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.

Get property value and check for existence and null

I am writing a custom deserializer for a json object and I have a property in the json that may not exist and if it exists its value may be null.
JsonObject obj = ....;
String value = "";
// first check if exists
if (obj.has("someProperty")) {
// get the proprty
JsonElement element = obj.get("someProperty");
// better check if its null
if (!element.isJsonNull()) {
// ah yes finally have the value
value = element.getAsString();
}
}
Yup works great, but extremely verbose. Combing the GSON api to find a better way with no luck. Is there an easier way?

Maybe this one would be a little bit better:
JsonElement element = obj.get("someProperty");
if (element != null && !element.isJsonNull()) {
value = element.getAsString();
}

You should use org.json.JSONObject; and do the following.
JSONObject obj1 = new JSONObject();
String value = "";
// will set value to your element if it exists otherwise will return empty string
value = obj1.optString("someProperty");

string index out of bound exception while carrying search operation

when I am carrying out a search operation after fetching the contacts,it shows this exception when I type the letters very fast in the search bar and the application crashes.Could you please help me out to resolve this issue.I am including the portion of the code also along
#Override
public boolean onQueryTextChange(String newtext) {
String searchString = newtext;
int textLength = searchString.length();
ArrayList<Masterlistmodel> type_name_filter = new ArrayList<Masterlistmodel>();
/* String text = edtField.getText().toString(); */
for (int i = 0; i <masterarr.size(); i++) {
String Name = masterarr.get(i).getName();
if (searchString.equalsIgnoreCase(Name.substring(0,
textLength))) {
type_name_filter.add(masterarr.get(i));
}
}
type_name_copy = type_name_filter;
listUpdate(type_name_copy);
return true;
}
#Override
public boolean onQueryTextSubmit(String arg0) {
// TODO Auto-generated method stub
return false;
}

First thing I'd point out is that we don't know what kind of object is masterarr, So I'll guess is like an ArrayList.
I'd try not to use the .size() but the .length() method, size is related to capacity and length is related to the amount of items actually in the array.
Also, as #rsinha said, I think a possible mistake is when you try to execute the equalsIgnoreCase method and the Name variable in that iteration has a lenght shorter than the lenght of the String typed by the user, so I would try:
for (int i = 0; i <masterarr.size(); i++) {
String Name = masterarr.get(i).getName();
if (searchString.equalsIgnoreCase(Name.substring(0,
Math.min(textLength,Name.length())))) {
type_name_filter.add(masterarr.get(i));
}
}
Try first using .length() and if does not work, try the changes in the for loop. I see no more in your code I could help with.

You get IndexOutOfBoundsException when you want to access an array index which is out of range. For example:
String[] myArray = new String[10];
myArray[10] = "test"; // 10 is out of limits(0-9)
Would produce such an exception.
with this:
ArrayList<String> result= new ArrayList<String>();
Then you can add elements to this list with the following:
// result[i] = trax.substring(s1+4,s2);
result.add(trax.substring(s1+4,s2));
It will work for you and it will remove this exception.

'textLength' is length of the search string entered by user. An entry of this length may not be in your master list 'masterarr'. You may try:
String Name = masterarr.get(i).getName();
if (Name.startsWith(searchString)) {
type_name_filter.add(masterarr.get(i));
}

Add the first statement in the method "onQueryTextChange"
if(newtext==null) return true;
Then try

How to convert string into boolean array?

I convert everything in my Android app into string and add it to a Sqlite database. I use the code below to convert boolean arrays into string, but I dont know how to convert it back from string into boolean array. There spaces between each true and false in the string. How can I break string at each space into a boolean array?
String work= "";
for (int i = 0;i<go.length; i++) {
work= work+go[i];
// Do not append comma at the end of last element
if(i<go.length - 1){
work = work+" ";
}
}

Split the string on your separator character (" ")
Create an array of booleans with the same length of the splitted array of strings
Parse one by one them using Boolean.parseBoolean method
Example:
public static void main(String[] args) {
String str = "true false true false false";
String[] parts = str.split(" ");
boolean[] array = new boolean[parts.length];
for (int i = 0; i < parts.length; i++)
array[i] = Boolean.parseBoolean(parts[i]);
System.out.println(Arrays.toString(array));
}
Outputs:
[true, false, true, false, false]

Please use boolean b = Boolean.parseBoolean(string);

Android: Can't parse null values from SOAP response (kSoap2)

When parsing the SoapObject data into a String[], the empty fields in the response from the webservice do not get added to it and I can't identify the empty propeties by checking for null or "".
So my problem is basically: The SoapObject contains the right amount of properties, but the parsed result (String[]) does not contain the ones that are empty, nor can I check for empty properties and add "" to the String[].
This causes problems for me when saving to the SQLite DB since every e.g. "User" contains a different amount of fields.
public static String[] getStringArrayResponse(SoapObject node, Vector<String> strings) {
boolean isFirstCall = false;
if (strings == null) {
isFirstCall = true;
strings = new Vector<String>();
}
int count = node.getPropertyCount();
for (int i = 0; i < count; i++) {
Object obj1 = node.getProperty(i);
if (obj1 instanceof SoapObject) {
if (((SoapObject)obj1).getPropertyCount() > 0) {
// Returns the correct amount of properties
Log.d("PARSER", "propertycount = " +((SoapObject)obj1).getPropertyCount());
getStringArrayResponse((SoapObject)obj1, strings);
}
} else if (obj1 instanceof SoapPrimitive) {
strings.add(((SoapPrimitive)obj1).toString());
}
}
if (isFirstCall) {
return (String[])strings.toArray(new String[strings.size()]);
}
return null;
}
This is really giving me a headache and I'm grateful for any help I can get :)

I needed to check for "AnyType{}" :)
if (obj1.toString().equals("anyType{}")){
strings.add("");
}
Just added this block of code below the else if.