Adding random and unique images to imageviews android

Question

I have 16 imageviews on an activity......named img1->img16. I want a diff image on each image view and this cannot be hardcoded, depening on what number is passed as an extra, e.g. 1, 2 , 3..... the images added to these views must be different.

I currently have code that adds 16 images but these are not unique..... they are duplicated...

        int[] imageViews = {
            R.id.img1, R.id.img2,
            R.id.img3, R.id.img4,
            R.id.img5, R.id.img6,
            R.id.img7, R.id.img8,
            R.id.img9, R.id.img10,
            R.id.img11, R.id.img12,
            R.id.img13, R.id.img14,
            R.id.img15, R.id.img16
            };

    int[] images = {
            R.drawable.img1, R.drawable.img2,
            R.drawable.img3, R.drawable.img4,
            R.drawable.img5, R.drawable.img6,
            R.drawable.img7, R.drawable.img8,
            R.drawable.img9, R.drawable.img10,
            R.drawable.img11, R.drawable.img12,
            R.drawable.img13, R.drawable.img14,
            R.drawable.img15, R.drawable.img16
            };


    Random random = new Random(System.currentTimeMillis());

        for(int v : imageViews) 
        {
                ImageView iv = (ImageView)findViewById(v);
                iv.setImageResource(images[random.nextInt(images.length - 1)]);
        }

And also, if possible, i need it so that the images are not hard coded in the images array as they will be different depending on what number has been passed.

So these images are for the number 1, but if number 2 was passed to the activity, the images would be different.

all the details are saved in a local database and the images are all in the drawable folder and will all follow the same naming styles e.g. img1 all the way to say img100....

Many thanks in advance.

/UPDATE/

Hi, I have tried that with the following code:

Random random = new Random(System.currentTimeMillis());
    List<Integer> generated = new ArrayList<Integer>();
        for(int v : imageViews) 
        {
             int next = random.nextInt(15) + 1;
             if (!generated.contains(next))
             {
                generated.add(next);
                ImageView iv = (ImageView)findViewById(v);
                iv.setImageResource(images[next]);
             }
        }

I may be doing it completely wrong there i guess.... but so far i have not found a duplicate, but does not help with the gaps, its as if it maybe generates 16 random ints but only adds the ones that are unique, rather than generating till reaches 16 unique images if you understand?

Any ideas on that front?

So the only issue you're having is that your current method allows duplicates? — Jason Robinson, Jun 04 '12 at 17:30
Yes, and sometimes when you access the activity, some images are missing, the imageview is still there but there may be a gap where an image should be — Dean 'Amstrad' Woodford, Jun 04 '12 at 17:33

Jason Robinson · Accepted Answer · 2012-06-04T17:59:26.357

1

Whenever you get your next random int, hold that value in an array. Then the next time you get a random int, check to see if that number has already been picked. If it has, repeat the process until a non-chosen int has been selected.

Edit: Try this code:

Random random = new Random( System.currentTimeMillis() );
List<Integer> generated = new ArrayList<Integer>();
for (int i = 0; i < imageViews.length; i++) {

    int v = imageViews[i];
    int next = random.nextInt( 15 ) + 1;
    if ( !generated.contains( next ) ) {
        generated.add( next );
        ImageView iv = (ImageView) findViewById( v );
        iv.setImageResource( images[next] );
    }
    else {
        i--;
    }
}

edited Jun 04 '12 at 17:59

answered Jun 04 '12 at 17:39

Jason Robinson

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I have updated my post......I have tried some code for that but if you see my original post now I explain a problem with it – Dean 'Amstrad' Woodford Jun 04 '12 at 17:53
Just tried something similar to that without the i-- and just tried yours but both cause the same problem, once you load the activity it hangs on a black screen for several seconds before it asks to force close....... – Dean 'Amstrad' Woodford Jun 04 '12 at 18:04
@Dean'Amstrad'Woodford I think it needs to be `random.nextInt(16) + 1`, as that method will find a random number in the range [0,n). – Jason Robinson Jun 04 '12 at 18:06
Im not sure what the problem is, but as soon as I set to 16 it causes an exception straight away, java.lang.ArrayIndexOutOfBoundsException: length=16; index=16 – Dean 'Amstrad' Woodford Jun 04 '12 at 18:14
Ok fixed the problem, set to 16 but take away the +1...... thank you for the help :) – Dean 'Amstrad' Woodford Jun 04 '12 at 18:20

Adding random and unique images to imageviews android

1 Answers1