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.

check for empty fields android

code gets two user inputs from user and compares inputs to a database and prints out d corresponding data from the database.how do i add code to check for empty fields?
protected void onPostExecute(Void v) {
try {
boolean available=false;
JSONArray Jarray = new JSONArray(result);
for(int i=0;i<Jarray.length();i++) {
JSONObject Jasonobject = null;
//text_1 = (TextView)findViewById(R.id.txt1);
Jasonobject = Jarray.getJSONObject(i);
//get an output on the screen
//String id = Jasonobject.getString("id");
String name = Jasonobject.getString("name");
String name1 = Jasonobject.getString("name1");
String db_detail = "";
if (et.getText().toString().equalsIgnoreCase(name) && et1.getText().toString().equalsIgnoreCase(name1)||et.getText().toString().equalsIgnoreCase(name1) && et1.getText().toString().equalsIgnoreCase(name)) {
db_detail = Jasonobject.getString("detail");
text.setText(db_detail);
available = true;
break;
}
}
if(!available)
Toast.makeText(MainActivity.this, "Not available", Toast.LENGTH_LONG).show();
this.progressDialog.dismiss();
}

Use TextUtils.isEmpty(charactersequence)
if(!TextUtils.isEmpty(et.getText().toString().equalsIgnoreCase(name)))
{
}
Docs :
public static boolean isEmpty (CharSequence str)
Added in API level 1
Returns true if the string is null or 0-length.
Parameters
str the string to be examined
Returns
true if str is null or zero length
Also better to use optString
Jasonobject.optString("name");

You can use String.isEmpty() method which checks whether the length of the String is 0.
You can also try on String.matches().
Using equalsIgnoreCase("") performs an actual string comparison. This method returns true if the argument is not null and the Strings are equal, ignoring case; false otherwise.
So you may check using isEmpty() or matches("") method to check empty values and then do the comparison.

suppose your string you received is as below,
String nameString = jsonObj.getString("name");
you can check if its empty by using following check.
if(nameString.equals(""))

How to remove duplicates from ArrayList of type Object? [duplicate]

This question already has answers here:
How to remove duplicates from a list?
(15 answers)
Closed 8 years ago.
I want to remove duplicates from ArrayList of type Alerts where Alerts is a class.
Class Alerts -
public class Alerts implements Parcelable {
String date = null;
String alertType = null;
String discription = null;
public Alerts() {
}
public Alerts(String date, String alertType, String discription) {
super();
this.date = date;
this.alertType = alertType;
this.discription = discription;
}
}
Here is how I added the elements -
ArrayList<Alerts> alert = new ArrayList<Alerts>();
Alerts obAlerts = new Alerts();
obAlerts = new Alerts();
obAlerts.date = Date1.toString();
obAlerts.alertType = "Alert Type 1";
obAlerts.discription = "Some Text";
alert.add(obAlerts);
obAlerts = new Alerts();
obAlerts.date = Date2.toString();
obAlerts.alertType = "Alert Type 1";
obAlerts.discription = "Some Text";
alert.add(obAlerts);
What I want to remove from them-
I want all alerts which have unique obAlerts.date and obAlerts.alertType. In other words, remove duplicate obAlerts.date and obAlerts.alertType alerts.
I tried this -
Alerts temp1, temp2;
String macTemp1, macTemp2, macDate1, macDate2;
for(int i=0;i<alert.size();i++)
{
temp1 = alert.get(i);
macTemp1=temp1.alertType.trim();
macDate1 = temp1.date.trim();
for(int j=i+1;j<alert.size();j++)
{
temp2 = alert.get(j);
macTemp2=temp2.alertType.trim();
macDate2 = temp2.date.trim();
if (macTemp2.equals(macTemp1) && macDate1.equals(macDate2))
{
alert.remove(temp2);
}
}
}
I also tried-
HashSet<Alerts> hs = new HashSet<Alerts>();
hs.addAll(obAlerts);
obAlerts.clear();
obAlerts.addAll(hs);

You need to specify yourself how the class decides equality by overriding a pair of methods:
public class Alert {
String date;
String alertType;
#Override
public boolean equals(Object o) {
if (this == 0) {
return true;
}
if ((o == null) || (!(o instanceof Alert)))
return false;
}
Alert alert = (Alert) o;
return this.date.equals(alert.date)
&& this.alertType.equals(alert.alertType);
}
#Override
public int hashCode() {
int dateHash;
int typeHash;
if (date == null) {
dateHash = super.hashCode();
} else {
dateHash = this.date.hashCode();
}
if (alertType == null) {
typeHash = super.hashCode();
} else {
typeHash = this.alertType.hashCode();
}
return dateHash + typeHash;
}
}
You can then loop through your ArrayList and add elements if they aren't already there as Collections.contains() makes use of these methods.
public List<Alert> getUniqueList(List<Alert> alertList) {
List<Alert> uniqueAlerts = new ArrayList<Alert>();
for (Alert alert : alertList) {
if (!uniqueAlerts.contains(alert)) {
uniqueAlerts.add(alert);
}
}
return uniqueAlerts;
}
However, after saying all that, you may want to revisit your design to use a Set or one of its family that doesn't allow duplicate elements. Depends on your project. Here's a comparison of Collections types

You could use a Set<>. By nature, Sets do no include duplicates. You just need to make sure that you have a proper hashCode() and equals() methods.

In your Alerts class, override the hashCode and equals methods to be dependent on the values of the fields you want to be primary keys. Afterwards, you can use a HashSet to store already seen instances while iterating over the ArrayList. When you find an instance which is not in the HashSet, add it to the HashSet, else remove it from the ArrayList. To make your life easier, you could switch to a HashSet altogether and be done with duplicates per se.
Beware that for overriding hashCode and equals, some constraints apply.
This thread has some helpful pointers on how to write good hashCode functions. An important lesson is that simply adding together all dependent fields' hashcodes is not sufficient because then swapping values between fields will lead to identical hashCodes which might not be desirable (compare swapping first name and last name). Instead, some sort of shifting-operation is usually done before adding the next atomic hash, eg. multiplying with a prime.

First store your datas in array then split at as one by one string,, till the length of that data execute arry and compare with acyual data by if condition and retun it,,
HashSet<String> hs = new HashSet<String>();
for(int i=0;i<alert.size();i++)
{
hs.add(alert.get(i).date + ","+ alert.get(i).alertType;
}
alert.clear();
String alertAll[] = null;
for (String s : hs) {
alertAll = s.split(",");
obAlerts = new Alerts();
obAlerts.date = alertAll[0];
obAlerts.alertType = alertAll[1];
alert.add(obAlerts);
}

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

android XML parse into Hash map not working

I am getting the most bizzarre behavior with trying to parse an XML, I run through it step by step and all values are assigned and retrieved in order and then the object I create is added to a HashMap for easy look up, the problem is when I am done retrieving it all the HashMap has null values and the ones that aren't null are the value of the very last node that was read, I have walked through it over and over and it all seems correct, but when it's done loading the values in the HasMap look like:
[0] null
[1] NarrationItem#44e9d170
[2] null
[3] null
[4] NarrationItem#44e9d170
etc, etc.
The format of my XML files is:
<narrations>
<narration id="0" name="A" alias="a" >
<line text="This is a test."></line>
</narration>
<narration id="1" name="B" alias="b" >
<line text="This another a test."></line>
</narration>
<narration id="2" name="C" alias="c" >
<line text="This is STILL a test."></line>
</narration>
</narrations>
And my XML parsing method is follows:
public HashMap<String, NarrationItem> NarrationMap = new HashMap<String, NarrationItem>();
private void LoadNarrationsXML() {
NarrationItem i = new NarrationItem();
String line;
String s;
try {
// Get the Android-specific compiled XML parser.
XmlResourceParser xmlParser = this.getResources().getXml(R.xml.narrations);
while (xmlParser.getEventType() != XmlResourceParser.END_DOCUMENT) {
if (xmlParser.getEventType() == XmlResourceParser.START_TAG) {
s = xmlParser.getName();
if (s.equals("narration")) {
i.Clear();
i.ID = xmlParser.getAttributeIntValue(null, "id", 0);
i.Name = xmlParser.getAttributeValue(null, "name");
i.Alias = xmlParser.getAttributeValue(null, "alias");
} else if (s.equals("line")) {
line = xmlParser.getAttributeValue(null, "text");
i.Narration.add(line);
}
} else if (xmlParser.getEventType() == XmlResourceParser.END_TAG) {
s = xmlParser.getName();
if (s.equals("narration")) {
NarrationMap.put(i.Alias, i);
}
}
xmlParser.next();
}
xmlParser.close();
} catch (XmlPullParserException xppe) {
Log.e(TAG, "Failure of .getEventType or .next, probably bad file format");
xppe.toString();
} catch (IOException ioe) {
Log.e(TAG, "Unable to read resource file");
ioe.printStackTrace();
}
}
The NarrationItem object is a custom object defined as:
public class NarrationItem {
int ID;
String Name;
String Alias;
ArrayList<String> Narration = new ArrayList<String>();
public NarrationItem() { }
public void LoadNarration(int id, String name, String alias, ArrayList<String> narration) {
ID = id;
Name = name;
Alias = alias;
Narration.addAll(narration);// = narration;
}
public void Clear() {
ID = 0;
Name = "";
Alias = "";
Narration.clear();
}
}//End Narration
If someone could point out the problem I'd be very thankful I have sat here staring at this issue for hours.

You're only ever creating one NarrationItem object - you're then using a reference to that object as the value for multiple entries in the map. Don't do that. You need to understand that the map doesn't contain an object as the value - it contains a reference to an object.
You can probably fix this just by creating a new NarrationItem each time instead of calling Clear.
It's not clear how you're looking at the map to see those null values, but if you're using the debugger and looking at the internal data structure, you probably shouldn't really be doing that either - instead, step through the keys, values or entries, i.e. stick within the abstraction that HashMap is meant to support.