ArrayOutOfIndexException android

Question

I have an arrayoutofindexexception in my code below:

    ImageView[] bObject = new ImageView[9];

    private void getCorrectObject() {

    List<Integer> objects = new ArrayList<Integer>();
    objects.add(1);
    objects.add(2);
    objects.add(3);
    objects.add(4);
    objects.add(5);
    objects.add(6);
    objects.add(7);
    objects.add(8);
    objects.add(9);

    Collections.shuffle(objects);
    int correctObject =  objects.get(0);
    Log.d("test", String.valueOf(correctObject));

            bObject[correctObject + 1].setImageResource(R.drawable.stage1_4_object1);
    bObject[correctObject + 1].setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
                goToNextQuestion();
            }
        });
            }


           //TODO initControls
private void initControls() {

    bObject[0] = (ImageView) findViewById(R.id.bObject1Stage1_4);
    bObject[0].setImageResource(R.drawable.stage1_4_object2);
    bObject[1] = (ImageView) findViewById(R.id.bObject2Stage1_4);
    bObject[1].setImageResource(R.drawable.stage1_4_object2);
    bObject[2] = (ImageView) findViewById(R.id.bObject3Stage1_4);
    bObject[2].setImageResource(R.drawable.stage1_4_object2);
    bObject[3] = (ImageView) findViewById(R.id.bObject4Stage1_4);
    bObject[3].setImageResource(R.drawable.stage1_4_object2);
    bObject[4] = (ImageView) findViewById(R.id.bObject5Stage1_4);
    bObject[4].setImageResource(R.drawable.stage1_4_object2);
    bObject[5] = (ImageView) findViewById(R.id.bObject6Stage1_4);
    bObject[5].setImageResource(R.drawable.stage1_4_object2);
    bObject[6] = (ImageView) findViewById(R.id.bObject7Stage1_4);
    bObject[6].setImageResource(R.drawable.stage1_4_object2);
    bObject[7] = (ImageView) findViewById(R.id.bObject8Stage1_4);
    bObject[7].setImageResource(R.drawable.stage1_4_object2);
    bObject[8] = (ImageView) findViewById(R.id.bObject9Stage1_4);
    bObject[8].setImageResource(R.drawable.stage1_4_object2);

            for (ImageView bObj  : bObject) {
                   bObj.setOnClickListener(this);
            }

I'm getting an error in this line:

        bObject[correctObject + 1].setImageResource(R.drawable.stage1_4_object1);

I don't know what's wrong with this. If you find what's wrong, any help is truly appreciated. Thanks

Reimeus · Accepted Answer · 2013-04-26 15:49:17Z

5

Arrays are zero based. Here the values used exceed the bounds of the array bObject. Use

Add values to the List starting from 0:

objects.add(0);
...
objects.add(8);

and use:

bObject[correctObject].setImageResource(...);

Alternatively, you can use:

for (int i=0; i < bObject.length; i++)
   objects.add(i);
}

This will remove the need to hard code index values.

To eliminate the objects index List completely, Random#nextInt can be used, for example:

bObject[random.nextInt(bObject.length)].setImageResource(...);

edited Apr 26, 2013 at 15:49

answered Apr 26, 2013 at 14:57

Reimeus

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2 Comments

neknek mouh Over a year ago

Okay so what happens to the correctObject? Since I set it equal to objects(0);?

Reimeus Over a year ago

There is no issue. After the shuffle you are retrieving the value at index 0. Once the values are with the index range an ArrayOutOfIndexException will not occur

Gabe Sechan · Accepted Answer · 2013-04-26 14:58:18Z

0

Arrays are 0 based in Java- the first index is 0. So bObject has valid range of 0...8. The value of correctObject will be random 1...9. Adding 1 to it will bring 2...10. So if you get a 9 or 10 you're accessing out of range of the array. A 20% chance you'll do that and crash.

You probably wanted to subtract 1, not add it.

answered Apr 26, 2013 at 14:58

Gabe Sechan

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Comments

Serhat YILMAZ · Accepted Answer · 2013-04-26 15:00:52Z

0

You should say bObject[correctObject - 1].setImageResource(R.drawable.stage1_4_object1);

because correctobject value could be 9 and max index you could give to bObject is 8.

answered Apr 26, 2013 at 15:00

Serhat YILMAZ

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