Develop Reference

I want to pass some argument get from intent to doBackground

This is my code,it gets detail from previous activity:it get two values as location and bloodGroup and SearchDonor will get it and process it.
Intent intent =getIntent();
location = intent.getStringExtra("location");
bloodgroup = intent.getStringExtra("bloodgroup");
so iget an when i write it in doBackGround process,i want to add above code in following code
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class SearchDonor extends ListActivity {
private Context context;
private static String url = "http://10.0.2.2/bl/getDonor.php";
private static final String TAG_FIRSTNAME = "FirstName";
private static final String TAG_MIDDLENAME = "MiddleName";
private static final String TAG_LASTNAME = "LastName";
private static final String TAG_ADDRESS = "Address";
private static final String TAG_CELLPHONE = "CellPhone";
private static final String TAG_DONORS = "donors";
private static final String TAG_SUCCESS = "success";
private static final String TAG_DONORID = "Donor_ID";
private static final String TAG_LOCATION = "location";
private static final String TAG_BLOODGROUP = "bloodgroup";
JSONArray donors = null;
ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>();
ListView lv ;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_donor);
new ProgressTask(SearchDonor.this).execute();
}
#Override
protected void onListItemClick(ListView l,View v,int position,long id)
{
Intent intent = new Intent(this,DonorDetails.class);
String did=( (TextView)v.findViewById(R.id.donorId)).getText().toString();
String Name=( (TextView)v.findViewById(R.id.vehicleType)).getText().toString();
String Address=( (TextView)v.findViewById(R.id.vehicleColor)).getText().toString();
String cellphone=( (TextView)v.findViewById(R.id.fuel)).getText().toString();
intent.putExtra("did", did);
intent.putExtra("Name", Name);
intent.putExtra("Address", Address);
intent.putExtra("cellPhone", cellphone);
startActivity(intent);
}
private class ProgressTask extends AsyncTask<String, Void, Boolean> {
private ProgressDialog dialog;
private ListActivity activity;
// private List<Message> messages;
public ProgressTask(ListActivity activity) {
this.activity = activity;
context = activity;
dialog = new ProgressDialog(context);
}
/** progress dialog to show user that the backup is processing. */
/** application context. */
private Context context;
protected void onPreExecute() {
this.dialog.setMessage("Progress start");
this.dialog.setIndeterminate(false);
this.dialog.setCancelable(false);
this.dialog.show();
}
#Override
protected void onPostExecute(final Boolean success) {
if (dialog.isShowing()) {
dialog.dismiss();
}
ListAdapter adapter = new SimpleAdapter(context, jsonlist,
R.layout.list_item, new String[] { TAG_DONORID,TAG_FIRSTNAME , TAG_ADDRESS,
TAG_CELLPHONE }, new int[] {
R.id.donorId,R.id.vehicleType, R.id.vehicleColor, R.id.fuel });
setListAdapter(adapter);
// selecting single ListView item
lv = getListView();
}
protected Boolean doInBackground(final String... args) {
JSONParser jParser = new JSONParser();
List<NameValuePair>params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair(TAG_LOCATION,location));
params.add(new BasicNameValuePair(TAG_BLOODGROUP,bloodgroup));
JSONObject json = jParser.makeHttpRequest(url,"GET",params);
// getting JSON string from URL
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
donors = json.getJSONArray(TAG_DONORS);
// looping through All Products
for (int i = 0; i < donors.length(); i++) {
JSONObject c = donors.getJSONObject(i);
String donoID = c.getString(TAG_DONORID);
String firstName = c.getString(TAG_FIRSTNAME );
String middleName = c.getString(TAG_MIDDLENAME );
String lastName = c.getString(TAG_LASTNAME );
String address = c.getString(TAG_ADDRESS );
String cellPhone = c.getString(TAG_CELLPHONE );
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_DONORID, donoID);
// adding each child node to HashMap key => value
map.put(TAG_FIRSTNAME, firstName);
map.put(TAG_MIDDLENAME, middleName);
map.put(TAG_LASTNAME ,lastName);
map.put(TAG_ADDRESS, address);
map.put(TAG_CELLPHONE, cellPhone);
jsonlist.add(map);
}
}
else{
String message ="No Donor Found";
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_FIRSTNAME, message);
map.put(TAG_MIDDLENAME, "");
map.put(TAG_LASTNAME ,"");
map.put(TAG_ADDRESS,"");
map.put(TAG_CELLPHONE, "");
jsonlist.add(map);
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
}

You can pass both values (comma separated or as array) in execute() method, and these values will be available in doInBackground() method.
Code:
// Calling AsyncTask in onCreate()
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_donor);
Intent i = getIntent();
if(i!=null) {
location = intent.getStringExtra("location");
bloodgroup = intent.getStringExtra("bloodgroup");
new ProgressTask(SearchDonor.this).execute(location,bloodgroup);
}
}
private class myAsyncTask extends AsyncTask<String, String, String> {
#Override
protected Void doInBackground(String...params)
{
// Getting values from params
String location = params[0];
String bloodGroup= params[1];
....
}
I did not run the code but it will give you the idea for doing. If you get any error post here.

adapter.notifyDataSetChanged() position inside activity code

In my activity (list view) with external adapter, I would need to refresh the data when the user goes back to the activity from another activity:
This is my current code:
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;
public class Empresas_MainActivity extends Activity {
// Declare Variables
private static final String TAG_NAME = "nombreCategoria";
private static final String TAG_ID = "idCategoria";
private String name = "Categoria";
private String id = "id";
JSONObject jsonobject;
JSONArray jsonarray;
ListView listview;
Empresas_ListViewAdapter adapter;
ProgressDialog mProgressDialog;
ArrayList<HashMap<String, String>> arraylist;
static String VALORACIONEMPRESA = "valoracionEmpresa";
static String NOMBREEMPRESA = "nombreEmpresa";
static String DIRECCIONEMPRESA = "direccionEmpresa";
static String STRIMAGEN = "strImagen";
static String DESCRIPCIONEMPRESA = "descripcionEmpresa";
static String TELEFONOEMPRESA = "telefonoEmpresa";
static String FACEBOOKEMPRESA = "facebookEmpresa";
static String EMAILEMPRESA = "emailEmpresa";
static String TEXTOOFERTA = "textoOferta";
static String HORARIOEMPRESA = "horarioEmpresa";
static String LATITUDEMPRESA = "latitudEmpresa";
static String LONGITUDEMPRESA = "longitudEmpresa";
static String IDEMPRESA = "idEmpresa";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.v("MVASCO", "context is null!");
// getting intent data
Intent in = getIntent();
// JSON node keys
// Get JSON values from previous intent
name = in.getStringExtra(TAG_NAME);
id = in.getStringExtra(TAG_ID);
this.setTitle(name);
// Get the view from listview_main.xml
setContentView(R.layout.empresas_listview_main);
// Execute DownloadJSON AsyncTask
new DownloadJSON().execute();
}
// DownloadJSON AsyncTask
private class DownloadJSON extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(Empresas_MainActivity.this);
// Set progressdialog title
mProgressDialog.setTitle("Vive Gran Canaria");
// Set progressdialog message
mProgressDialog.setMessage(name);
mProgressDialog.setIndeterminate(false);
// Show progressdialog
mProgressDialog.show();
}
#Override
protected Void doInBackground(Void... params) {
// Create an array
arraylist = new ArrayList<HashMap<String, String>>();
// Retrieve JSON Objects from the given URL address
jsonobject = JSONfunctions
.getJSONfromURL("http://xxxxxx/android_ofertaslist_todas.php?id="+id);
try {
// Locate the array name in JSON
jsonarray = jsonobject.getJSONArray("Categorias");
for (int i = 0; i < jsonarray.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
jsonobject = jsonarray.getJSONObject(i);
// Retrive JSON Objects
map.put("valoracionEmpresa", jsonobject.getString("valoracionEmpresa"));
map.put("nombreEmpresa", jsonobject.getString("nombreEmpresa"));
map.put("direccionEmpresa", jsonobject.getString("direccionEmpresa"));
map.put("strImagen", jsonobject.getString("strImagen"));
map.put("descripcionEmpresa", jsonobject.getString("descripcionEmpresa"));
map.put("telefonoEmpresa", jsonobject.getString("telefonoEmpresa"));
map.put("emailEmpresa", jsonobject.getString("emailEmpresa"));
map.put("textoOferta", jsonobject.getString("textoOferta"));
map.put("horarioEmpresa", jsonobject.getString("horarioEmpresa"));
map.put("facebookEmpresa", jsonobject.getString("facebookEmpresa"));
map.put("latitudEmpresa", jsonobject.getString("latitudEmpresa"));
map.put("longitudEmpresa", jsonobject.getString("longitudEmpresa"));
map.put("idEmpresa", jsonobject.getString("idEmpresa"));
// Set the JSON Objects into the array
arraylist.add(map);
}
} catch (JSONException e) {
Log.e("Error", e.getMessage());
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void args) {
// Locate the listview in listview_main.xml
listview = (ListView) findViewById(R.id.listview);
// Pass the results into ListViewAdapter.java
adapter = new Empresas_ListViewAdapter(Empresas_MainActivity.this, arraylist);
// Set the adapter to the ListView
listview.setAdapter(adapter);
adapter.notifyDataSetChanged();
// Close the progressdialog
mProgressDialog.dismiss();
}
}
}
I have put the call to adapter.notifyDataSetChanged() inside the postOnExecute method, but the values are not updated when coming back from another activity where some of the values may have changed. Where or how should I use adapter.notifyDataSetChanged();
Thank you.

You have to use either onResume. both functions are called on back pressed and when the activity starts for the first time.
so you should move the following:
new DownloadJSON().execute();
to
#Override
protected void onResume() {
// TODO Auto-generated method stub
super.onPause();
new DownloadJSON().execute();
}
you don't need to include notifyDataSetChanged() for this situation. I hope it helps you out

adapter = new Empresas_ListViewAdapter(Empresas_MainActivity.this, arraylist);
here you have to notify your adapter regarding data changes.
adapter.notifyDataSetChanged();
// first you have to notify adapter then Set the adapter to the ListView
listview.setAdapter(adapter);
rest of your code is fine according to me.

List view activity showing objects only the first time it is opened

In my Android app I have a list view activity showing MySQL objects downloaded from a web server via JSON.
I have detected following issue: the first time the activity is shown, the JSON objects are shown fine, but if the user goes back to the previous activity and then opens the list view activity again, any object is shown on the list and no error is thrown.
I need your help to solve this issue. Here is the activity code:
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ofertas_list extends ListActivity {
private ProgressDialog pDialog;
// JSON node keys
private static final String TAG_NAME = "nombreCategoria";
private static final String TAG_ID = "idCategoria";
private static final String TAG_CATEGORIAS = "Categorias";
// URL to get contacts JSON
private static String url = "http://xxxxxxxx/android_ofertaslist.php?id=";
// JSON Node names
private static final String TAG_NOMBREEMPRESA = "nombreEmpresa";
private static final String TAG_IDEMPRESA = "idEmpresa";
private static final String TAG_DESCRIPCIONEMPRESA = "descripcionEmpresa";
private static final String TAG_STRIMAGEN = "strImagen";
private static final String TAG_DIRECCIONEMPRESA = "direccionEmpresa";
private static final String TAG_TELEFONOEMPRESA = "telefonoEmpresa";
private static final String TAG_FACEBOOKEMPRESA = "facebookEmpresa";
private static final String TAG_EMAILEMPRESA = "emailEmpresa";
private static final String TAG_TEXTOOFERTA = "textoOferta";
private static final String TAG_HORARIOEMPRESA = "horarioEmpresa";
private static final String TAG_CATEGORIAEMPRESA = "categoriaEmpresa";
private static final String TAG_LATITUDEMPRESA = "latitudEmpresa";
private static final String TAG_LONGITUDEMPRESA = "longitudEmpresa";
private static final String TAG_VALORACIONEMPRESA = "valoracionEmpresa";
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_categorias);
// getting intent data
Intent in = getIntent();
// JSON node keys
// Get JSON values from previous intent
String name = in.getStringExtra(TAG_NAME);
String email = in.getStringExtra(TAG_ID);
// URL to get contacts JSON
this.url = url+email;
this.setTitle(name);
contactList = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
//cambiar por los nuevos campos
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String cost = ((TextView) view.findViewById(R.id.email))
.getText().toString();
//Starting single contact activity
//cambiar por los nuevos campos
Intent in = new Intent(getApplicationContext(),
SingleContactActivity.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_ID, cost);
startActivity(in);
}
});
// Calling async task to get json
new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(ofertas_list.this);
pDialog.setMessage("Cargando datos...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CATEGORIAS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String nombreEmpresa = c.getString(TAG_NOMBREEMPRESA);
String descripcionEmpresa = c.getString(TAG_DESCRIPCIONEMPRESA);
String strImagen = c.getString(TAG_STRIMAGEN);
String direccionEmpresa = c.getString(TAG_DIRECCIONEMPRESA);
String telefonoEmpresa = c.getString(TAG_TELEFONOEMPRESA);
String facebookEmpresa = c.getString(TAG_FACEBOOKEMPRESA);
String emailEmpresa = c.getString(TAG_EMAILEMPRESA);
String textoOferta = c.getString(TAG_TEXTOOFERTA);
String horarioEmpresa = c.getString(TAG_HORARIOEMPRESA);
String categoriaEmpresa = c.getString(TAG_CATEGORIAEMPRESA);
String valoracionEmpresa = c.getString(TAG_VALORACIONEMPRESA);
String latitudEmpresa = c.getString(TAG_LATITUDEMPRESA);
String longitudEmpresa = c.getString(TAG_LONGITUDEMPRESA);
String idEmpresa = c.getString(TAG_IDEMPRESA);
// Phone node is JSON Object
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_IDEMPRESA, idEmpresa);
contact.put(TAG_NOMBREEMPRESA, nombreEmpresa);
contact.put(TAG_DESCRIPCIONEMPRESA,descripcionEmpresa);
contact.put(TAG_STRIMAGEN,strImagen);
contact.put(TAG_DIRECCIONEMPRESA,direccionEmpresa);
contact.put(TAG_TELEFONOEMPRESA,telefonoEmpresa);
contact.put(TAG_FACEBOOKEMPRESA,facebookEmpresa);
contact.put(TAG_EMAILEMPRESA,emailEmpresa);
contact.put(TAG_TEXTOOFERTA,textoOferta);
contact.put(TAG_HORARIOEMPRESA,horarioEmpresa);
contact.put(TAG_CATEGORIAEMPRESA,categoriaEmpresa);
contact.put(TAG_VALORACIONEMPRESA,valoracionEmpresa);
contact.put(TAG_LATITUDEMPRESA,latitudEmpresa);
contact.put(TAG_LONGITUDEMPRESA,longitudEmpresa);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
ofertas_list.this, contactList,
R.layout.list_item_ofertas, new String[] { TAG_NOMBREEMPRESA, TAG_DIRECCIONEMPRESA}, new int[] { R.id.name,
R.id.email });
setListAdapter(adapter);
}
}
}
UPDATED CODE:
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ofertas_list extends ListActivity {
private ProgressDialog pDialog;
// JSON node keys
private static final String TAG_NAME = "nombreCategoria";
private static final String TAG_ID = "idCategoria";
private static final String TAG_CATEGORIAS = "Categorias";
// URL to get contacts JSON
private static String url = "http://xxxxxxx/android_ofertaslist.php?id=";
// URL to get contacts JSON
// private static String url = "http://mujercanariasigloxxi.appgestion.eu/app_php_files/android_ofertaslist.php";
// JSON Node names
private static final String TAG_NOMBREEMPRESA = "nombreEmpresa";
private static final String TAG_IDEMPRESA = "idEmpresa";
private static final String TAG_DESCRIPCIONEMPRESA = "descripcionEmpresa";
private static final String TAG_STRIMAGEN = "strImagen";
private static final String TAG_DIRECCIONEMPRESA = "direccionEmpresa";
private static final String TAG_TELEFONOEMPRESA = "telefonoEmpresa";
private static final String TAG_FACEBOOKEMPRESA = "facebookEmpresa";
private static final String TAG_EMAILEMPRESA = "emailEmpresa";
private static final String TAG_TEXTOOFERTA = "textoOferta";
private static final String TAG_HORARIOEMPRESA = "horarioEmpresa";
private static final String TAG_CATEGORIAEMPRESA = "categoriaEmpresa";
private static final String TAG_LATITUDEMPRESA = "latitudEmpresa";
private static final String TAG_LONGITUDEMPRESA = "longitudEmpresa";
private static final String TAG_VALORACIONEMPRESA = "valoracionEmpresa";
#Override
public void onResume(){
super.onResume();
new GetContacts().execute();
}
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_categorias);
// getting intent data
Intent in = getIntent();
// JSON node keys
// Get JSON values from previous intent
String name = in.getStringExtra(TAG_NAME);
String email = in.getStringExtra(TAG_ID);
// URL to get contacts JSON
this.url = url+email;
this.setTitle(name);
contactList = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
//cambiar por los nuevos campos
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String cost = ((TextView) view.findViewById(R.id.email))
.getText().toString();
//Starting single contact activity
//cambiar por los nuevos campos
Intent in = new Intent(getApplicationContext(),
SingleContactActivity.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_ID, cost);
startActivity(in);
}
});
// Calling async task to get json
new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(ofertas_list.this);
pDialog.setMessage("Cargando datos...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CATEGORIAS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String nombreEmpresa = c.getString(TAG_NOMBREEMPRESA);
String descripcionEmpresa = c.getString(TAG_DESCRIPCIONEMPRESA);
String strImagen = c.getString(TAG_STRIMAGEN);
String direccionEmpresa = c.getString(TAG_DIRECCIONEMPRESA);
String telefonoEmpresa = c.getString(TAG_TELEFONOEMPRESA);
String facebookEmpresa = c.getString(TAG_FACEBOOKEMPRESA);
String emailEmpresa = c.getString(TAG_EMAILEMPRESA);
String textoOferta = c.getString(TAG_TEXTOOFERTA);
String horarioEmpresa = c.getString(TAG_HORARIOEMPRESA);
String categoriaEmpresa = c.getString(TAG_CATEGORIAEMPRESA);
String valoracionEmpresa = c.getString(TAG_VALORACIONEMPRESA);
String latitudEmpresa = c.getString(TAG_LATITUDEMPRESA);
String longitudEmpresa = c.getString(TAG_LONGITUDEMPRESA);
String idEmpresa = c.getString(TAG_IDEMPRESA);
// Phone node is JSON Object
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_IDEMPRESA, idEmpresa);
contact.put(TAG_NOMBREEMPRESA, nombreEmpresa);
contact.put(TAG_DESCRIPCIONEMPRESA,descripcionEmpresa);
contact.put(TAG_STRIMAGEN,strImagen);
contact.put(TAG_DIRECCIONEMPRESA,direccionEmpresa);
contact.put(TAG_TELEFONOEMPRESA,telefonoEmpresa);
contact.put(TAG_FACEBOOKEMPRESA,facebookEmpresa);
contact.put(TAG_EMAILEMPRESA,emailEmpresa);
contact.put(TAG_TEXTOOFERTA,textoOferta);
contact.put(TAG_HORARIOEMPRESA,horarioEmpresa);
contact.put(TAG_CATEGORIAEMPRESA,categoriaEmpresa);
contact.put(TAG_VALORACIONEMPRESA,valoracionEmpresa);
contact.put(TAG_LATITUDEMPRESA,latitudEmpresa);
contact.put(TAG_LONGITUDEMPRESA,longitudEmpresa);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
ofertas_list.this, contactList,
R.layout.list_item_ofertas, new String[] { TAG_NOMBREEMPRESA, TAG_DIRECCIONEMPRESA}, new int[] { R.id.name,
R.id.email });
setListAdapter(adapter);
}
}
}

You should probably perform the "new GetContacts().execute();" call in onResume(). See the Android documentation to get more familiar with the Android Activity lifecyle.
onCreate() is only called when the Activity is created. In your testing, the Activity is probably usually still alive, so onCreate() will not always be called when re-entering the Activity.

Put your new GetContacts().execute() in onResume() method.
onCreate() is called when you start Activity for the first time. If you leave activity, without killing it, and come back, your app goes thru onStart() ->onResume()`
Put onResume right before onCreate and remove new GetContacts().execute(); from onCreate().
...
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
#Override
public void onResume(){
super.onResume();
new GetContacts().execute();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_categorias);
...

onResume() method on list view activity

I am working trying to solve an issue on an activity, but I am not able to find the reason for the behaviour.
I have a list view activity (Activity A), if the app user taps on a list row, a second list view activity (Activity B) is shown and all expected list objects are on the list.
Then, if the user navigates from activity B back to activity A, and selects the same or another row, then activity B is shown again, but none object is shown on the list.
I was told by another SO user to include a onResume method. I have done it, but the issue is not solved.
Here you have the activity B code:
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class ofertas_list extends ListActivity {
private ProgressDialog pDialog;
// JSON node keys
private static final String TAG_NAME = "nombreCategoria";
private static final String TAG_ID = "idCategoria";
private static final String TAG_CATEGORIAS = "Categorias";
// URL to get contacts JSON
private static String url = "http://xxxxx/android_ofertaslist.php?id=";
// JSON Node names
private static final String TAG_NOMBREEMPRESA = "nombreEmpresa";
private static final String TAG_IDEMPRESA = "idEmpresa";
private static final String TAG_DESCRIPCIONEMPRESA = "descripcionEmpresa";
private static final String TAG_STRIMAGEN = "strImagen";
private static final String TAG_DIRECCIONEMPRESA = "direccionEmpresa";
private static final String TAG_TELEFONOEMPRESA = "telefonoEmpresa";
private static final String TAG_FACEBOOKEMPRESA = "facebookEmpresa";
private static final String TAG_EMAILEMPRESA = "emailEmpresa";
private static final String TAG_TEXTOOFERTA = "textoOferta";
private static final String TAG_HORARIOEMPRESA = "horarioEmpresa";
private static final String TAG_CATEGORIAEMPRESA = "categoriaEmpresa";
private static final String TAG_LATITUDEMPRESA = "latitudEmpresa";
private static final String TAG_LONGITUDEMPRESA = "longitudEmpresa";
private static final String TAG_VALORACIONEMPRESA = "valoracionEmpresa";
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
#Override
public void onResume(){
super.onResume();
new GetContacts().execute();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_categorias);
// getting intent data
Intent in = getIntent();
// JSON node keys
// Get JSON values from previous intent
String name = in.getStringExtra(TAG_NAME);
String email = in.getStringExtra(TAG_ID);
// URL to get contacts JSON
this.url = url+email;
this.setTitle(name);
contactList = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
//cambiar por los nuevos campos
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String cost = ((TextView) view.findViewById(R.id.email))
.getText().toString();
//Starting single contact activity
//cambiar por los nuevos campos
Intent in = new Intent(getApplicationContext(),
SingleContactActivity.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_ID, cost);
startActivity(in);
}
});
// Calling async task to get json
//new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(ofertas_list.this);
pDialog.setMessage("Cargando datos...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CATEGORIAS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String nombreEmpresa = c.getString(TAG_NOMBREEMPRESA);
String descripcionEmpresa = c.getString(TAG_DESCRIPCIONEMPRESA);
String strImagen = c.getString(TAG_STRIMAGEN);
String direccionEmpresa = c.getString(TAG_DIRECCIONEMPRESA);
String telefonoEmpresa = c.getString(TAG_TELEFONOEMPRESA);
String facebookEmpresa = c.getString(TAG_FACEBOOKEMPRESA);
String emailEmpresa = c.getString(TAG_EMAILEMPRESA);
String textoOferta = c.getString(TAG_TEXTOOFERTA);
String horarioEmpresa = c.getString(TAG_HORARIOEMPRESA);
String categoriaEmpresa = c.getString(TAG_CATEGORIAEMPRESA);
String valoracionEmpresa = c.getString(TAG_VALORACIONEMPRESA);
String latitudEmpresa = c.getString(TAG_LATITUDEMPRESA);
String longitudEmpresa = c.getString(TAG_LONGITUDEMPRESA);
String idEmpresa = c.getString(TAG_IDEMPRESA);
// Phone node is JSON Object
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_IDEMPRESA, idEmpresa);
contact.put(TAG_NOMBREEMPRESA, nombreEmpresa);
contact.put(TAG_DESCRIPCIONEMPRESA,descripcionEmpresa);
contact.put(TAG_STRIMAGEN,strImagen);
contact.put(TAG_DIRECCIONEMPRESA,direccionEmpresa);
contact.put(TAG_TELEFONOEMPRESA,telefonoEmpresa);
contact.put(TAG_FACEBOOKEMPRESA,facebookEmpresa);
contact.put(TAG_EMAILEMPRESA,emailEmpresa);
contact.put(TAG_TEXTOOFERTA,textoOferta);
contact.put(TAG_HORARIOEMPRESA,horarioEmpresa);
contact.put(TAG_CATEGORIAEMPRESA,categoriaEmpresa);
contact.put(TAG_VALORACIONEMPRESA,valoracionEmpresa);
contact.put(TAG_LATITUDEMPRESA,latitudEmpresa);
contact.put(TAG_LONGITUDEMPRESA,longitudEmpresa);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
ofertas_list.this, contactList,
R.layout.list_item_ofertas, new String[] { TAG_NOMBREEMPRESA, TAG_DIRECCIONEMPRESA}, new int[] { R.id.name,
R.id.email });
setListAdapter(adapter);
}
}
}
I am trying to solve the issue for two days but still no success. Please you are kindly requested to give me an advice on how to solve the issue.
CODE FOR ACTIVITY A:
import java.util.ArrayList;
import java.util.HashMap;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class categorias_list extends ListActivity {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://XXXX/android_categoriaslist.php";
// JSON Node names
private static final String TAG_NAME = "nombreCategoria";
private static final String TAG_ID = "idCategoria";
private static final String TAG_CATEGORIAS = "Categorias";
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_categorias);
contactList = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
// Listview on item click listener
lv.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name))
.getText().toString();
String cost = ((TextView) view.findViewById(R.id.email))
.getText().toString();
//Starting single contact activity
Intent in = new Intent(getApplicationContext(),
ofertas_list.class);
in.putExtra(TAG_NAME, name);
in.putExtra(TAG_ID, cost);
startActivity(in);
}
});
// Calling async task to get json
new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(categorias_list.this);
pDialog.setMessage("Cargando datos...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
contacts = jsonObj.getJSONArray(TAG_CATEGORIAS);
// looping through All Contacts
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
// Phone node is JSON Object
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_ID, id);
contact.put(TAG_NAME, name);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
categorias_list.this, contactList,
R.layout.list_item, new String[] { TAG_NAME, TAG_ID}, new int[] { R.id.name,
R.id.email });
setListAdapter(adapter);
}
}
}
CODE FOR SERVICE HANDLER:
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.client.utils.URLEncodedUtils;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;
public class ServiceHandler {
static String response = null;
public final static int GET = 1;
public final static int POST = 2;
public ServiceHandler() {
}
/**
* Making service call
* #url - url to make request
* #method - http request method
* */
public String makeServiceCall(String url, int method) {
return this.makeServiceCall(url, method, null);
}
/**
* Making service call
* #url - url to make request
* #method - http request method
* #params - http request params
* */
public String makeServiceCall(String url, int method,
List<NameValuePair> params) {
try {
// http client
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpEntity httpEntity = null;
HttpResponse httpResponse = null;
// Checking http request method type
if (method == POST) {
HttpPost httpPost = new HttpPost(url);
// adding post params
if (params != null) {
httpPost.setEntity(new UrlEncodedFormEntity(params));
}
httpResponse = httpClient.execute(httpPost);
} else if (method == GET) {
// appending params to url
if (params != null) {
String paramString = URLEncodedUtils
.format(params, "utf-8");
url += "?" + paramString;
}
HttpGet httpGet = new HttpGet(url);
httpResponse = httpClient.execute(httpGet);
}
httpEntity = httpResponse.getEntity();
response = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return response;
}
}

You have to need maintain arraylist globalaly use
Adapter.notifyDatasetChanged(); for updating the list:

List view can be updated by updating your array adapt
YourArrayAdapterName.notifyDataSetChanged;
Above code must be added in your Activities onResume Method, Which is your firt activity for the List
Example:
#Override
protected void onResume() {
super.onResume();
yourAdapterName.notifyDataSetChanged();
// do other stuffs here.
}

My aSyncTask is not working

my asynctask is not working. The dialog wont dismiss and the list is not being updated (i think because onPostExecute is not being called).I googled it, but without result.
package com.example.whs;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class Albums extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
// Array for the list
ArrayList<HashMap<String, String>> itemList;
// url to get the items
private static String url_all_products = "<my url here>";
// JSON variables
private static final String TAG_SUCCESS = "success";
private static final String TAG_MESSAGE = "message";
private static final String TAG_ITEMS = "items";
private static final String TAG_NAME = "name";
private static final String TAG_ID = "id";
private static final String TAG_USERNAME = "username";
//JSON array
JSONArray items = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_albums);
// HashMap for the items
itemList = new ArrayList<HashMap<String, String>>();
// Loading the items on the background
new LoadAllItems().execute();
// Get list-view
ListView lv = getListView();
// On item click
lv.setOnItemClickListener(new OnItemClickListener(){
public void onItemClick(AdapterView<?> parent, View view, int position, long id){
//do
}
});
}
// class for loading all items
class LoadAllItems extends AsyncTask<String, String, String> {
// Before
#Override
protected void onPreExecute(){
super.onPreExecute();
pDialog = new ProgressDialog(Albums.this);
pDialog.setMessage("Albums laden...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
// Get the products
#Override
protected String doInBackground(String... params) {
// Build Parameters
List<NameValuePair> params1 = new ArrayList<NameValuePair>();
//Get the JSON string
JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params1);
// Check for response
Log.d("All Items: ", json.toString());
try {
// check for success tag
int success = json.getInt(TAG_SUCCESS);
if(success == 1) {
// found the items
items = json.getJSONArray(TAG_ITEMS);
// loop through the items
for (int i = 0; items.length() > i; i++){
// Get the item in variable c
JSONObject c = items.getJSONObject(i);
// Store in a variable
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String username = c.getString(TAG_USERNAME);
if(username == ""){
username = "onbekend";
}
// Create the HashMap
HashMap<String, String> map = new HashMap<String, String>();
// add it
map.put(TAG_ID, id);
map.put(TAG_USERNAME, username);
map.put(TAG_NAME, name);
// to arraylist
itemList.add(map);
}
}else{
// nothing found
Intent i = new Intent(getApplicationContext(), Index.class);
// close the previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e){
e.printStackTrace();
}
return null;
}
}
protected void onPostExecute(String result){
// dismiss dialog
pDialog.dismiss();
runOnUiThread(new Runnable(){
public void run(){
// Add adapter to the list
MenuAdapter adapter = new MenuAdapter(Albums.this, itemList);
ListView list = (ListView)findViewById(R.id.list);
list.setAdapter(adapter);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.albums, menu);
return true;
}
}
the loop is working correctly.
How to fix this?

1) you are trying to start an activity within the background thread, don't do this.
2) you are probably getting a json exception, just log more things so you can see what is happening
these may be why it never reaches onPostExecute

you can not perform UI related action in doInBackGround(), like you are strating a new activity in doInBaclground,
Intent i = new Intent(getApplicationContext(), Index.class);
// close the previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);