Show data from json object to android listview

Question

I am developing an android app which sends simple data as NAME to a webserver and can retreive NAMES from server. Using php and mysql for webservices. currently i am done with sending and recieving data from web to android. Now i want to show names that i get from my website database to my android listview. Following is my code

public class allProducts extends ListActivity {

// Progress Dialog
private ProgressDialog pDialog;

// Creating JSON Parser object
JSONParser jParser = new JSONParser();

ArrayList<HashMap<String, String>> productsList;

// url to get all products list
private static String url_all_products = "http://10.0.2.2/dinein/Model/getName.php";

// JSON Node names

private static final String TAG_NAME = "name";
//private static final String TAG_SUCCESS = "success";
//private static final String TAG_PRODUCTS = "products";
//private static final String TAG_PID = "pid";

// products JSONArray
JSONArray products = null;
static ArrayList<String> listItems=new ArrayList<String>();

//DEFINING STRING ADAPTER WHICH WILL HANDLE DATA OF LISTVIEW
ArrayAdapter<String> adapter;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.products);


    // Hashmap for ListView
    productsList = new ArrayList<HashMap<String, String>>();

    // Loading products in Background Thread
    new LoadAllProducts().execute();

    // Get listview
    ListView lv = getListView();

    // on seleting single product
    // launching Edit Product Screen
   /* lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            // getting values from selected ListItem
            String pid = ((TextView) view.findViewById(R.id.pid)).getText()
                    .toString();

            // Starting new intent
            Intent in = new Intent(getApplicationContext(),
                    EditProductActivity.class);
            // sending pid to next activity
            in.putExtra(TAG_PID, pid);

            // starting new activity and expecting some response back
            startActivityForResult(in, 100);
        }
    });*/

}

// Response from Edit Product Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    // if result code 100
    if (resultCode == 100) {
        // if result code 100 is received
        // means user edited/deleted product
        // reload this screen again
        Intent intent = getIntent();
        finish();
        startActivity(intent);
    }

}

 class LoadAllProducts extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(allProducts.this);
        pDialog.setMessage("Loading products. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();
    }

    /**
     * getting All products from url
     * */
    protected String doInBackground(String... args) {
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // getting JSON string from URL
        JSONObject json =jParser.makeHttpRequest(url_all_products, "POST", params);

        // Check your log cat for JSON reponse




            // Checking for SUCCESS TAG
            int success = 1;

            if (success == 1) {
                Iterator<String> iter = json.keys();
                Object value=null;
                while (iter.hasNext()) {
                    String key = iter.next();
                    try {
                         value = json.get(key);


                    } catch (JSONException e) {
                        // Something went wrong!
                    }
                }

              }



        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url) {
        // dismiss the dialog after getting all products
        pDialog.dismiss();
        // updating UI from Background Thread
        runOnUiThread(new Runnable() {
            public void run() {
                /**
                 * Updating parsed JSON data into ListView
                 * */
                ListAdapter adapter = new SimpleAdapter(
                        allProducts.this, productsList,
                        R.layout.name_list, new String[] {TAG_NAME},
                        new int[] { R.id.pid, R.id.name });
                // updating listview
                setListAdapter(adapter);
            }
        });

    }

}

I want to show my data in my activity with list view. Here is how my xml files look like

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<ListView
    android:id="@+id/list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>

and the other one

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
    android:id="@+id/pid"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:visibility="gone" />

</RelativeLayout>

Answer 1

I found two mistakes on your code.

First of all, you are not able to see anything on your list because the row's textview visibility is set to GONE. So, change it.

<TextView
     android:id="@+id/pid"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
    <!-- android:visibility="gone" -->
 />

Second, your list row has only one field(R.id.pid), and your code is trying to set two fields(R.id.pid, R.id.name). Soon, you have two change it, or add another textview with android:id ="@+id/name" or remove R.id.name of your adapter.

Here a example that works using only your pid field:

   List<Map<String, String>> productsList = new ArrayList<Map<String,String>>();
   HashMap<String, String> p1 = new HashMap<String, String>();
   p1.put("key", "product1");
   HashMap<String, String> p2 = new HashMap<String, String>();
   p2.put("key", "product2");
   HashMap<String, String> p3 = new HashMap<String, String>();
   p3.put("key", "product3");
   productsList.add(p1);
   productsList.add(p2);
   productsList.add(p3);


   ListAdapter adapter = new SimpleAdapter(this, productsList,
            R.layout.row, new String[] {"key"},
            new int[] { R.id.pid});

   ListView listview = getListView();
   listview.setAdapter(adapter);

Answer 2

if you are extending ListActivity then ListView id must be android:id="@+id/android:list" .change your xml as :

<ListView
    android:id="@+id/android:list"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"/>

because onPostExecute is always executed on Main UI Thread then no need to use runOnUiThread for updating UI from onPostExecute method of doInBackground change your onPostExecute method code as :

protected void onPostExecute(String file_url) {
        // dismiss the dialog after getting all products
        pDialog.dismiss();

        ListAdapter adapter = new SimpleAdapter(
                        allProducts.this, productsList,
                        R.layout.name_list, new String[] {TAG_NAME},
                        new int[] { R.id.pid, R.id.name });

               ListView listview = allProducts.this.getListView();
                // updating listview
                listview.setListAdapter(adapter);
    }