Develop Reference

After pressing back button, previous activity (listview) is emtpty

In my android project i have a listview with items loaded from an online database. When i click on an item i go to another class where i can delete or update it. My problem is that when i press the back button, my listview is empty. I tried onBackPressed with intent to go to previous activity but it is empty again. I want to reload my listview when from a clicked item i press the back button. Below is my code.
The listview:
public class AllStudents extends AppCompatActivity {
ListView StudentListView;
ProgressBar progressBar;
String HttpUrl = "http://sissy-nickels.000webhostapp.com/AllStudentData.php";
List<String> IdList = new ArrayList<>();
String LessonName;
HttpParse httpParse = new HttpParse();
ProgressDialog pDialog;
String FinalJSonObject;
HashMap<String,String> ResultHash = new HashMap<>();
String ParseResult ;
List<Student> studentList;
EditText search;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_allstudents);
StudentListView = (ListView)findViewById(R.id.listview2);
progressBar = (ProgressBar)findViewById(R.id.progressBar);
LessonName = getIntent().getStringExtra("Lesson");
HttpWebCall(LessonName);
//Adding ListView Item click Listener.
StudentListView.setOnItemClickListener(new AdapterView.OnItemClickListener()
{
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
// TODO Auto-generated method stub
Intent intent = new Intent(AllStudents.this,SingleStudent.class);
// Sending ListView clicked value using intent.
intent.putExtra("ListViewValue", IdList.get(position).toString());
startActivity(intent);
//Finishing current activity after open next activity.
//finish();
}
});
search = (EditText)findViewById(R.id.search);
search.addTextChangedListener(new TextWatcher() {
#Override
public void beforeTextChanged (CharSequence s, int start, int count, int after) {
}
// when text is entered in search box, filter list by search text
#Override
public void onTextChanged(CharSequence cs, int start, int before, int count) {
filterStudents(cs);
}
#Override
public void afterTextChanged(Editable s) {
}
});
// check student's name whether contain text entered in search box
}
public void HttpWebCall(final String LessonName){
class HttpWebCallFunction extends AsyncTask<String,Void,String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = ProgressDialog.show(AllStudents.this,"Loading Data",null,true,true);
}
#Override
protected void onPostExecute(String httpResponseMsg) {
super.onPostExecute(httpResponseMsg);
pDialog.dismiss();
//Storing Complete JSon Object into String Variable.
FinalJSonObject = httpResponseMsg ;
//Parsing the Stored JSOn String to GetHttpResponse Method.
new GetHttpResponse(AllStudents.this).execute();
}
#Override
protected String doInBackground(String... params) {
ResultHash.put("LessonName",params[0]);
ParseResult = httpParse.postRequest(ResultHash, HttpUrl);
return ParseResult;
}
}
HttpWebCallFunction httpWebCallFunction = new HttpWebCallFunction();
httpWebCallFunction.execute(LessonName);
}
// JSON parse class started from here.
private class GetHttpResponse extends AsyncTask<Void, Void, Void>
{
public Context context;
public GetHttpResponse(Context context)
{
this.context = context;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... arg0)
{
try
{
if(FinalJSonObject != null)
{
JSONArray jsonArray = null;
try {
jsonArray = new JSONArray(FinalJSonObject);
JSONObject jsonObject;
Student student;
studentList = new ArrayList<Student>();
for(int i=0; i<jsonArray.length(); i++)
{
jsonObject = jsonArray.getJSONObject(i);
student = new Student();
// Adding Student Id TO IdList Array.
IdList.add(jsonObject.getString("id").toString());
//Adding Student Name.
student.StudentName = jsonObject.getString("Regnum").toString();
studentList.add(student);
}
}
catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result)
{
progressBar.setVisibility(View.GONE);
StudentListView.setVisibility(View.VISIBLE);
ListAdapter adapter = new ListAdapter(studentList, context);
StudentListView.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
}
private void filterStudents (CharSequence cs) {
List<Student> filteredList = new ArrayList<>();
if (TextUtils.isEmpty(cs)) {
// no text is entered for search, do nothing
return;
}
// build new student list which filtered by search text.
for (Student student : studentList) {
if (student.StudentName.contains(cs)) {
filteredList.add(student);
}
}
// show filtered list in listview
ListAdapter adapter = new ListAdapter(filteredList, this);
StudentListView.setAdapter(adapter);
adapter.notifyDataSetChanged();
}}
And the code from item click:
public class SingleStudent extends AppCompatActivity {
HttpParse httpParse = new HttpParse();
ProgressDialog pDialog;
// Http Url For Filter Student Data from Id Sent from previous activity.
String HttpURL = "http://sissy-nickels.000webhostapp.com/FilterStudentData.php";
// Http URL for delete Already Open Student Record.
String HttpUrlDeleteRecord = "http://sissy-nickels.000webhostapp.com/DeleteStudent.php";
String finalResult ;
HashMap<String,String> hashMap = new HashMap<>();
String ParseResult ;
HashMap<String,String> ResultHash = new HashMap<>();
String FinalJSonObject ;
TextView NAME,SURNAME,DEPT,REGNUM,GRADE;
String NameHolder, SurnameHolder, DeptHolder, RegnumHolder, GradeHolder;
Button UpdateButton, DeleteButton;
String TempItem;
ProgressDialog progressDialog2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_singlestudent);
NAME = (TextView)findViewById(R.id.name);
SURNAME = (TextView)findViewById(R.id.surname);
DEPT = (TextView)findViewById(R.id.dept);
REGNUM = (TextView)findViewById(R.id.regnum);
GRADE = (TextView)findViewById(R.id.grade);
UpdateButton = (Button)findViewById(R.id.BDel);
DeleteButton = (Button)findViewById(R.id.BUp);
//Receiving the ListView Clicked item value send by previous activity.
TempItem = getIntent().getStringExtra("ListViewValue");
//Calling method to filter Student Record and open selected record.
HttpWebCall(TempItem);
UpdateButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(SingleStudent.this,StudentUpdate.class);
// Sending Student Id, Name, Number and Class to next UpdateActivity.
intent.putExtra("Id", TempItem);
intent.putExtra("name", NameHolder);
intent.putExtra("surname", SurnameHolder);
intent.putExtra("dept", DeptHolder);
intent.putExtra("regnum", RegnumHolder);
intent.putExtra("grade", GradeHolder);
startActivity(intent);
// Finishing current activity after opening next activity.
finish();
}
});
// Add Click listener on Delete button.
DeleteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// Calling Student delete method to delete current record using Student ID.
StudentDelete(TempItem);
}
});
}
// Method to Delete Student Record
public void StudentDelete(final String StudentID) {
class StudentDeleteClass extends AsyncTask<String, Void, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
progressDialog2 = ProgressDialog.show(SingleStudent.this, "Φόρτωση", null, true, true);
}
#Override
protected void onPostExecute(String httpResponseMsg) {
super.onPostExecute(httpResponseMsg);
progressDialog2.dismiss();
Toast.makeText(SingleStudent.this, httpResponseMsg.toString(), Toast.LENGTH_LONG).show();
finish();
}
#Override
protected String doInBackground(String... params) {
// Sending STUDENT id.
hashMap.put("StudentID", params[0]);
finalResult = httpParse.postRequest(hashMap, HttpUrlDeleteRecord);
return finalResult;
}
}
StudentDeleteClass studentDeleteClass = new StudentDeleteClass();
studentDeleteClass.execute(StudentID);
}
//Method to show current record Current Selected Record
public void HttpWebCall(final String PreviousListViewClickedItem){
class HttpWebCallFunction extends AsyncTask<String,Void,String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = ProgressDialog.show(SingleStudent.this,"Φόρτωση",null,true,true);
}
#Override
protected void onPostExecute(String httpResponseMsg) {
super.onPostExecute(httpResponseMsg);
pDialog.dismiss();
//Storing Complete JSon Object into String Variable.
FinalJSonObject = httpResponseMsg ;
//Parsing the Stored JSOn String to GetHttpResponse Method.
new GetHttpResponse(SingleStudent.this).execute();
}
#Override
protected String doInBackground(String... params) {
ResultHash.put("StudentID",params[0]);
ParseResult = httpParse.postRequest(ResultHash, HttpURL);
return ParseResult;
}
}
HttpWebCallFunction httpWebCallFunction = new HttpWebCallFunction();
httpWebCallFunction.execute(PreviousListViewClickedItem);
}
// Parsing Complete JSON Object.
private class GetHttpResponse extends AsyncTask<Void, Void, Void>
{
public Context context;
public GetHttpResponse(Context context)
{
this.context = context;
}
#Override
protected void onPreExecute()
{
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... arg0)
{
try
{
if(FinalJSonObject != null)
{
JSONArray jsonArray = null;
try {
jsonArray = new JSONArray(FinalJSonObject);
JSONObject jsonObject;
for(int i=0; i<jsonArray.length(); i++)
{
jsonObject = jsonArray.getJSONObject(i);
// Storing Student Name, Phone Number, Class into Variables.
NameHolder = jsonObject.getString("Name").toString() ;
SurnameHolder = jsonObject.getString("Surname").toString() ;
DeptHolder = jsonObject.getString("Dept").toString() ;
RegnumHolder = jsonObject.getString("Regnum").toString() ;
GradeHolder = jsonObject.getString("Grade").toString() ;
}
}
catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
catch (Exception e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result)
{
// Setting Student Name, Phone Number, Class into TextView after done all process .
NAME.setText(NameHolder);
SURNAME.setText(SurnameHolder);
DEPT.setText(DeptHolder);
REGNUM.setText(RegnumHolder);
GRADE.setText(GradeHolder);
}
}}
Than you in advance!

try this on AllStudents activity
#Override
protected void onResume() {
super.onResume();
if (studentList != null && studentList.size()>0) {
ListAdapter adapter = new ListAdapter(studentList, this);
StudentListView.setAdapter(adapter);
adapter.notifyDataSetChanged();
}
}
*Note
when you make a search you run the filterStudents() method
and replace the current list in the adapter
ListAdapter adapter = new ListAdapter(filteredList, this);
but make sure that if you search for nothing .. return the original list
ListAdapter adapter = new ListAdapter(studentList, this);
or you will get an empty list view

You should not recreate from secondActivity. You just finish it when your work is done in secondActivity. Which means, simply you have to do the below in your secondActivity.
#Override
public void onBackPressed() {
super.onBackPressed();
}

How to use listview from different xml layout file

I am working on android ListView and i am getting one issue.I created one list view into the XML file installation.xml and i want to use that list view into my Searchdata.java. so basically what i want that when i click on searchdata button than data is fetched from web service and after parsing, it will saved into the listview.and when i click on Installation View button than new window will be appear where i could see that list data.
SearchData.java
public class SearchData extends Activity {
EditText Keyword;
JSONParser jsonparser = new JSONParser();
ListView Datalist;
HorizontalScrollView VideoDatalist;
ArrayList<HashMap<String, String>> DataList;
ArrayList<HashMap<String, String>> VideoDataList;
JSONArray contacts = null;
private ProgressDialog pDialog;
ImageButton searchdata,InstallationView;
String Keyvalue = new String();
private static final String TAG_InnerText = "InnerText";
private static final String TAG_Title = "Title";
private static final String TAG_URL = "URL";
private static final String TAG_VIDEO_URL = "URL";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search_data);
InstallationView=(ImageButton)findViewById(R.id.InstallationView);
Keyword = (EditText) findViewById(R.id.KeyData);
Datalist=(ListView)findViewById(R.layout.activity_installation);
VideoDatalist=(HorizontalScrollView)findViewById(R.id.Horizontallist);
searchdata=(ImageButton)findViewById(R.id.searchicon);
String Keyvalue = new String();
DataList = new ArrayList<HashMap<String, String>>();
VideoDataList = new ArrayList<HashMap<String, String>>();
searchdata.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
new ReadData().execute();
}
});
InstallationView.setOnClickListener(new View.OnClickListener(){
public void onClick(View v)
{
startActivity(new Intent(SearchData.this, Installation.class));
}
});
}
public class ReadData extends AsyncTask<Void, Void, Void>
{
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(SearchData.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
protected Void doInBackground(Void... arg0) {
try{
Keyvalue=Keyword.getText().toString();
String Jsonstr = jsonparser.makeHttpRequest("http://10.47.93.26:8080/Search/api/Search/"+Keyvalue);
try {
if (Jsonstr != null) {
JSONArray jsonObj = new JSONArray (Jsonstr);
for (int i = 0; i < jsonObj.length(); i++) {
JSONObject c = jsonObj.getJSONObject(i);
String name = c.optString(TAG_Title);
String url = c.optString(TAG_URL);
HashMap<String, String> info = new HashMap<String, String>();
if( !name.isEmpty() )
{
info.put(TAG_Title, name);
}
else
{
info.put(TAG_Title,"User Manual");
}
if(url.contains("youtube"))
{
info.put(TAG_URL, url);
VideoDataList.add(info);
}
else
{
info.put(TAG_URL, url);
DataList.add(info);
}
}
}
else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
}
catch (JSONException e) {
e.printStackTrace();
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
if (pDialog.isShowing())
pDialog.dismiss();
SimpleAdapter adapter = new SimpleAdapter(
SearchData.this, DataList,
R.layout.list_item, new String[]
{
TAG_Title
}, new int[] {
R.id.InnerText });
Datalist.setAdapter(adapter);
}
}
}
web service running and parsing code is running correctly. i am getting error at post method,so can you help me on this.
Error

Call your Installation activity in onClick() method:
And pass your ArrayList data through intent,
InstallationView.setOnClickListener(new View.OnClickListener(){
public void onClick(View v)
{
Intent intent= new Intent(SearchData.this, Installation.class);
intent.putParcelableArrayListExtra("HASH_MAP",DataList);
startActivity(intent);
}
});
In your Installation activity class,set the view in onCreate() and initialize listview from xml file:
setContentView(R.layout.activity_installation);
ListView listView = (ListView)findViwById(R.id.listview);
And try to get the data from intent:
ArrayList<HashMap<String,String>> hashmap_dataList = getIntent.getParcelableArrayListExtra("HASH_MAP");
then do whatever you want with listview and hashmap.

In the onCreate(...) method of your SearchData Activity, the following can never work and will always return 'null' (hence your NullPointerException)...
Datalist=(ListView)findViewById(R.layout.activity_installation);
Calling findViewById(...) will only work for any UI elements which have been inflated when you called setContentView(...). In this case you used R.layout.activity_search_data for your layout file which doesn't contain a ListView with an id of R.layout.activity_installation which is, by the way, a resource id of a layout file and not a resource id of a UI element.
The only way you can do what you need is to put your data as an extra into the Intent you use when you call...
startActivity(new Intent(SearchData.this, Installation.class));
...when the Installation Activity is created it will then need to get the data and create its own adapter.
EDIT: HashMap is Serializable and can be passed as an Intent extra. Pass your DataList HashMap as follows...
Intent i = new Intent(SearchData.this, Installation.class);
i.putExtra("data_list", DataList);
startActivity(i);
In the Installation Activity you can then use...
getIntent().getSerializableExtra("data_list");

AsyncTask getting called everytime

I have a navigation drawer containing 2 items. Now in my first item click, I load data using asynctask and the loaded data is populated in a listview in the corresponding fragment. Now when I switch to 2nd item, again I load data using AsyncTask for the 2nd fragment and show it in in listview.
Now the problem starts. When I go back to the 1st fragment, my
asyncTask is called again and the data is again fetched from the
server, I want to prevent this and load my data directly if it has
been already loaded once.
Please suggest
P.S - Please ask for the code if anyone needs it.
USERPAYFRAGMENT
public class UserPay extends Fragment {
ProgressDialog prg;
Properties prop;
private PrefSingleton mMyPreferences;
private JSONParser jsonParser = new JSONParser();
ArrayList<HashMap<String, String>> RequestList;
HashMap<String, String> map;
UserAdapter req_adp;
ListView req;
private boolean flag;
#Override
public void onAttach(Activity activity) {
// TODO Auto-generated method stub
super.onAttach(activity);
Toast.makeText(getActivity(), "ATTACHED", 1000).show();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
Toast.makeText(getActivity(), "CREATE", 1000).show();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.user_pay, container, false);
initViews(rootView);
Toast.makeText(getActivity(), "ONCREATEVIEW", 1000).show();
return rootView;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Toast.makeText(getActivity(), "ONACTIVITYCREATED", 1000).show();
mMyPreferences = PrefSingleton.getInstance();
mMyPreferences.Initialize(getActivity());
RequestList = new ArrayList<HashMap<String, String>>();
Resources resources = this.getResources();
AssetManager assetManager = resources.getAssets();
try {
InputStream inputStream = assetManager.open("jsonURL.properties");
prop = new Properties();
prop.load(inputStream);
} catch (IOException e) {
System.err.println("Failed to open jsonURL property file");
e.printStackTrace();
}
req_adp = new UserAdapter(getActivity(), RequestList);
req.setAdapter(req_adp);
if (!flag) {
new GetRequests().execute();
} else {
}
}
#Override
public void onStart() {
// TODO Auto-generated method stub
super.onStart();
Toast.makeText(getActivity(), "ONSTART", 1000).show();
}
#Override
public void onResume() {
// TODO Auto-generated method stub
super.onResume();
Toast.makeText(getActivity(), "ONRESUME", 1000).show();
}
private void initViews(View v) {
req = (ListView) v.findViewById(R.id.req_list);
}
private class GetRequests extends AsyncTask<Void, Void, Integer> {
#Override
protected void onPreExecute() {
super.onPreExecute();
prg = new ProgressDialog(getActivity());
prg.setIndeterminate(true);
prg.setMessage("Fetching Pending Requests...");
prg.setCanceledOnTouchOutside(false);
prg.show();
}
#Override
protected Integer doInBackground(Void... params) {
List<NameValuePair> params1 = new ArrayList<NameValuePair>();
params1.add(new BasicNameValuePair("userID", mMyPreferences
.getPreference("LoginId")));
String error_code = null;
Log.e("URL ", "is" + prop.getProperty("GET_REQUESTS_URL"));
try {
// getting JSON string from URL
JSONObject json = jsonParser.makeHttpRequest(
Appconstant.GET_REQUESTS_URL, "POST", params1);
// Check your log cat for JSON response
Log.d("Inbox JSON: ", json.toString());
JSONObject jsonObj = json.getJSONObject("data");
error_code = jsonObj.getString("Error_Code");
RequestList.clear();
if ("1".equals(error_code)) {
JSONArray jArray = jsonObj.getJSONArray("result");
for (int i = 0; i < jArray.length(); i++) {
map = new HashMap<String, String>();
JSONObject jsonObj1 = jArray.getJSONObject(i);
String FBankId = jsonObj1
.getString("payment_from_bank_id");
String DestBankId = jsonObj1
.getString("payment_to_bank_id");
String FBank = jsonObj1.getString("fBank");
String TBank = jsonObj1.getString("tBank");
String reason = jsonObj1.getString("payment_reason");
String amt = jsonObj1.getString("amount");
String p_type = jsonObj1.getString("payment_type");
String status = jsonObj1.getString("status");
String r_date = jsonObj1
.getString("request_created_date");
map.put("FBankId", FBankId);
map.put("TBankId", DestBankId);
map.put("SourceBank", FBank);
map.put("DestBank", TBank);
map.put("ReqDate", r_date);
map.put("PayReason", reason);
map.put("Amt", amt);
map.put("PayType", p_type);
map.put("Status", status);
if (status.equals("pending")) {
if (p_type.equals("cheque")
|| p_type.equals("Net Banking")) {
RequestList.add(map);
}
}
}
}
} catch (JSONException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return Integer.parseInt(error_code);
}
#Override
protected void onPostExecute(Integer result) {
super.onPostExecute(result);
if (prg.isShowing()) {
prg.cancel();
}
if (result == 2) {
Toast.makeText(getActivity(),
"No User Request Details Available.Please Try Again",
Toast.LENGTH_SHORT).show();
}
req_adp.notifyDataSetChanged();
flag = true;
}
}
#Override
public void onPause() {
// TODO Auto-generated method stub
super.onPause();
Toast.makeText(getActivity(), "ONPAUSE",1000).show();
}
#Override
public void onStop() {
// TODO Auto-generated method stub
super.onStop();
Toast.makeText(getActivity(), "ONSTOP", 1000).show();
}
#Override
public void onDestroyView() {
// TODO Auto-generated method stub
super.onDestroyView();
Toast.makeText(getActivity(), "ONDESTROYVIEW", 1000).show();
}
#Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
Toast.makeText(getActivity(), "ONDESTROY", 1000).show();
}
#Override
public void onDetach() {
// TODO Auto-generated method stub
super.onDetach();
Toast.makeText(getActivity(), "ONDETACH", 1000).show();
}
}

There are 2 ways to solve
1 - store the data locally and make use stored data based on appropriate condition checks
2 - If your app is based on this 2 fragments, just create the instance of these fragments and store in in member variable of parent activity. do not give chance to recreate again and again

Android parsed json data and add a search functionality

Sorry for my bad english.I am new to android and i parsed json data into listview,now i want to put on him a search functionality,but i have a problem,when i entered a words in edittext,then in the listview my items are duplicated,and items has been increases,look my code and screen shots.Thanks in advance and any help will be much appreciated.
My Artist Activity:
public class Artists extends Activity {
// Connection detector
ConnectionDetector cd;
// Alert dialog manager
AlertDialogManager alert = new AlertDialogManager();
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jsonParser = new JSONParser();
// This is not using now if you want you can remove its all references :)
ArrayList<HashMap<String, String>> albumsList;
ArrayList<AdapterDTOArtist> mAdapterDTOs = null;
private LazyAdapterArtist mLazyAdatper = null;
private ArrayList<String> array_sort = new ArrayList<String>();
int textlength = 0;
// albums JSONArray
JSONArray albums = null;
LinearLayout ll_artists_chart;
LinearLayout ll_artists_newrelease;
private EditText etSearch;
private static String URL_ALBUMS = "http://triplevmusic.com/dev/webservice/index.php?op=fetch_artists.json";
// JSON Node names
private static final String TAG_CONTACTS = "data";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private ListView lv = null;
EditText et_artists_searchWord;
// contacts JSONArray
JSONArray contacts = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.artists);
lv = (ListView) findViewById(R.id.artist_main_list_id);
cd = new ConnectionDetector(getApplicationContext());
// Check for internet connection
if (!cd.isConnectingToInternet()) {
// Internet Connection is not present
alert.showAlertDialog(Artists.this,
"Internet Connection Error",
"Please connect to working Internet connection", false);
// stop executing code by return
return;
}
// Hashmap for ListView
albumsList = new ArrayList<HashMap<String, String>>();
mAdapterDTOs = new ArrayList<AdapterDTOArtist>();
// Loading Albums JSON in Background Thread
new LoadAlbums().execute();
// get listview
/**
* Listview item click listener TrackListActivity will be lauched by
* passing album id
* */
lv.setOnItemClickListener(new android.widget.AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View view, int arg2,
long arg3) {
// on selecting a single album
}
});
ll_artists_chart = (LinearLayout) findViewById(R.id.ll_artists_chart);
ll_artists_newrelease = (LinearLayout) findViewById(R.id.ll_artists_newrelease);
et_artists_searchWord = (EditText) findViewById(R.id.et_artists_searchWord);
et_artists_searchWord.addTextChangedListener(new TextWatcher() {
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// TODO Auto-generated method stub
// ((Filterable) Artists.this.mAdapterDTOs).getFilter().filter(s);
List<AdapterDTOArtist> list = filter(s.toString(),mAdapterDTOs, true);
mAdapterDTOs.addAll(list);
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
// TODO Auto-generated method stub
}
#Override
public void afterTextChanged(Editable s) {
// TODO Auto-generated method stub
}
});
ll_artists_chart.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getBaseContext(), ChartActivity.class);
startActivity(intent);
// finish();
}
});
ll_artists_newrelease.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent = new Intent(getBaseContext(), NewReleases.class);
startActivity(intent);
//finish();
}
});
}
/**
* Background Async Task to Load all Albums by making http request
* */
class LoadAlbums extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(Artists.this);
pDialog.setMessage("Listing Artists ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting Albums JSON
* */
protected String doInBackground(String... args) {
// Building Parameters
//List<NameValuePair> params = new ArrayList<NameValuePair>();
ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>();
// Creating JSON Parser instance
JSONParser jParser = new JSONParser();
JSONObject json = jParser.getJSONFromUrl(URL_ALBUMS);
// getting JSON string from URL
//String json = jsonParser.makeHttpRequest(URL_ALBUMS, "GET", params);
// Check your log cat for JSON reponse
Log.i("Albums JSON: ", "> " + json);
try {
//albums = new JSONArray(json);
albums = json.getJSONArray(TAG_CONTACTS);
if (albums != null) {
// looping through All albums
for (int i = 0; i < albums.length(); i++) {
JSONObject c = albums.getJSONObject(i);
// Storing each json item values in variable
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
/*String EateryThmbnailUrl = c
.getString(TAG_THMBNAIL_URL);*/
// ~\/Uploads\/EateryImages\/\/7\/41283f1f-8e6f-42d4-b3c1-01f990efb428.gif
/*EateryThmbnailUrl = HOST_URL
+ EateryThmbnailUrl.replace("~", "");*/
AdapterDTOArtist adapterDTO = new AdapterDTOArtist();
adapterDTO.setmTag_Id(id);
adapterDTO.setmTag_Name(name);
// adapterDTO.setmImage_URL(EateryThmbnailUrl);
mAdapterDTOs.add(adapterDTO);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
HashMap<String, Integer> map1 = new HashMap<String, Integer>();
// adding each child node to HashMap key => value
map.put(TAG_ID, id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
albumsList.add(map);
}
} else {
Log.d("Albums: ", "null");
}
} 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 albums
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
public void run() {
/**
* Updating parsed JSON data into ListView
* */
// updating listview
mLazyAdatper = new LazyAdapterArtist(Artists.this,
mAdapterDTOs);
lv.setAdapter(mLazyAdatper);
// mLazyAdatper.setDataSet(mAdapterDTOs);
}
});
}
}
public static List<AdapterDTOArtist> filter(String string,
Iterable<AdapterDTOArtist> iterable, boolean byName) {
if (iterable == null)
return new LinkedList<AdapterDTOArtist>();
else {
List<AdapterDTOArtist> collected = new LinkedList<AdapterDTOArtist>();
Iterator<AdapterDTOArtist> iterator = iterable.iterator();
if (iterator == null)
return collected;
while (iterator.hasNext()) {
AdapterDTOArtist item = iterator.next();
collected.add(item);
}
return collected;
}
}
}
My AdapterDTOArtist class :
public class AdapterDTOArtist {
private String mTag_Id;
private String mTag_Name;
public String getmTag_Name() {
return mTag_Name;
}
public void setmTag_Name(String mTag_Name) {
this.mTag_Name = mTag_Name;
}
public String getmTag_Id() {
return mTag_Id;
}
public void setmTag_Id(String mTag_Id) {
this.mTag_Id = mTag_Id;
}
}
My LazyAdapterArtist class:
public class LazyAdapterArtist extends BaseAdapter {
private Context mContext = null;
private ArrayList<AdapterDTOArtist> mAdapterDTOs = null;
public LazyAdapterArtist(Context context,
ArrayList<AdapterDTOArtist> mAdapterDTOs2) {
// TODO Auto-generated constructor stub
this.mContext = context;
this.mAdapterDTOs = mAdapterDTOs2;
}
public void setDataSet(ArrayList<AdapterDTOArtist> adapterDTOs) {
this.mAdapterDTOs = adapterDTOs;
notifyDataSetChanged();
}
#Override
public int getCount() {
// TODO Auto-generated method stub
return mAdapterDTOs.size();
}
#Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
#Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row = convertView;
ViewHolder mHolder = new ViewHolder();
if (row == null) {
// Cell is inflating for first time
row = LayoutInflater.from(mContext)
.inflate(com.whizpool.triplevmusic.R.layout.row_artists,
null, false);
mHolder.mNameTxt = (TextView) row
.findViewById(com.whizpool.triplevmusic.R.id.tv_row_artists);
row.setTag(mHolder);
} else {
// recycling of cells
mHolder = (ViewHolder) row.getTag();
}
mHolder.mNameTxt.setText(mAdapterDTOs.get(position).getmTag_Name());
return row;
}
static class ViewHolder {
TextView mNameTxt = null;
}
}
when parsed json data into listview my app look like this:
when enter word in edittext field then my app look like this:
I just want,when i entered the word for example i enter "D" then in a listview only those words were display which have starting word is "D".Thanks Alot and again sorry for my english.

The problem is that when you filter the data you add again to mAdapterDTOs list the results you need to clear the list before adding the results. To avoid losing your data you have to keep them in a separate list and when user times nothing show them.
Step 1: Use a field for keeping a backup of your data (just as mAdapterDTOs):
ArrayList<AdapterDTOArtist> mAdapterDTOs = null;
ArrayList<AdapterDTOArtist> mAdapterDTOsBackup= null;
Step 2: initialize that field:
mAdapterDTOs = new ArrayList<AdapterDTOArtist>();
mAdapterDTOsBackup = new ArrayList<AdapterDTOArtist>();
Step 3: Fill in all your data to the backup set just after parsing:
/**
* getting Albums JSON
* */
protected String doInBackground(String... args) {
// HERE all your code as it is!!!
// Just before return add a set keeping the backup of your data...
// initialize the set just as mAdapterDTOs
mAdapterDTOsBackup.addAll(mAdapterDTOs);
return null;
}
Step 4: When searching filter data from backup set and then add them on the mAdapterDTOs do not forget to clear it before.
et_artists_searchWord.addTextChangedListener(new TextWatcher() {
#Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
// TODO Auto-generated method stub
// ((Filterable) Artists.this.mAdapterDTOs).getFilter().filter(s);
List<AdapterDTOArtist> list = filter(s.toString(),mAdapterDTOsBackup, true);
mAdapterDTOs.clear(); // <--- clear the list before add
mAdapterDTOs.addAll(list); // <--- here is the double add if you do not clear before
mLazyAdatper.setDataSet(mAdapterDTOs);// update the adapter data (edit 2)
}
Edit: split answer in steps in order to be more clear the process also added at least one of your line to show where to add each code snippet.

How to refresh a listview in android using asynctask?

There are two Activities. The first Activity is having the list view to see what is being shared and the second activity has an edit text box (to input inorder to share) and a button. On clicking the button, it returns me the string which is the json response and I need to add this in the previous activity.
Now the problem is, when I refresh the first page fully hitting the server it gets the response but this is not what I want. It should not go back to the server. It should simply add in the list view adapter.
I have commented the code in the PostExecute(). I have tried the everyway but it is not reflecting. I am also posting my code for your reference.
public class ShareAsyncTask extends AsyncTask<String, Void, ArrayList<EventsStreamBean>> {
public ProgressDialog pd = new ProgressDialog(EventStreamActivity.this);
String success_share_val;
#Override
protected ArrayList<EventsStreamBean> doInBackground(
String... result) {
// TODO Auto-generated method stub
JSONObject jsonobj = new JSONObject(result[0].toString());
success_share_val = jsonobj.getString(Constants.SUCCESS);
//checks the success value
if(success_share_val.equalsIgnoreCase("1")) {
JSONArray events_stream_share_array = jsonobj.getJSONArray("streamArray");
if(events_stream_share_array.length() > 0) {
for(int i=0; i<events_stream_share_array.length(); i++) {
EventsStreamBean events_stream_bean = new EventsStreamBean();
JSONObject events_stream_object = events_stream_share_array.getJSONObject(i);
events_stream_bean.setStreamId(events_stream_object.getString(Constants.STREAM_ID));
events_stream_bean.setStreamType(events_stream_object.getString(Constants.STREAM_TYPE));
events_stream_bean.setUserId(events_stream_object.getString(Constants.USER_ID));
events_stream_bean.setUserName(events_stream_object.getString(Constants.USER_NAME));
events_stream_bean.setUserType(events_stream_object.getString(Constants.USER_TYPE));
events_stream_bean.setUserAvatar(events_stream_object.getString(Constants.USER_AVATAR));
arraylist_events_stream.add(events_stream_bean);
}
}else {
Log.i("Test", "No Events Streams Available");
}
}
}catch(Exception e) {}
return arraylist_events_stream;
}
#Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
this.pd.setMessage("Loading....");
pd.setCanceledOnTouchOutside(false);
pd.setCancelable(false);
this.pd.show();
}
#Override
protected void onPostExecute(final ArrayList<EventsStreamBean> result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
if(this.pd.isShowing()) {
this.pd.dismiss();
}
Toast.makeText(EventStreamActivity.this, "Post shared successfully", Toast.LENGTH_SHORT).show();
new EventsStreamAsyncTask().execute(temp_val);
/*runOnUiThread(new Runnable() {
public void run() {
//EventStream_Customadapter adapter = (EventStream_Customadapter) list_view.getAdapter();
//adapter.clearData();
adapter.updateData(result);
//adapter = new EventStream_Customadapter(EventStreamActivity.this, arraylist_events_stream);
//list_view.setAdapter(adapter);
//adapter.notifyDataSetChanged();
}
});*/
}
}
Thank you