2,
        R.drawable.pic_3, R.drawable.pic_4,
        R.drawable.pic_5, R.drawable.pic_6,
        R.drawable.pic_7, R.drawable.pic_8,
        R.drawable.pic_9, R.drawable.pic_10,
        R.drawable.pic_11, R.drawable.pic_12,
        R.drawable.pic_13, R.drawable.pic_14,
        R.drawable.pic_15, R.drawable.pic_16,
        R.drawable.pic_17, R.drawable.pic_18,
        R.drawable.pic_19, R.drawable.pic_20,
        ........ R.drawable.pic_96 
        };

code :

@Override
public View getView(int position, View convertView, ViewGroup parent) { 

    int width = metrics.widthPixels / 6;
    int height = metrics.heightPixels / 6;

    ImageView i;     
        i = new ImageView(mContext);
        i.setLayoutParams(new GridView.LayoutParams(height, height));
        i.setScaleType(ImageView.ScaleType.CENTER_CROP);                         
    }

    if(mImageSet == IMAGE_SET_ONE) {           
        Integer[] images1 = new Integer[16];         
        System.arraycopy(mThumbIds, 0, images1, 0, 16);    
        i.setImageResource(images1[position]);
    } else if(mImageSet == IMAGE_SET_THREE) {

    ...........    
 }

    return i;       
}

Please help me..

what is the calling code? I presume it is failing on getItem(int position) — RNJ, Jul 22 '13 at 14:55
array indices start with zero. So, a 16-element array goes from 0 - 15. — GriffeyDog, Jul 22 '13 at 14:56
Can you not just use try/catch to catch the exception? and deal with it then? — rcbevans, Jul 22 '13 at 15:02

kosa · Answer 1 · 2013-07-22T15:01:21.217

2

One thing I would suggest is, make sure position is less than mThubIds array length in following method. Array index starts from ZERO, if position is greater (or) equal to mThumbIds length, you will get ArrayIndexOutofBoundsException.

@Override
public Object getItem(int position) {
    return mThumbIds[position];
}

Example:

 @Override
    public Object getItem(int position) {
        if(position < mThumbIds.length){
        return mThumbIds[position];
        }
      return null;
    }

edited Jul 22 '13 at 15:01

answered Jul 22 '13 at 14:56

kosa

65,990
13
130
167

Compile error, no return from getItem. – Pete B. Jul 22 '13 at 15:00
@PeteBelford: Correct, fixed. Thanks for pointing. – kosa Jul 22 '13 at 15:01

score 0 · Answer 2 · answered Jul 22 '13 at 14:57

0

@Override
public Object getItem(int position) {
    if(position >= mThumbIds.length) return null;
    return mThumbIds[position];
}

Please shoot yourself for using hungarian notation.

answered Jul 22 '13 at 14:57

Pete B.

3,188
6
25
38

How is he using Hungarian notation? Wouldn't that become `iwImgView` or `vMyImageView` ? :) – Shark Jul 22 '13 at 15:01
mThumbIds, m for member. No matter, it is terrible. – Pete B. Jul 22 '13 at 15:02
I thought that `m`-ing was a C++ tell. Then again I think it's really a cheap student's way of not having to use `this.` – Shark Jul 22 '13 at 15:22

score 0 · Answer 3 · answered Jul 22 '13 at 15:04

0

Integer[] images1 = new Integer[16];         
System.arraycopy(mThumbIds, 0, images1, 0, 16);    
i.setImageResource(images1[position]);

you copy the first 16 Integer, from mThumbIds inside images1, but since mThumbIds containse more than 16 elements your position can be assume a value between 0 and mThumbIds.lenght - 1 . When position is 16 you get your ArrayIndexOutofBoundsException. You should use i.setImageResource(mThumbIds[position]);

answered Jul 22 '13 at 15:04

Blackbelt

156,034
29
297
305

if i use i.setImageResource(mThumbIds[position]); it will not take all elements on mThumbIds? – Paul Nababan Jul 22 '13 at 15:34
It will take the element at index position. What is your purpose? – Blackbelt Jul 22 '13 at 15:35
i want to load 16 images/elements from mThumbIds for gridView. so i copy 16 first from mThumbIds to array images1 and setImagesResources from images1. – Paul Nababan Jul 22 '13 at 15:46
then let getCount return 16, and use mThumbIds. There is no need to copy it – Blackbelt Jul 22 '13 at 15:48

How to avoid ArrayIndexOutOfBoundsException?

3 Answers3