Question

Here is my view pager adapter to load fragments. Inside the getItem() method, I am trying to insert the values dynamically using the index passed to that function. I have all the data inside productData. But it always fetches the value of

 productData.get(0).get("name")

into all the fragments. The index value is correctly being passed into fragments. I verified it. And also the data inside the productData is also correct. Where is the issue here?

  public class ProductViewPagerAdapter extends FragmentPagerAdapter {
    public ProductViewPagerAdapter(FragmentManager fm) {
        super(fm);
    }
    @Override
    public Fragment getItem(int i) {            
        Fragment fragment = new ProductViewFragment();
        Bundle args = new Bundle();
        args.putInt("number", i + 1);
        args.putString("name", productData.get(i).get("name"));
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public int getCount() {
        return 10;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0: return "test1";
            case 1: return "2";
            case 2: return "3";
            case 3: return "4";
        }
        return null;
    }     

 }

Answer 1

The problem is that you only have a single HashMap. Even though you keep changing the data inside the HashMap, the list productItems just contains 10 references to the single HashMap. So in the end, it will contain 10 copies of the final set of data.

What you want to do is create a new HashMap for each loop iteration. Here’s the modified code:

public ArrayList<HashMap<String,String>> getData(AsyncTask<Void, Void, Void> asynctask, String query) throws URISyntaxException
{
    api_url += query;
    //  Log.v("API url",api_url);
    XMLParser parser = new XMLParser();
    String xml = parser.getXmlFromUrl(api_url); // getting XML
    Document doc = parser.getDomElement(xml); // getting DOM element
    NodeList nl = doc.getElementsByTagName(KEY_PRODUCT);
    ArrayList<HashMap<String, String>> productItems = new ArrayList<HashMap<String, String>>();
    for (int i = 0; i < 10; i++) {
        Element e = (Element) nl.item(i);           
        // adding each child node to HashMap key => value
        HashMap<String, String> map = new HashMap<String, String>();
        map.put(KEY_PROD_NAME, e.getAttribute(KEY_PROD_NAME));
        map.put(KEY_ID, e.getAttribute(KEY_MER_ID));
        map.put(KEY_PRICE, e.getAttribute(KEY_MER_PRICE));      
        Log.v("fsd:",e.getAttribute(KEY_PROD_NAME));
        // adding HashList to ArrayList
        productItems.add(map);      
    }       
    return productItems;    
}