Develop Reference

Why do I get an empty response when my android app calls my API on my server?

I have android application that called information and show it as a list.
I have a spinner when you choose the date from the spinner you get the information related to that date.
In the app first load it calls automatically today information.
this is the code I use in my main activity to create my spinner and fill it with elements and handle the clicks on each item:
// Spinner element
spinner = (Spinner) v.findViewById(R.id.spinner);
// Spinner click listener
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parent, View view,
int position, long id) {
// On selecting a spinner item
//String item = parent.getItemAtPosition(position).toString();
switch(position){
case 3:
if (JsonUtils.isNetworkAvailable(getActivity())) {
list.clear();
new MyTask().execute(Config.SERVER_URL + "/banko_api.php?d_o=-1");
} else {
Toast.makeText(getActivity(), getResources().getString(R.string.failed_connect_network), Toast.LENGTH_SHORT).show();
}
break;
case 4:
if (JsonUtils.isNetworkAvailable(getActivity())) {
list.clear();
new MyTask().execute(Config.SERVER_URL + "/banko_api.php?d_o=0");
} else {
Toast.makeText(getActivity(), getResources().getString(R.string.failed_connect_network), Toast.LENGTH_SHORT).show();
}
break;
case 5:
if (JsonUtils.isNetworkAvailable(getActivity())) {
list.clear();
new MyTask().execute(Config.SERVER_URL + "/banko_api.php?d_o=1");
} else {
Toast.makeText(getActivity(), getResources().getString(R.string.failed_connect_network), Toast.LENGTH_SHORT).show();
}
break;
default:
if (JsonUtils.isNetworkAvailable(getActivity())) {
list.clear();
new MyTask().execute(Config.SERVER_URL + "/banko_api.php?d_o=0");
} else {
Toast.makeText(getActivity(), getResources().getString(R.string.failed_connect_network), Toast.LENGTH_SHORT).show();
}
break;
}
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
Calendar calendar = Calendar.getInstance();
Date today = calendar.getTime();
calendar.add(Calendar.DAY_OF_YEAR, -1);
Date yesterday = calendar.getTime();
calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_YEAR, 1);
Date tomorrow = calendar.getTime();
DateFormat dateFormat = new SimpleDateFormat("dd/MM EEE");
String todayAsString = dateFormat.format(today);
String tomorrowAsString = dateFormat.format(tomorrow);
String yesterdayAsString = dateFormat.format(yesterday);
// Spinner Drop down elements
List<String> categories = new ArrayList<String>();
categories.add(yesterdayAsString);
categories.add(todayAsString);
categories.add(tomorrowAsString);
// Creating adapter for spinner
ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(getContext(), R.layout.spinner_item, categories);
dataAdapter.setDropDownViewResource(R.layout.spinner_dropdown_item);
// attaching data adapter to spinner
spinner.setAdapter(dataAdapter);
spinner.setSelection(4);
The problem : first load of the app is calling the data of today (which is the default choice in my spinner) without any problem.
if i choose another element in the spinner it also calls the related data without problem.
now if I want to select back today element in the spinner no data will be brought from the server even when the app at the start up it calls data from the same link and get it.
I get this message in my log :
W/System.err: org.json.JSONException: Value [] of type org.json.JSONArray cannot be converted to JSONObject
The onPostExcute of my Asynktask contains this code:
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
if (null != progressDialog && progressDialog.isShowing()) {
progressDialog.dismiss();
}
if (null == result || result.length() == 0) {
Toast.makeText(getActivity(), getResources().getString(R.string.failed_connect_network), Toast.LENGTH_SHORT).show();
} else {
try {
Log.d("resultTT",result);
JSONObject mainJson = new JSONObject(result);
JSONArray jsonArray = mainJson.getJSONArray(JsonConfig.CATEGORY_ARRAY_NAME);
JSONObject objJson = null;
for (int i = 0; i < jsonArray.length(); i++) {
objJson = jsonArray.getJSONObject(i);
ItemMatch objItem = new ItemMatch();
objItem.setMatchId(objJson.getString(JsonConfig.Match_ID));
objItem.setMatchTournamentName(objJson.getString(JsonConfig.Match_LEAGUE_NAME));
objItem.setMatchTime(objJson.getString(JsonConfig.Match_TIME));
objItem.setMatchStatus(objJson.getString(JsonConfig.Match_STATUS));
objItem.setMatchLocalTeamName(objJson.getString(JsonConfig.Match_LOCALTEAM_NAME));
objItem.setMatchVisitorTeamName(objJson.getString(JsonConfig.Match_VISITORTEAM_NAME));
objItem.setMatchLocalTeamGoals(objJson.getString(JsonConfig.Match_LOCALTEAM_GOALS));
objItem.setMatchVisitorTeamGoals(objJson.getString(JsonConfig.Match_VISITORTEAM_GOALS));
objItem.setMatchBestOddPercent(objJson.getString(JsonConfig.Match_BEST_ODD_PERCENT));
objItem.setMatchBestOddResult(objJson.getString(JsonConfig.Match_BEST_ODD_RESULT));
list.add(objItem);
}
} catch (JSONException e) {
e.printStackTrace();
}
for (int j = 0; j < list.size(); j++) {
object = list.get(j);
array_match_id.add(String.valueOf(object.getMatchId()));
str_match_id = array_match_id.toArray(str_match_id);
array_league_name.add(String.valueOf(object.getMatchTournamentName()));
str_league_name = array_league_name.toArray(str_league_name);
array_match_time.add(String.valueOf(object.getMatchTime()));
str_match_time = array_match_time.toArray(str_match_time);
array_match_status.add(String.valueOf(object.getMatchStatus()));
str_match_status = array_match_status.toArray(str_match_status);
array_match_localteam_name.add(object.getMatchLocalTeamName());
str_match_localteam_name = array_match_localteam_name.toArray(str_match_localteam_name);
array_match_visitorteam_name.add(object.getMatchVisitorTeamName());
str_match_visitorteam_name = array_match_visitorteam_name.toArray(str_match_visitorteam_name);
array_match_localteam_goals.add(object.getMatchLocalTeamGoals());
str_match_localteam_goals = array_match_localteam_goals.toArray(str_match_localteam_goals);
array_match_visitorteam_goals.add(object.getMatchVisitorTeamGoals());
str_match_visitorteam_goals = array_match_visitorteam_goals.toArray(str_match_visitorteam_goals);
array_match_best_odd_percent.add(object.getMatchBestOddPercent());
str_match_best_odd_percent = array_match_best_odd_percent.toArray(str_match_best_odd_percent);
array_match_best_odd_result.add(object.getMatchBestOddResult());
str_match_best_odd_result = array_match_best_odd_result.toArray(str_match_best_odd_result);
}
setAdapterToListView();
}
In the try section of this code u can see I make a log of the result to see what is coming from the server i just get this : D/resultTT: []
and as you see the try is inside the else section so in the if statement of this section i check if the result is null or empty ; but the code passes it and enter the else statement but still showing that the returned result array is empty.
I want some help to find the reason behind this empty returned array even it loads fine at the start up. why can not it get the information after I choose any element in the spinner and then come back to the default (today) element?
UPDATE : this is my php side-server api code
<?php
include_once ('includes/variables.php');
DEFINE ('DB_HOST', $host);
DEFINE ('DB_USER', $user);
DEFINE ('DB_PASSWORD', $pass);
DEFINE ('DB_NAME', $database);
$mysqli = #mysql_connect (DB_HOST, DB_USER, DB_PASSWORD) OR die ('Could not connect to MySQL');
#mysql_select_db (DB_NAME) OR die ('Could not select the database');
?>
<?php
mysql_query("SET NAMES 'utf8'");
$date_offset = mysql_real_escape_string($_GET[d_o]);
//$date_offset = 0;
if(empty($date_offset) || $date_offset == "0")
{
$date_offset_value = "0";
$query="SELECT a.*, m.match_id, m.match_time, m.en_tournament_name FROM app_banko a inner join matches_of_comments m on m.match_id = a.match_id where a.date_offset = $date_offset_value limit 20";
$resouter = mysql_query($query);
}
else
{
$date_offset_value = $date_offset;
$query="SELECT a.*, m.match_id, m.match_time, m.en_tournament_name FROM app_banko a inner join matches_of_comments m on m.match_id = a.match_id where a.date_offset = $date_offset_value limit 20";
$resouter = mysql_query($query);
}
$set = array();
$total_records = mysql_num_rows($resouter);
if($total_records >= 1){
while ($link = mysql_fetch_array($resouter, MYSQL_ASSOC)){
$set['NewsApp'][] = $link;
}
}
echo $val= str_replace('\\/', '/', json_encode($set));
?>

If you get an array in return when expecting an object, there might be something wrong with the request to the API. One way is to figure it out it set up Wireshark on the development machine to sniff and filter the traffic. Then you can see if your request is faulty.

It is possible that the value of the response argument from the onPostExecute method contains stringified JSONArray, not JSONObject.
You can always test this with:
try:
JSONArray jsonArray = new JSONArray(result);
catch(JSONException e) {
// String `result` is not an array. Parse it as a regular JSONObject.
}
Testing wheter string is an empty json array (depends on it's formatting, especially when it may contain some white characters) checking it's length might be a pretty bad idea.
It all depends how are determined an API endpoints that you are calling.
One more tip at the end. If you are planning to consume REST API I strongly recommend using:
Retrofit - which allows you to easily define interfaces to access your API,
GSON - to automatically convert responses for Java models.

Your result string is an empty array but not an empty string. The empty array is represented as the following string:
String result = "[]";
In that case result.length() is equal to 2.
When parsing JSON you need to know if the parsed object is of type Object or of type Array. The former one is wrapped with braces {}, the later one with square brackets [].
So the following line:
JSONObject mainJson = new JSONObject(result);
Should probably be:
JSONArray mainJson = new JSONArray(result);
But I cannot emphasize enough that you need to know what your API returns if you want to be able to parse it correctly.
EDIT:
Well, json_encode will have a hard time to guess whether it should create a JSON Array or a JSON Object out of the empty array that you created with $set = array();.
Adding objects to the array like you do in your loop makes it obvious for json_encode that it should create a JSON Object.
I don't know if you can force json_encode's behavior, but worst case you could check yourself if the array is empty and return "" or null if the array is empty.
$set = array();
$total_records = mysql_num_rows($resouter);
if ($total_records >= 1) {
while ($link = mysql_fetch_array($resouter, MYSQL_ASSOC)) {
$set['NewsApp'][] = $link;
}
echo $val= str_replace('\\/', '/', json_encode($set));
} else {
echo $val="";
}

please put a check result.isEmpty() in your try block condition may this could solve your problem.

you can not directly get response in string . it can use JSONObject and JSONArray.

Calling Async task in a loop?

I want to call an Async task in a loop and execute it a few times in parallel.
I have a List of items which I split out into smaller lists with 10 items in each list.
Then for every small List I execute the Async task using THREAD_POOL_EXECUTOR.
Problem is, its not working. I'm thinking its because I use the same list each time when it is passed to the AsyncTask - and I think it may be passed as reference.
Do I need to somehow create new Lists dynamically?
//split the ListItems into 10s
if (actualThumbs.size() > 10){
List<List<ListItem>> parts = chopped(actualThumbs, 10); // this splits it into parts of 10
List< ListItem > listToSend = new ArrayList<ListItem>(); //this is the list to pass
for(int i = 0; i < parts.size(); i++){ //for every part
for(int x = 0; x < parts.get(i).size(); x++){ //for everything in that part
//add to its own List
listToSend.add(parts.get(i).get(x));
}
//this is the async task
loadActualThumbs thumbs = new loadActualThumbs();
//execute multiple threads
thumbs.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR,listToSend );
listToSend.clear(); //clearing the list ready for a new one - PROBLEM?
}
}
else
{
//else just execute AsyncTask normally, this works OK
loadActualThumbs thumbs = new loadActualThumbs();
thumbs.execute(actualThumbs);
}
EDIT:
I tried changing my code, to instead add every List that I want to send to the Async task to another List, and then loop through that List of Lists and send each one:
if (actualThumbs.size() > 10){
List<List<ListItem>> parts = chopped(actualThumbs, 10);
List< ListItem > listToSend = new ArrayList<ListItem>();
List<List<ListItem>> sendMe = new ArrayList<List<ListItem>>();
for(int i = 0; i < parts.size(); i++){ //for every part
for(int x = 0; x < parts.get(i).size(); x++){ //for everything in that part
//add to its own ListItem?
listToSend.add(parts.get(i).get(x));
}
sendMe.add(listToSend);// add the List to this List
listToSend.clear();
}
for(int e = 0; e<sendMe.size();e++){ //loop through the list of lists
loadActualThumbs thumbs = new loadActualThumbs();
//execute multiple threads?
thumbs.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR,sendMe.get(e) ); // execute async with correct List
}
}
else
{
if (actualThumbs.size() > 0){
//load actual thumbnails
loadActualThumbs thumbs = new loadActualThumbs();
thumbs.execute(actualThumbs);
}
}

Your code should look like this now :
List<List<ListItem>> parts = chopped(actualThumbs, 10);
for(List<ListItem> list : parts) {
new loadActualThumbs().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, list);
}
I am actually not sure what size the threadpool is or if it's a cached thread pool, but you can create your own threadpool with Executors.newCachedThreadPool() and Executors.newFixedThreadPool(int count)... but I'd just go with the AsyncTask.THREAD_POOL_EXECUTOR....should work :)

If you need to execute your asynctask for particular interval of time then you may make use of Timer for same ..
Like this ..
Timer timer = new Timer();
TimerTask doAsynchronousTask = new TimerTask() {
#Override
public void run() {
try {
System.out
.println("=================== I am in pooling state ===============");
GetBookingStatusAsyncTask performBackgroundTask = new GetBookingStatusAsyncTask();
performBackgroundTask.execute();
} catch (Exception e) {
e.printStackTrace();
}
}
};
Now when you need to kill this timer ..
timer.cancel();
timer = null;
Also make use of boolean check so as to avaoid infinite loop .. i.e if true then execute AsyncTask .. and if false then stop AsyncTask .. just like ..
public void callAsynchronousTask(boolean b) {
// timer.cancel();
if (b) {
System.out.println("============= Check for timer check " + tcheck);
// execute in every 10000 ms
tcheck++;
} else {
System.out
.println("============= Check for timer check + cancelling timer task "
+ tcheck);
timer.cancel();
timer = null;
System.out.println("=============timer is ===" + timer);
// finish();
return;
}
}
When you need to close this task then simply of true / false condition pass like ..you need to pass this in your AsyncTask.
callAsynchronousTask(true); / callAsynchronousTask(false);
Hope it helps!..

AsyncTask do not work in for loop

My AsyncTask class do not work inside for loop. Below is my code please review it.
for (int i = 0; i < size; i++) {
String id = careplan_disease_Parser.DiseaseID.get(i);
String method = "GetCarePlan_Comment?CurrentValue=0&OptionId=" + id + "&DiseaseID=" + id + "&OrgId=" + orgId + "";
String link = "GetCarePlan_Comment_dislink";
task = new AsyncTask123();
task.execute(link, method);
method=null;
link=null;
task=null;
}
Task executes only once. so i can't get value from web service second time in a loop.
Please help me how to make it work.
Thanks

You can write a start-method, that gets called in the onPostExecute-part of you AsyncTask. It should look like this:
private void start(int number)
{
if(number == size)
{
//exit
}
else
{
new AsyncTask123().execute(link, method);
}
}
private class AsyncTask123 extends AsyncTask<> {
protected void onPostExecute() {
start(i++);
}
}
This should work, you just have to fit it for your needs.

if you want AsyncTask in for loop then you should call your class like:
new AsyncTask123().execute(link, method);
Not like :
task = new AsyncTask123();
task.execute(link, method);

Android AsyncTask and NetworkOnMainThreadException

I am working on an Android app that uses Jsoup. Early on in development, I "worked around" having to implement any kind of threading because I just wanted to get the bulk of the code completed before tackling threading. I am now attempting to use AsyncTask, but I am still getting the NetworkOnMainThreadException error. I have read plenty of tutorials and SO posts on AsyncTask, but still can seem to identify the problem. When I add the StrictMode... code, the app works as desired except for the UI lockup when loading the data using Jsoup. If anyone could show me what I am doing wrong pertaining to AsyncTask, I would appreciate it. (P.S. I know there is plenty of code redundancy to be cleaned up, but I want to get AsyncTask working first)
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/***This is the work around used***/
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
/******/
up = new TreeMap<Double, String[]>();
c1 = "example.com/1";
//instansiate textviews (6)
doc1 = doc;
c2 = "example.com/2";
//instansiate textviews (6)
doc2 = doc;
c3 = "example.com/3";
//instansiate textviews (6)
doc3 = doc;
// instansiate textviews(16)
new Download().execute(c1,c2,c3);
}
private class Download extends AsyncTask<String, Integer, String[][]> {
#Override
protected String[][] doInBackground(String... urls){
out = new String[7][3];
try {
doc = Jsoup.connect(urls[0]).data().get();
//days, times, and cs arrays created and filled
String[] out1arr = {days[0], times[0], cs[0]};
//...all 7
String[] out7arr = {days[6], times[6], cs[6]};
String[][] outarrs = {out1arr,out2arr,out3arr,out4arr,out5arr,out6arr,out7arr};
for (int i= 0; i < out.length; i++){
out[i] = outarrs[i];
}
} catch (IOException e1) {
e1.printStackTrace();
}
return (out);
}
#Override
protected void onProgressUpdate(Integer... progress){
}
#Override
protected void onPostExecute(String[][] result){
Do(/*textviews(6)*/, c1, a, outa, "example1"); //a is previously instantiated double array, outa is preiously instantiated string array
Do(/*textviews(6)*/, c2, b, outb, "example2");
Do(/*textviews(6)*/, c3, c, outc, "example3");
upc00.setText(getUpc()[0][0]);
//setText for all 16
upc32.setText(getUpc()[3][2]);
}
private void Do(TextView t, TextView u, TextView v, TextView w, TextView x, TextView y,String webpage, double[] darr, String[] sarr, String show){
t.setText(doInBackground(webpage)[0][0]);
//...all 6
y.setText(doInBackground(webpage)[1][2]);
for (int i =0; i < darr.length; i++){
darr[i] = tis[i];
up.put(darr[i], out[i]);
}
}
}
private ArrayList<String[]> getMap(){
//...
return s;
}
private String[][] getUpc(){
//...
return upc;
}

The framework calls doInBackground you should not call it yourself. Your code makes a call from onPostExecute which is called by the framework on the UI thread. So effectively your calls run on the UI thread.
Move your fetching logic all into the doInBackgound method. The onPostExecute method should be used to deliver the results to the caller.

Pulling data from a remote mySQL database, using AsyncTask; only displaying very last table row

As the title says really. I have two columns. I want to put them into textviews so I did it. However only the bottom two results, one from each column gets shown. Very odd. Here is my code: http://pastebin.com/qNgfHfT3
The parsing/onPostExecute is towards the bottom where the issue is.
One thing to note: The logs labeled "work" & "dontwork" show all my results, however the logs in the onPostExecute (Google & Google1) only show the last result so I presume the error is in the transfer from parsing to displaying.
Would really appreciate any help here. Thanks.

If you are receiving a JSON response I'd suggest you to parse it by using Gson. It's strongly recommendable as long as you can parse the whole thing in a pair of lines.
Note that creating a proper object it is as easy as doing the following:
YourObject object = gson.fromJson(responseReader, YourObject.class);
or even if you are retrieving a list of items:
Type listType = new TypeToken<List<YourObject>>() {}.getType();
List<YourObject> objects = gson.fromJson(responseReader, listType);
Here's an example that fits exactly your needs
After the process is done you'll have your object (or list of objects) available in an accesible variable.
EDIT:
First your Asynctask should have the following params:
public class HttpTask extends AsyncTask<Void, Void, ArrayList<Driver>> {
and your doInBackground method will need to pass that array to your onPostExecute:
#Override
protected ArrayList<Driver> doInBackground(Void... params) {
For the rest, I take it when the JSon parsing starts.
//PARSING JSON DATA
try {
JSONObject json_data;
Driver d;
jArray = new JSONArray(result);
int l = jArray.length();
if(l>0){
ArrayList<Driver> drivers = newArrayListList<Driver>();
for (int i = 0; i < l; i++) {
json_data = jArray.getJSONObject(i);
d = new Driver(json_data.optString("Driver_full_name"), json_data.optString("Drives_for"));
drivers.add(d);
Log.i("work", returnString);
Log.i("dontwork", somethingelse);
}
} catch (JSONException e1) {
Log.d("DB", "Error somewhere");
CurrentSeasonDrivers_DriverName.this.runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(CurrentSeasonDrivers_DriversName, "Could not parse data so shut up", Toast.LENGTH_LONG).show();
}
});
}
return drivers;
}
protected void onPostExecute(ArrayList<Drivers>... drivers) {
Log.i("Google", returnString);
Log.i("Google1", somethingelse);
String firstDriverName = drivers.get(0).name;
String firstDriverDrivesFor = drivers.get(0).drivesfor;
String secondDriverName = drivers.get(1).name;
TextView drivername = (TextView) findViewById(R.id.DriverName);
drivername.setText(firstDriverName);
TextView drivesfor = (TextView) findViewById(R.id.DrivesFor);
drivesfor.setText(firstDriverDrivesFor);
}
With this and an object for your driver will complete the circle.
public class Driver{
public String name;
public String drivesfor;
public Driver(String _name, String _drivesfor){
name = _name;
drivesfor = _drivesfor;
}
}
I guess you can take over from here.
Let me know about your progress.