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Passing spinner values to async task as an parameter

I am new to android. I need to pass values from the spinner to asynctask as an parameter and till now I am successful in showing the results in spinner successfully. Now i need to pass the selected value from the spinner to another activity on a button click (as an parameter to asynctask). Below is the code. Thanks in advance.
BackgroundFetchWorker.java:
public class BackgroundFetchWorker extends AsyncTask<String,Void,String> {
String json_string;
ProgressDialog progressDialog;
Context context;
BackgroundFetchWorker(Context ctx)
{
context = ctx;
}
#Override
protected String doInBackground(String... params) {
String type2 = params[0];
String student_fetch_url = "http://pseudoattendance.pe.hu/studentFetch.php";
if (type2.equals("fetchSubject")) {
try {
String semester = params[1];
String stream = params[2];
URL url = new URL(student_fetch_url);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoOutput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
String post_data = URLEncoder.encode("semester", "UTF-8") + "=" + URLEncoder.encode(semester, "UTF-8")
+ URLEncoder.encode("stream","UTF-8")+"="+URLEncoder.encode(stream,"UTF-8");
bufferedWriter.write(post_data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
String result = " ";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
return result;
} catch (IOException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onPreExecute() {
progressDialog = new ProgressDialog(context);
progressDialog.setTitle("Fetching Data....");
progressDialog.setMessage("This may take a while..");
progressDialog.show();
}
#Override
protected void onPostExecute(String result) {
progressDialog.dismiss();
String s = result.trim();
if(s.equals("{\"result\":[]}")){
Toast.makeText(context, "ERROR OCCURED", Toast.LENGTH_SHORT).show();
}
else {
json_string = result;
Intent i = new Intent(context, TakeAttendanceActivity.class);
i.putExtra("studentdata", json_string);
context.startActivity(i);
Toast.makeText(context, "Success", Toast.LENGTH_SHORT).show();
}
}
#Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
}
FacultyWelcomeActivity.java:
public class FacultyWelcomeActivity extends AppCompatActivity implements Spinner.OnItemSelectedListener{
String JSON_STRING;
JSONObject jsonObject;
JSONArray jsonArray;
ContactAdapter contactAdapter;
ListView listView;
//Declaring an Spinner
private Spinner spinner;
private Spinner spinner1;
//An ArrayList for Spinner Items
private ArrayList<String> students;
private ArrayList<String> stream;
//JSON Array
private JSONArray result;
private JSONArray result1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_faculty_welcome);
//Initializing the ArrayList
students = new ArrayList<String>();
stream = new ArrayList<String>();
//Initializing Spinner
spinner = (Spinner) findViewById(R.id.spinner);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String semesters= parent.getItemAtPosition(position).toString();
String stream= parent.getItemAtPosition(position).toString();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
spinner1 = (Spinner) findViewById(R.id.spinner1);
//Adding an Item Selected Listener to our Spinner
//As we have implemented the class Spinner.OnItemSelectedListener to this class iteself we are passing this to setOnItemSelectedListener
getData();
getData1();
listView = (ListView) findViewById(R.id.lectureList);
contactAdapter = new ContactAdapter(this, R.layout.rowlayout);
listView.setAdapter(contactAdapter);
JSON_STRING = getIntent().getExtras().getString("JSON Data");
try {
jsonObject = new JSONObject(JSON_STRING);
jsonArray = jsonObject.getJSONArray("result");
int count = 0;
String sub1, sub2, sub3, sub4;
while (count < jsonArray.length()) {
JSONObject JO = jsonArray.getJSONObject(count);
sub1 = JO.getString("fname");
sub2 = JO.getString("lname");
sub3 = JO.getString("id");
sub4 = JO.getString("email");
Contacts contacts = new Contacts(sub1, sub2, sub3, sub4);
contactAdapter.add(contacts);
count++;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
public void fetchSubject(View view) {
String type2 = "fetchSubject";
String spinnerdata = spinner.getSelectedItem().toString();
String spinner1data = spinner1.getSelectedItem().toString();
BackgroundFetchWorker background = new BackgroundFetchWorker(this);
background.execute(type2,spinnerdata,spinner1data);
}
private void getData1(){
StringRequest stringRequest = new StringRequest(Config2.DATA_URL,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
JSONObject j = null;
try {
//Parsing the fetched Json String to JSON Object
j = new JSONObject(response);
//Storing the Array of JSON String to our JSON Array
result1 = j.getJSONArray(Config2.JSON_ARRAY);
getStudents1(result1);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void getData(){
StringRequest stringRequest = new StringRequest(Config.DATA_URL,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
JSONObject j = null;
try {
//Parsing the fetched Json String to JSON Object
j = new JSONObject(response);
result = j.getJSONArray(Config.JSON_ARRAY);
getStudents(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void getStudents(JSONArray j){
for(int i=0;i<j.length();i++){
try {
//Getting json object
JSONObject json = j.getJSONObject(i);
students.add(json.getString(Config.TAG_SEMESTER));
} catch (JSONException e) {
e.printStackTrace();
}
}
spinner.setAdapter(new ArrayAdapter<String>(FacultyWelcomeActivity.this, android.R.layout.simple_spinner_dropdown_item, students));
}
private void getStudents1(JSONArray j){
//Traversing through all the items in the json array
for(int i=0;i<j.length();i++){
try {
//Getting json object
JSONObject json = j.getJSONObject(i);
//Adding the name of the student to array list
stream.add(json.getString(Config2.TAG_STREAM));
} catch (JSONException e) {
e.printStackTrace();
}
}
spinner1.setAdapter(new ArrayAdapter<String>(FacultyWelcomeActivity.this, android.R.layout.simple_spinner_dropdown_item, stream));
}
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
//check which spinner triggered the listener
}
#Override
public void onNothingSelected(AdapterView<?> parent) {}}

You are passing parameters to doInBackground() this way:
background.execute("your string");
Now the string "your string" will be the parameter within doInBackground() callback:
#Override
protected String doInBackground(String... params) {
String type2 = params[0]; // type2 == "your string"
...
}
See docs for more info.

listview not showing items android

I am have sql DB and I am trying to display queried values in a listView. I created a custom adapter for the listView. problem is
I am not able to see any data displayed on my listView.
code of main
public class _songs_playlist extends AppCompatActivity {
ArrayList<songsarray> listofsoongs = new ArrayList<songsarray>();
private static int SPLASH_TIME_OUT=2000;
AlertDialog alertDialog;
private boolean loggedIn = false;
String type;
String result;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity__songs_playlist);
new JSONParse().execute();
MyCustomAdapterSongs itemsAdapter = new MyCustomAdapterSongs(this, listofsoongs);
ListView listView = (ListView) findViewById(R.id.listView1);
listView.setAdapter(itemsAdapter);
itemsAdapter.notifyDataSetChanged();
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
alertDialog=new AlertDialog.Builder(_songs_playlist.this).create();
alertDialog.setTitle("Upadting Data");
pDialog = new ProgressDialog(_songs_playlist.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
HTTPHandler sh = new HTTPHandler();
String login_URL = "http://2f179dfb.ngrok.io/getsong.php";
try {
//Fetching the boolean value form sharedpreferences
URL url = new URL(login_URL);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
Log.e("RESULT", result);
JSONObject jsonObject = new JSONObject(result);
JSONArray result1 = jsonObject.getJSONArray("result");
for (int i = 0; i < result1.length(); i++) {
JSONObject c = result1.getJSONObject(i);
String id = c.getString("songID");
String names = c.getString("songName");
String ss = c.getString("singerName");
listofsoongs.add(new songsarray(ss,id,names));
}
return jsonObject;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
if(true)
{
}
else
{
}
}
}
}
code of custom array adapter
public class MyCustomAdapterSongs extends ArrayAdapter<songsarray> {
Context context;
ArrayList<songsarray> items;
public MyCustomAdapterSongs(Activity context, ArrayList<songsarray> songsarrays) {
super(context, 0, songsarrays);
this.context=context;
this.items=songsarrays;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View listItemView = convertView;
if (listItemView == null) {
listItemView = LayoutInflater.from(getContext()).inflate(
R.layout.itemlist, parent, false);
}
TextView nameTextView = (TextView) listItemView.findViewById(R.id.textView1);
nameTextView.setText(currentAndroidFlavor.getSingername());
Log.e("hhhh", nameTextView.getText().toString());
TextView numberTextView = (TextView) listItemView.findViewById(R.id.textView2);
numberTextView.setText(currentAndroidFlavor.getSongname());
Log.e("jjjj", numberTextView.getText().toString());
CheckBox ch=(CheckBox)listItemView.findViewById(R.id.checkBox1);
ch.setSelected(currentAndroidFlavor.isSelected());
return listItemView;
}
#Override
public int getCount() {
if(items == null)
return 0;
return items.size();
}
#Override
public songsarray getItem(int i) {
return items.get(i);
}
}

Call itemsAdapter.notifyDataSetChanged() within onPostExecute.
Your list is empty until the AsyncTask finishes there.
You'll have to make the adapter a member variable of the Activity class

As in your code I can see you are updating the list in doInBackground but you are not notifying the adapter for the changes.
In onPostExecute method you need to call itemsAdapter.notifyDataSetChanged() and make sure it you are not calling it inside doInBackground as in background thread you can't to UI related work.

Check the EDITS in this code snippet
`
public class _songs_playlist extends AppCompatActivity {
ArrayList<songsarray> listofsoongs = new ArrayList<songsarray>();
private static int SPLASH_TIME_OUT=2000;
AlertDialog alertDialog;
private boolean loggedIn = false;
String type;
String result;
//EDIT 1: Make these member variables
MyCustomAdapterSongs itemsAdapter;
ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity__songs_playlist);
//EDIT 2: get references your views before AsyncTask
listView = (ListView) findViewById(R.id.listView1);
new JSONParse().execute();
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
#Override
protected void onPreExecute() {
super.onPreExecute();
alertDialog=new AlertDialog.Builder(_songs_playlist.this).create();
alertDialog.setTitle("Upadting Data");
pDialog = new ProgressDialog(_songs_playlist.this);
pDialog.setMessage("Getting Data ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
}
#Override
protected JSONObject doInBackground(String... args) {
HTTPHandler sh = new HTTPHandler();
String login_URL = "http://2f179dfb.ngrok.io/getsong.php";
try {
//Fetching the boolean value form sharedpreferences
URL url = new URL(login_URL);
HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
result = "";
String line = "";
while ((line = bufferedReader.readLine()) != null) {
result += line;
}
bufferedReader.close();
inputStream.close();
httpURLConnection.disconnect();
Log.e("RESULT", result);
JSONObject jsonObject = new JSONObject(result);
JSONArray result1 = jsonObject.getJSONArray("result");
for (int i = 0; i < result1.length(); i++) {
JSONObject c = result1.getJSONObject(i);
String id = c.getString("songID");
String names = c.getString("songName");
String ss = c.getString("singerName");
listofsoongs.add(new songsarray(ss,id,names));
}
return jsonObject;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(JSONObject json) {
pDialog.dismiss();
//EDIT 3: set your adapter here as this method will be called on the UI Thread
itemsAdapter = new MyCustomAdapterSongs(this, listofsoongs);
listView.setAdapter(itemsAdapter);
}
}
}
}
`

code which one should I change to throw button and instantly displays my listview without having to click a button

code which one should I change to throw button and instantly displays my listview without having to click a button
public class MainActivity extends AppCompatActivity {
Button btnLoadFeed; <<<<<------------- Which should I remove associated with this code?
TextView textViewFeedUrl;
ListView listViewFeed;
List<FeedItem> listFeedItems;
ListAdapter adapterFeed;
String myFeed = "http://temfilm.blogspot.co.id/feeds/posts/default?alt=json";
//String myFeed = "http://arduino-er.blogspot.com/feeds/posts/default?alt=json";
//String myFeed = "http://helloraspberrypi.blogspot.com/feeds/posts/default?alt=json";
//String myFeed = "http://photo-er.blogspot.com/feeds/posts/default?alt=json";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnLoadFeed = (Button)findViewById(R.id.loadfeed);
textViewFeedUrl = (TextView)findViewById(R.id.feedurl);
setContentView(R.layout.layout_feed);
listViewFeed = (ListView)findViewById(R.id.listviewfeed);
listFeedItems = new ArrayList<>();
adapterFeed = new ArrayAdapter<FeedItem>(
this, android.R.layout.simple_list_item_1, listFeedItems);
listViewFeed.setAdapter(adapterFeed);
btnLoadFeed.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
textViewFeedUrl.setText(myFeed);
new JsonTask(listFeedItems, listViewFeed).execute(myFeed);
}
});
}
/*
JsonTask:
AsyncTask to download and parse JSON Feed of blogspot in background
*/
private class JsonTask extends AsyncTask<String, FeedItem, String> {
List<FeedItem> jsonTaskList;
ListView jsonTaskListView;
public JsonTask(List<FeedItem> targetList, ListView targetListView) {
super();
jsonTaskList = targetList;
jsonTaskListView = targetListView;
}
#Override
protected void onPreExecute() {
super.onPreExecute();
jsonTaskList.clear();
jsonTaskListView.invalidateViews();
}
#Override
protected String doInBackground(String... params) {
try {
final String queryResult = sendQuery(params[0]);
parseQueryResult(queryResult);
} catch (IOException e) {
e.printStackTrace();
final String eString = e.toString();
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(MainActivity.this,
eString,
Toast.LENGTH_LONG).show();
}
});
} catch (JSONException e) {
e.printStackTrace();
final String eString = e.toString();
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(MainActivity.this,
eString,
Toast.LENGTH_LONG).show();
}
});
}
return null;
}
#Override
protected void onProgressUpdate(FeedItem... values) {
FeedItem newItem = values[0];
jsonTaskList.add(newItem);
jsonTaskListView.invalidateViews();
}
private String sendQuery(String query) throws IOException {
String queryReturn = "";
URL queryURL = new URL(query);
HttpURLConnection httpURLConnection = (HttpURLConnection)queryURL.openConnection();
if(httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK){
InputStreamReader inputStreamReader =
new InputStreamReader(httpURLConnection.getInputStream());
BufferedReader bufferedReader = new BufferedReader(
inputStreamReader, 8192);
String line = null;
while((line = bufferedReader.readLine()) != null){
queryReturn += line;
}
bufferedReader.close();
}
return queryReturn;
}
private void parseQueryResult(String json) throws JSONException {
JSONObject jsonObject = new JSONObject(json);
final JSONObject jsonObject_feed = jsonObject.getJSONObject("feed");
final JSONArray jsonArray_entry = jsonObject_feed.getJSONArray("entry");
runOnUiThread(new Runnable() {
#Override
public void run() {
if(jsonArray_entry == null){
Toast.makeText(MainActivity.this,
"jsonArray_entry == null",
Toast.LENGTH_LONG).show();
}else{
Toast.makeText(MainActivity.this,
String.valueOf(jsonArray_entry.length()),
Toast.LENGTH_LONG).show();
for(int i=0; i<jsonArray_entry.length(); i++){
try {
JSONObject thisEntry = (JSONObject) jsonArray_entry.get(i);
JSONObject thisEntryTitle = thisEntry.getJSONObject("title");
String thisEntryTitleString = thisEntryTitle.getString("$t");
JSONArray jsonArray_EntryLink = thisEntry.getJSONArray("link");
//search for the link element with rel="alternate"
//I assume it's one and only one element with rel="alternate",
//and its href hold the link to the page
for(int j=0; j<jsonArray_EntryLink.length(); j++){
JSONObject thisLink = (JSONObject) jsonArray_EntryLink.get(j);
try{
String thisLinkRel = thisLink.getString("rel");
if(thisLinkRel.equals("alternate")){
try{
String thisLinkHref = thisLink.getString("href");
FeedItem thisElement = new FeedItem(
thisEntryTitleString.toString(),
thisLinkHref);
publishProgress(thisElement);
break;
}catch (JSONException e){
//no such mapping exists
}
}
}catch (JSONException e){
//no such mapping exists
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
});
}
}
}

I am trying to parse a data from the following link

"http://soccer.sportsopendata.net/v1/leagues/premier-league/seasons/16-17/standings" - Link Which Iam Trying to parse
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Button GetServerData = (Button) findViewById(R.id.GetServerData);
GetServerData.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// WebServer Request URL
String serverURL = "http://soccer.sportsopendata.net/v1/leagues/premier-league/seasons/16-17/standings";
// Use AsyncTask execute Method To Prevent ANR Problem
new LongOperation().execute(serverURL);
}
});
}
private class LongOperation extends AsyncTask<String, Void, Void> {
private final HttpClient Client = new DefaultHttpClient();
private String Content;
private String Error = null;
private ProgressDialog Dialog = new ProgressDialog(MainActivity.this);
String data = "";
TextView uiUpdate = (TextView) findViewById(R.id.textView2);
TextView jsonParsed = (TextView) findViewById(R.id.textView3);
int sizeData = 0;
EditText serverText = (EditText) findViewById(R.id.textView);
protected void onPreExecute() {
// NOTE: You can call UI Element here.
//Start Progress Dialog (Message)
Dialog.setMessage("Please wait..");
Dialog.show();
try {
// Set Request parameter
data += "&" + URLEncoder.encode("data", "UTF-8") + "=" + serverText.getText();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
#Override
protected Void doInBackground(String... urls) {
/************ Make Post Call To Web Server ***********/
BufferedReader reader = null;
// Send data
try {
// Defined URL where to send data
URL url = new URL(urls[0]);
// Send POST data request
URLConnection conn = url.openConnection();
conn.setDoOutput(true);
OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());
wr.write(data);
wr.flush();
// Get the server response
reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
StringBuilder sb = new StringBuilder();
String line = null;
// Read Server Response
while ((line = reader.readLine()) != null) {
// Append server response in string
sb.append(line + "");
}
// Append Server Response To Content String
Content = sb.toString();
} catch (Exception e) {
Error = e.getMessage();
} finally {
try {
reader.close();
} catch (Exception ex) {
}
}
return null;
}
protected void onPostExecute(Void unused) {
// NOTE: You can call UI Element here.
// Close progress dialog
Dialog.dismiss();
if (Error != null) {
uiUpdate.setText("Output : " + Error);
}else
{
//Show Response Json Onscreen(Activity)
uiUpdate.setText( Content );
/****************** Start Parse Response JSON Data *************/
String OutputData = "";
try {
JSONObject jsono = new JSONObject(Content);
JSONObject mainObject = jsono.getJSONObject("data");
JSONArray jsonArray = mainObject.getJSONArray("standing");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject object = jsonArray.getJSONObject(i);
// get details2 JSONObject
String position = object.optString("position").toString();
String team = object.optString("team").toString();
OutputData += "Position: " + position + " "
+ "Team Name : " + team + " ";
}
/****************** End Parse Response JSON Data *************/
//Show Parsed Output on screen (activity)
jsonParsed.setText( OutputData );
}catch (JSONException e) {
e.printStackTrace();
}
}
}
}
}
**I am Creating a premier league application which shows all the datas needed for a premier league fan. As Iam new to this I am getting confused over json parsing and getting data from apis. So Can anyone Explain to me how to change my code or Some links which would help me correct it.
Above given is my java code of Main Activity.**

Thank You Everyone for Helping out. But I found my answer from the search over the internet. Here I used VOLLEY to call the link.
JSON PARSER CLASS
public class ParseJSON {
public static String[] position1;
public static String[] team;
public static String[] points;
public static final String JSON_ARRAY = "data";
public static final String CHILD_ARRAY = "standings";
public static final String KEY_ID = "position";
public static final String KEY_NAME = "team";
private JSONObject users = null;
private JSONArray user2=null;
private JSONObject user3=null;
private String json;
public ParseJSON(String json){
this.json = json;
}
protected void parseJSON() {
JSONObject jsonObject = null;
try {
jsonObject = new JSONObject(json);
users = jsonObject.getJSONObject(JSON_ARRAY);
try {
user2=users.getJSONArray(CHILD_ARRAY);
position1 = new String[user2.length()];
team = new String[user2.length()];
points=new String[user2.length()];
for (int i = 0; i < user2.length(); i++) {
JSONObject jo = user2.getJSONObject(i);
try {
user3=jo.getJSONObject("overall");
points[i] = user3.getString("points");
System.out.println("Message me: "+points[i]);
}catch (Exception e)
{
e.printStackTrace();
}
position1[i] = jo.getString(KEY_ID);
team[i] = jo.getString(KEY_NAME);
System.out.println("Message me: "+position1[i]);
System.out.println("Message me: "+team[i]);
}
}catch (Exception e)
{
e.printStackTrace();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Main Activity Class
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
public static final String JSON_URL="http://soccer.sportsopendata.net/v1/leagues/premier-league/seasons/16-17/standings";
private Button buttonGet;
private ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonGet = (Button) findViewById(R.id.buttonGet);
buttonGet.setOnClickListener(this);
listView = (ListView) findViewById(R.id.listView);
}
#Override
public void onClick(View v) {
sendRequest();
}
private void sendRequest() {
final StringRequest stringRequest = new StringRequest(JSON_URL,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
showJSON(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(MainActivity.this, error.getMessage(), Toast.LENGTH_LONG).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
private void showJSON(String json){
ParseJSON pj = new ParseJSON(json);
pj.parseJSON();
CustomList cl = new CustomList(this, ParseJSON.position1,ParseJSON.team,ParseJSON.points);
listView.setAdapter(cl);
}
}
Custom Class for adding datas to list view
public class CustomList extends ArrayAdapter<String> {
private String[] position1;
private String[] team;
private String[] points;
private Activity context;
public CustomList(Activity context, String[] position1, String[] team, String[] points) {
super(context, R.layout.list_view_layout, position1);
this.context = context;
this.position1 = position1;
this.team = team;
this.points = points;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = context.getLayoutInflater();
View listViewItem = inflater.inflate(R.layout.list_view_layout, null, true);
TextView pos1 = (TextView) listViewItem.findViewById(R.id.position1);
TextView teamname = (TextView) listViewItem.findViewById(R.id.teamname);
TextView points1 = (TextView) listViewItem.findViewById(R.id.points);
pos1.setText("Position: "+position1[position]);
teamname.setText("Team: "+team[position]);
points1.setText("Points: "+points[position]);
return listViewItem;
}
}

Step 1 : Use Retroft + RxJava for Asynchronous API calls
Step 2 : Use Gson to Serialize and Deserialize.
Step 3 : Use json to POJO to have a Model Class
Simplify the code.

ListView Empty When Poputaing

I am trying to add items from database onto a listView, when I use System.out.println I see values but upon trying to populate them onto a custom listview returns no data in the listview.
When launching the app, I get a single row of listview item but of course it's empty.
public class MainActivity extends Activity implements AdapterView.OnItemClickListener {
String jsonResult;
String url = "http://www.mywebsite/query.php";
ListView list;
List<String> arrName;
List<String> arrNumber;
List<String> arrUsername;
List<String> arrStatus;
String name;
String number;
String username;
String status;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contacts);
arrName = Arrays.asList(name);
arrNumber = Arrays.asList(number);
arrUsername = Arrays.asList(username);
arrStatus = Arrays.asList(status);
list = (ListView) findViewById(R.id.listContacts);
ConatctsAdapter adapter = new ConatctsAdapter(this, arrName, arrNumber, arrUsername, arrStatus);
list.setAdapter(adapter);
list.setOnItemClickListener(this);
accessWebService();
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { //SINGLE CLICK
// TODO Auto-generated method stub
}
// Async Task to access the web
private class JsonReadTask extends AsyncTask<String, Void, String> {
#Override
protected String doInBackground(String... params) {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(
response.getEntity().getContent()).toString();
}
catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
}
catch (IOException e) {
// e.printStackTrace();
Toast.makeText(getApplicationContext(),
"Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
#Override
protected void onPostExecute(String result) {
ListDrwaer();
}
}// end async task
public void accessWebService() {
JsonReadTask task = new JsonReadTask();
// passes values for the urls string array
task.execute(new String[] { url });
}
// build hash set for list view
public void ListDrwaer() {
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("main");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
name = jsonChildNode.getString("Name");
number = jsonChildNode.getString("Number");
username = jsonChildNode.getString("Username");
status = jsonChildNode.getString("Status");
System.out.println("Name: "+name);
System.out.println("Number: "+number);
System.out.println("Username: "+username);
System.out.println("Status: "+status);
}
} catch (JSONException e) {
Log.i("Error Log: ", e.toString());
System.out.println("Error: "+e.toString());
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
ContactsAdapter adapter = new ContactsAdapter(this, arrName, arrNumber, arrUsername, arrStatus);
list.setAdapter(adapter);
list.setOnItemClickListener(this);
}
class ContactsAdapter extends ArrayAdapter<String>
{
Context context;
List<String> Name;
List<String> Number;
List<String> Username;
List<String> Status;
ContactsAdapter(Context c, List<String> Name, List<String> Number, List<String> Username, List<String> Status)
{
super(c, R.layout.activity_contacts_single, R.id.textName, Name);
this.context=c;
this.Name=Name;
this.Number=Number;
this.Username=Username;
this.Status=Status;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View row=convertView;
if(row==null)
{
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.activity_contacts_single, parent, false);
}
TextView txtName = (TextView) row.findViewById(R.id.textName);
TextView txtNumber = (TextView) row.findViewById(R.id.textNumber);
TextView txtUsername = (TextView) row.findViewById(R.id.textUsername);
TextView txtStatus = (TextView) row.findViewById(R.id.textStatus);
txtName.setText(Name.get(position));
txtNumber.setText(Number.get(position));
txtUsername.setText(Username.get(position));
txtStatus.setText(Status.get(position));
return row;
}
}
}

It's because you haven't add those items into your lists, Change this part of your code:
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("main");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
name = jsonChildNode.getString("Name");
number = jsonChildNode.getString("Number");
username = jsonChildNode.getString("Username");
status = jsonChildNode.getString("Status");
//add this part to your code
arrName.add(name);
arrNumber.add(number);
arrUsername.add(username);
arrStatus.add(status);
System.out.println("Name: "+name);
System.out.println("Number: "+number);
System.out.println("Username: "+username);
System.out.println("Status: "+status);
}
} catch (JSONException e) {
Log.i("Error Log: ", e.toString());
System.out.println("Error: "+e.toString());
Toast.makeText(getApplicationContext(), "Error" + e.toString(),
Toast.LENGTH_SHORT).show();
}
ContactsAdapter adapter = new ContactsAdapter(this, arrName, arrNumber, arrUsername, arrStatus);
list.setAdapter(adapter);
list.setOnItemClickListener(this);
}
for your second problem I think you can change your code this way:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contacts);
//arrName = Arrays.asList(name);
//arrNumber = Arrays.asList(number);
//arrUsername = Arrays.asList(username);
//arrStatus = Arrays.asList(status);
arrName = new ArrayList<String>();
arrNumber =new ArrayList<String>();
arrUsername =new ArrayList<String>();
arrStatus =new ArrayList<String>();
list = (ListView) findViewById(R.id.listContacts);
ConatctsAdapter adapter = new ConatctsAdapter(this, arrName, arrNumber, arrUsername, arrStatus);
list.setAdapter(adapter);
list.setOnItemClickListener(this);
accessWebService();
}