returning incorrect position in getView method

Question

I am using CustomGridAdapter which extends BAseAdapter to display the values of array in a listview. but in the getView of the CustomGridAdapter the position of the array values is not in a flow.

public class CustomGridAdapter extends BaseAdapter {

    private Context context; 
    private final String[] gridValues;
    private final String[] gridImage;

    //Constructor to initialize values
    public CustomGridAdapter(Context context, String[] gridValues, String[] gridImage) {
        this.context = context;
        this.gridValues = gridValues;
        this.gridImage=gridImage;
    }

    @Override
    public int getCount() {

        // Number of times getView method call depends upon gridValues.length
        return gridValues.length;
    }

    @Override
    public Object getItem(int position) {

        return gridValues[position];
    }

    @Override
    public long getItemId(int position) {

        return 0;
    }


    // Number of times getView method call depends upon gridValues.length

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

        //LayoutInflator to call external grid_item.xml file

        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        View gridView;

        if (convertView == null) {

            gridView = new View(context);

            // get layout from grid_item.xml
            gridView = inflater.inflate(R.layout.grid_item, null);

            // set value into textview

            TextView textView = (TextView) gridView.findViewById(R.id.grid_item_label);
            textView.setText(gridValues[position]);
            Log.i(new Integer(position).toString(),gridValues[position] );
            ImageView grp_icon=(ImageView)gridView.findViewById(R.id.grid_item_image);
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inPreferredConfig = Bitmap.Config.ARGB_8888;
            String path="/sdcard/Letsmeet/letsmeet_media/group_images/"+gridImage[position];
            Bitmap bitmap = BitmapFactory.decodeFile(path, options);
            grp_icon.setImageBitmap(bitmap);
            // set image based on selected text

            ImageView imageView = (ImageView) gridView
                    .findViewById(R.id.grid_item_image);

            String mobile = gridValues[position];



        } else {
            gridView = (View) convertView;
        }

        return gridView;
    }
}

In the getView method of the customGridAdapter the postion is in order of 0,1,2,0,4 Why I am getting 0 after 2 instead of 3?

Answer 1

@Override
public long getItemId(int position) {

    return position; //return position here
}

Make your getView as,

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

    //LayoutInflator to call external grid_item.xml file

    LayoutInflater inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    View gridView;

    if (convertView == null) {

        gridView = new View(context);

        // get layout from grid_item.xml
        gridView = inflater.inflate(R.layout.grid_item, null);

        // set value into textview

        TextView textView = (TextView) gridView.findViewById(R.id.grid_item_label);
        textView.setText(gridValues[position]);
        Log.i(new Integer(position).toString(),gridValues[position] );
        ImageView grp_icon=(ImageView)gridView.findViewById(R.id.grid_item_image);        



    } else {
        gridView = (View) convertView;
    }

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        String path="/sdcard/Letsmeet/letsmeet_media/group_images/"+gridImage[position];
        Bitmap bitmap = BitmapFactory.decodeFile(path, options);
        grp_icon.setImageBitmap(bitmap);
        // set image based on selected text

        ImageView imageView = (ImageView) gridView
                .findViewById(R.id.grid_item_image);

        String mobile = gridValues[position];

    return gridView;
}

Your converView is null only for the number of Views shown initially on the screen. Once you scroll them converView != null and they are recycled. So move your code outside it.

Answer 2

This is related to how ListView and classes inherited from ListView display results based on scroll position and other factors for GC/performance reasons. It is specified in the documentation that there is no guarantee the order or positions. To counter this it is recommended that you use the ID rather than position of items for referencing.

@Override
public long getItemId(int position) {
    return super.getItemId(position);
}

For more information see: https://www.youtube.com/watch?v=wDBM6wVEO70

Answer 3

You just use like this and you will take it as a example and edit your custom adapter like this and you can get the Out put I think you have done the mistake in convert view

You just delete the condition of convetview ... and use like this

 public class CustomAdapter extends ArrayAdapter<Sample> {

public ArrayList<Sample> mlist;
public Context context;
public LayoutInflater inflater;

public CustomAdapter(Context context, int resource, ArrayList<Sample> mlist) {
    super(context, resource);
    this.mlist = mlist;
    this.context = context;
    inflater = (LayoutInflater) context
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getPosition(Sample item) {
    return super.getPosition(item);
}

@Override
public Sample getItem(int position) {
    return mlist.get(position);
}

@Override
public int getCount() {
    return mlist.size();
}

@Override
public long getItemId(int position) {
    return super.getItemId(position);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    convertView = inflater.inflate(R.layout.listitem, null);
    TextView text1 = (TextView) convertView.findViewById(R.id.item1);
    TextView text2 = (TextView) convertView.findViewById(R.id.item2);
    text1.setText(mlist.get(position).getListitem1());
    text2.setText(mlist.get(position).getListitem2());
    text2.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // you just put your Logic here And use this custom adapter to
            // load your Data By using this particular custom adapter to
            // your listview

        }
    });
    return convertView;
}

   }