Question

I am having a bit of trouble with android. I have a sorted listview of items retrieved from a database using xml parsing.

i have to display the product on list view with sorted by price

This is my xml feed:

<Feed>
<category>
<Product>
<Name>New Masters of Flash</Name>
<Price>79.99</Price>
</Product>
<Product>
<Name>Professional Java Server Programming</Name>
<Price>63.99</Price>
</Product>
<Product>
<Name>Designing Web Usability</Name>
<Price>80.00</Price>
</Product>
</category>
 </Feed>

This is my android code:

public class Catalogue extends Activity {

// static String URL = "https://dl.dropbox.com/u/48258247/catalogue.json";
static final String URL = "http://192.168.1.168/xcart432pro/internet.xml";

 static String KEY_CATEGORY = "Product";
 static final String KEY_TITLE = "Name";

static final String KEY_DESCRIPTION = "Description";
static final String KEY_COST = "Price"; 
static final String KEY_THUMB_URL = "Image";

ListView list;
ListAdapter adapter;

/** Called when the activity is first created. */
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
     final ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL); // getting XML from URL
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_CATEGORY);

        // looping through all song nodes &lt;song&gt;
        for (int i = 0; i < nl.getLength(); i++) {
            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();
            Element e = (Element) nl.item(i);
            // adding each child node to HashMap key =&gt; value

            map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
           map.put(KEY_DESCRIPTION, parser.getValue(e, KEY_DESCRIPTION));
            map.put(KEY_COST, parser.getValue(e, KEY_COST));
          map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL));

            // adding HashList to ArrayList
            songsList.add(map);
        }

        list=(ListView)findViewById(R.id.listView1);

        // Getting adapter by passing xml data ArrayList
        adapter=new ListAdapter(this, songsList);
        list.setAdapter(adapter);
       // Bundle bundle = getIntent().getExtras();

        // KEY_CATEGORY=bundle.getString(KEY_SUBCATE); 


        // Click event for single list row
        list.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                HashMap<String, String> map = songsList.get(position);
                Intent in = new Intent(
                        Catalogue.this,
                        com.ssmobileproductions.catalogue.SingleMenuItem.class);
                in.putExtra(KEY_TITLE, map.get(KEY_TITLE));
                in.putExtra(KEY_DESCRIPTION, map.get(KEY_DESCRIPTION));
                in.putExtra(KEY_THUMB_URL, map.get(KEY_THUMB_URL));
                in.putExtra(KEY_COST, map.get(KEY_COST));
                startActivity(in);

            }

        });

Here i have to display the product on list view with sorted by price.How can i do.please help me programmatically in android.

Edit:
I have added some code like below:

Button btninsert = (Button) findViewById(R.id.sort);
   btninsert.setOnClickListener(new View.OnClickListener() {

        final ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

    public void onClick(View v) {
        Collections.sort(songsList, new PriceComparator());
    }
    }); 
          final ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();

        XMLParser parser = new XMLParser();
        String xml = parser.getXmlFromUrl(URL); // getting XML from URL
        Document doc = parser.getDomElement(xml); // getting DOM element

        NodeList nl = doc.getElementsByTagName(KEY_CATEGORY);

create one class and wrote the code below:

public class PriceComparator implements Comparator<HashMap<String, String>> {
static final String KEY_COST = "Price"; 

public PriceComparator() {
    // TODO Auto-generated constructor stub

}



public int compare(HashMap<String, String> map1, HashMap<String, String> map2) {
    return map1.get(KEY_COST).compareTo(map2.get(KEY_COST));
}

Now i have to run the app and click the button means nothing is happened????

But i have to display product list is sorted by price.

Answer 1

I believe you need to use a custom Comparator:

Comparator<HashMap<String, String>> comparator = new Comparator<HashMap<String, String>>() {
    @Override
    public int compare(HashMap<String, String> map1, HashMap<String, String> map2) {
        return map1.get(KEY_COST).compareTo(map2.get(KEY_COST));
    }
};

And then sort your list before creating your adapter with:

Collections.sort(songsList, comparator);

---

Addition
You need to do make a few small changes.

1. Make songsList a field variable, like list and adapter:

   ListView list;
   ListAdapter adapter;
   ArrayList<HashMap<String, String>> songsList; // Add me!
   

2. Update how you initialize songsList:

   songsList = new ArrayList<HashMap<String, String>>(); // Shorten me!
   

3. Change your onClick method:

   public void onClick(View v) {
       Collections.sort(songsList, comparator);
       adapter.notifyDataSetChanged(); // Add me!
   }