Deleting item from a Custom ListView

Question

I have a Custom ListView which is populated with retrieved from a database. Now, what I can't understand is how to remove an item from the list: searching on Google I've seen different questions without a standard solution, so I have doubts about this. How can I delete a row from a CustomListView also using Async Task?

Here is Leggi_Pizzaiolo activity (where I display the listView):

public class Leggi_Pizzaiolo extends Activity
{
    // Progress Dialog
    private ProgressDialog pDialog;
    public List list = new LinkedList();
    // 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/tesina/Leggi_Pizzaiolo.php";

    // JSON Node names
    private static final String TAG_SUCCESS = "Esito";
    private static final String TAG_PRODUCTS = "comande";
    private static final String TAG_PID = "ID";
    private static final String TAG_NAME = "Nome";
    private static final String TAG_TABLE = "Tavolo";
    public ListView lv;
    // products JSONArray
    JSONArray products = null;

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

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

        // Loading products in Background Thread

        // Get listview
        lv = (ListView)findViewById(R.id.lista);

        new LoadAllProducts().execute();

    }

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class LoadAllProducts extends AsyncTask<String, String, String> 
    {

        /**
         * Before starting background thread Show Progress Dialog
         * */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(Leggi_Pizzaiolo.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, "GET", params);

            // Check your log cat for JSON reponse
            Log.d("All Products: ", json.toString());

            try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Products
                    products = json.getJSONArray(TAG_PRODUCTS);

                    // looping through All Products
                    for (int i = 0; i < products.length(); i++) {
                        JSONObject c = products.getJSONObject(i);

                        // Storing each json item in variable
                        int id = c.getInt(TAG_PID);
                        String name = c.getString(TAG_NAME);
                        int Tavolo= c.getInt(TAG_TABLE);

                        list.add(new Comanda(name, id, Tavolo));

                    }
                } else {
                    // no products found
                    // Launch Add New product Activity
                    Intent i = new Intent(getApplicationContext(),
                            Listino.class);
                    // Closing all previous activities
                    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(i);
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            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 listview
            final ComandaCursorAdapter adapter = new ComandaCursorAdapter(Leggi_Pizzaiolo.this, R.layout.comanda_cuoco, list);
            lv.setAdapter(adapter);


        }



    }


} 

This is the CursorAdapter:

public class ComandaCursorAdapter extends ArrayAdapter<Comanda>
{

public ComandaCursorAdapter(Context context, int comandaCuoco, List list) {
    super(context, comandaCuoco, list);
    // TODO Auto-generated constructor stub
}


@Override
public View getView(int position, View convertView, ViewGroup parent)
{
    LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    convertView = inflater.inflate(R.layout.comanda_cuoco, null);

    TextView Nome = (TextView)convertView.findViewById(R.id.Comanda);
    TextView Tavolo = (TextView)convertView.findViewById(R.id.Tavolo);
    TextView Codice = (TextView)convertView.findViewById(R.id.Codice);

    Comanda c = getItem(position);

    Nome.setText(c.getNome());
    Tavolo.setText("Tavolo: " + Integer.toString(c.getTavolo()));
    Codice.setText("Codice: " + Integer.toString(c.getCodice()));


    return convertView;

}

And this is the object Comanda:

public class Comanda {

    private String Nome;
    private int Codice;
    private int Tavolo;

    public Comanda(String Nome, int Codice, int Tavolo)
    {
        this.Nome = Nome;
        this.Codice = Codice;
        this.Tavolo = Tavolo;

    }

    public String getNome()
    {
        return Nome;
    }

    public void setNome(String Nome)
    {
        this.Nome = Nome;
    }

    public int getCodice()
    {
        return Codice;
    }

    public void setCodice(int Codice)
    {
        this.Codice = Codice;
    }

    public int getTavolo()
    {
        return Tavolo;
    }

    public void setTavolo(int Tavolo)
    {
        this.Tavolo = Tavolo;
    }


}

Now, where I have to declare the setOnItemClickListener in Leggi_Pizzaiolo activity? Should I have to implement a remove method into the class or something? Please let me know how...

Answer 1

Now, what I can't understand is how to remove an item from the list

No, normally create for example OnItemClickListener() to be able to handle click events on ListView. Then in onItemClick() you have parameter int position that returns position of item in Adapter. Now you need to remove item from your List and then perform

list.remove(position)

and then you need to call

adapter.notifyDataSetChanged();

to notify Adapter that datasource has changed.

Note: For more comfort you can show after click on ListItem some AlertDialog with buttons for deleting or not.

Answer 2

Try this

 lv.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> a, View v, int position, long id) {
        AlertDialog.Builder adb=new AlertDialog.Builder(MyActivity.this);
        adb.setTitle("Delete?");
        adb.setMessage("Are you sure you want to delete " + position);
        final int positionToRemove = position;
        adb.setNegativeButton("Cancel", null);
        adb.setPositiveButton("Ok", new AlertDialog.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                MyDataObject.remove(positionToRemove);
                adapter.notifyDataSetChanged();
            }});
        adb.show();
        }
    });

where lv is your listview,adb is a dialog, mydataobject is the collection you are using to populate your listview and adapter is your adapter.