Code not working (Randomize Array)

Question

Hey i wanted to ask for help since i dont know why my code is not working. Im new to android programming and wanted to ask for help.

    public class MotivationalQuotesMenu extends Activity {

    int [] images = {R.drawable.mem1, R.drawable.mem2, R.drawable.mem3};

    public static int[] RandomizeArray(int[] images){
            Random rgen = new Random();  // Random number generator

            for (int i=0; i<images.length; i++) {
                int randomPosition = rgen.nextInt(images.length);
                int temp = images[i];
                images[i] = images[randomPosition];
                images[randomPosition] = temp;
            }

            return images;
        }

@Override

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.motivationalquotesmenu);

        Resources res = getResources();
        memetitles = res.getStringArray(R.array.omg);


        list = (ListView) findViewById(R.id.listView);
        loladapter adapter = new loladapter(this, memetitles, images);
        list.setAdapter(adapter);


    }

And then...

class loladapter extends ArrayAdapter<String> {
        Context context;
//class that shows a specific row in listview

        private loladapter(Context c, String[] titles, int imgs[]) {


            super(c, R.layout.singlerow, R.id.textView, titles);
            this.context = c;
            images = imgs;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            View row = inflater.inflate(R.layout.singlerow, parent, false);
            ImageView myimageie = (ImageView) row.findViewById(R.id.imageView);

            myimageie.setImageResource(images[position]);
            return row;

        }
    }

Random images wont show.. just the same array with the same order

@CollapsedSounds: Where creating object of `loladapter` class please show related part of code — ρяσѕρєя K, Feb 23 '15 at 10:12
Where are you calling `RandomizeArray` method? Can you post that code? — David SN, Feb 23 '15 at 10:16
@ρяσѕρєяK omg im stupid called the method im wrong class. Thanks bro and sorry for such stupid question — , Feb 23 '15 at 10:22

score 1 · Answer 1 · answered Feb 23 '15 at 10:36

1

public static int[] RandomizeArray(int[] images){
       int[] img=images;
       ArrayList<Integer> image= new ArrayList<Integer(Arrays.asList(img));
       Collections.shuffle(image);

        return images;
    }

answered Feb 23 '15 at 10:36

Seema Nagar

91
1
6

score 0 · Answer 2 · edited May 23 '17 at 10:24

In the randomizeArray method you take an array in and create a completely different instance of array. Then you (presumably) take this new instance and store it in a variable while the adapter still holds the original array.

Option 1: Modify the original array

public static void randomizeArray(int[] ar) {
    Random rnd = new Random();
    for (int i = ar.length - 1; i > 0; i--) {
        int index = rnd.nextInt(i + 1);
        // Simple swap
        int a = ar[index];
        ar[index] = ar[i];
        ar[i] = a;
    }
}

Source: https://stackoverflow.com/a/1520212/2444099

After you execute randomizeArray call this to update the associated list view:

mAdapter.notifyDataSetChanged();

Option 2: Update the reference in the adapter

Let the adapter have a method to update images:

public void updateImages(int[] newImages) {
    images = newImages;
    notifyDataSetChanged();
}

Call this method after you obtain new shuffled array.

Out of the scope

Since the int[] images is only relevant to the adapter class, maybe you should move the definition to the adapter class and make the adapter class static to avoid potential memory leaks.

Code not working (Randomize Array)

2 Answers2