Develop Reference

Why isn't Android Volley request working?

I simply trying to get JSON data from url (https://krokapp.by/api/rest/tags/?format=json):
RequestQueue mRequestQueue;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mRequestQueue = Volley.newRequestQueue(this);
String url = "https://krokapp.by/api/rest/tags/?format=json";
final JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null, response -> {
Log.d("krok_data", response.toString());
}, error -> {
Log.d("krok_data", "Error");
error.printStackTrace();
});
mRequestQueue.add(request);
}
However, when I try this with different JSON api, for example:
https://samples.openweathermap.org/data/2.5/weather?id=2172797&appid=b6907d289e10d714a6e88b30761fae22
everything works fine. Is there something wrong with the API I'm trying to get data from?

Since the ressource you are calling returns a JSON array, simply change the volley request type from JsonObectRequest to JsonArrayRequest.
Should look like this then:
RequestQueue mRequestQueue = Volley.newRequestQueue(this);
String url = "https://krokapp.by/api/rest/tags/?format=json";
final JsonArrayRequest request = new JsonArrayRequest(Request.Method.GET, url, null,
response -> Log.d("krok_data", response.toString()),
error -> {
Log.d("krok_data", "Error");
error.printStackTrace();
});
mRequestQueue.add(request);

Next Page Token is not functional and display only maximum (50) results

I am trying to fetch all videos of a channel using youtube data api, but my code is giving error and doesn't respond to PAGE token
displayVideos();
}
private void displayVideos ()
{
RequestQueue requestQueue= Volley.newRequestQueue(this);
StringRequest stringRequest=new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
try {
JSONObject jsonObject = new JSONObject(response);
System.out.println(jsonObject.get("nextPageToken"));
JSONArray jsonArray = jsonObject.getJSONArray("items");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject1 = jsonArray.getJSONObject(i);
if (jsonObject1.has("id")){
JSONObject jsonVideoId=jsonObject1.getJSONObject("id");
if (jsonVideoId.has("kind")){
if(jsonVideoId.getString("kind").equals("youtube#video")){
JSONObject jsonObjectSnippet = jsonObject1.getJSONObject("snippet");
JSONObject jsonObjectDefault=jsonObjectSnippet.getJSONObject("thumbnails").getJSONObject("medium");
String video_id=jsonVideoId.getString("videoId");
VideoDetails vd=new VideoDetails();
vd.setVideoId(video_id);
vd.setTitle(jsonObjectSnippet.getString("title"));
vd.setDescription(jsonObjectSnippet.getString("description"));
vd.setUrl(jsonObjectDefault.getString("url"));
videoDetailsoArrayList.add(vd);
}
// recyclerView.setAdapter(adapter);
// adapter.notifyDataSetChanged();
}
}
}
}catch (JSONException e) {
e.printStackTrace();
}
the url I am trying to parse is
String url="https://www.googleapis.com/youtube/v3/search?part=snippet&channelId=UCVMWWQ985A_-SESZUy_SsVQ&maxResults=50&pageToken="+nextPageToken+"&order=date&pageToken=CAUQAA&key=API_KEY";
I have been searchingb to apply nextpage token or page token in android studio but couldnt get specific tutorial. there are many examples but being naive in android studio I cant implement it into my code.

Please note that your URL does contain two instances of the parameter pageToken:
"https://www.googleapis.com/youtube/v3/search?part=snippet&channelId=UCVMWWQ985A_-SESZUy_SsVQ&maxResults=50&pageToken="+nextPageToken+"&order=date&pageToken=CAUQAA&key=API_KEY".
It should have only one for that to work OK; to be more precise, your URL should contain only this instance: pageToken="+nextPageToken+".
On the other hand, your code above does not show the loop implementing pagination. That is that you haven't shown the piece of code where you actually assign a valid value to the variable nextPageToken.
Therefore I cannot tell if your program will work or not.
The pagination loop would look like this:
// initially no pageToken
nextPageToken = null;
// URL as above, without the parameter pageToken
url = ...
do {
invoke the API on the URL: url + (nextPageToken != null ? "&pageToken=" + nextPageToken : "")
nextPageToken = jsonObject.get("nextPageToken");
} while (nextPageToken != null)

How to find specific data from a Volley Api string response

I am new to APIs and finally figured out how to successfully retrieve a request response from a website. The thing is I am completely lost on how I should handle the response. I don't know how to access certain values within the response
here is my API Volley code
RequestQueue requestQueue = Volley.newRequestQueue(this);
String uri = Uri.parse("https://chicken-coop.p.rapidapi.com/games/Fortnite?platform=pc")
.buildUpon()
.build().toString();
StringRequest stringRequest = new StringRequest(
Request.Method.GET, uri, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
displayResults.setText("Response: " + response.substring(0,500));
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
displayResults.setText( "" + error.toString());
}
}) {
#Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> params = new HashMap<>();
params.put("X-RapidAPI-Key", "5cdb2bbe57mshd9242c8d3177cb3p16f2fbjsnd7c5829eb4ad");
params.put("X-RapidAPI-Host", "chicken-coop.p.rapidapi.com");
return params;
}
};
requestQueue.add(stringRequest);
Here is the response query that I received
"result":{10 items
"title":"Fortnite"
"releaseDate":"Jul 25, 2017"
"description":"Epic Games next project has you building forts and stopping a zombie invasion."
"genre":[...
]6 items
"image":"https://static.metacritic.com/images/products/games/5/c7eb46ceb7da9c72c5a95193e8621faf-98.jpg"
"score":81
"developer":"Epic Games"
"publisher":[...
]1 item
"rating":"T"
"alsoAvailableOn":[6 items
0:
"iPhone/iPad"
1:
"PlayStation 3"
2:
"PlayStation 4"
3:
"Switch"
4:
"Xbox 360"
5:
"Xbox One"
How would I go about finding an explicit value from the response query? I have been searching for how to do this online and there are so many different ways to go about and I have no clue what to do. For example, how would I be able to put the Release Date into its own text box? Most of the examples I see online use JsonObjects when I m using a string response

in your onResponse method you need to parse your result so you can extract any data you want
public void onResponse(String response) {
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("result");
// toaccess to your json data
String title = jsonArray.getString("title");
// your code
} catch (JSONException e) {
e.printStackTrace();
}
}

org.json.JSONException: End of input at character 0 of

There is some issue with the JSONObjectRequest in Volley library to receive the JSON data. I suppose I am going wrong somewhere in receiving the JSON object in the Java code. Following is my JSON output coming as a response from the php file hosted on server:
{"workers":[
{"id":"1","name":"Raja","phonenumber":"66589952","occupation":"Plumber","location":"Salunke Vihar","rating":"4","Review":"Hard Worker","price":"80"},
{"id":"2","name":"Aman","phonenumber":"789456","occupation":"Plumber","location":"Wakad","rating":"4","Review":"Good","price":"80"}
],
"success":1}
Following is clode from the Java file where I am using the JSON request using Volley library:
JsonObjectRequest jsonRequest = new JsonObjectRequest (Request.Method.POST, url,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
// I should receive the success value 1 here
int success = response.getInt("success");
//and should receive the workers array here
Log.d("response",response.getJSONArray("workers").toString());
Log.d("success",""+success);
} catch (JSONException e) {
e.printStackTrace();
}
Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_LONG).show();
recyclerView = (RecyclerView) findViewById(R.id.recyclerView);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(getApplicationContext());
recyclerView.setLayoutManager(layoutManager);
//Finally initializing our adapter
adapter = new WorkerAdapter(listWorkers);
recyclerView.setAdapter(adapter);
//adapter is working fine
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.d("error",error.toString());
Toast.makeText(getApplicationContext(),error.toString(),Toast.LENGTH_LONG).show();
}
}){
#Override
protected Map<String,String> getParams(){
Map<String,String> params = new HashMap<String, String>();
params.put("tag", "get_list");
params.put("service", service);
return params;
}
Running the above code it goes to the error listener and gives the output as org.json.JSONException: End of input at character 0 of.
But if I use StringRequest in place of JsonObjectRequest and receive the JSON response as a string then I am able to receive the output as a String but I can't use it further. So, please let me know where I am going wrong in receiving the JSONdata and suggest me the changes in the code that I must do.
EDIT- I am adding the php file which is returning the JSON object. Please let me know if there is some error over here:
<?php
error_reporting(0);
include("config.php");
if($_SERVER['REQUEST_METHOD']=='POST'){
$tag = $_POST['tag'];
// array for JSON response
$response = array();
if ($tag == 'get_list') {
// Request type is check Login
$service = $_POST['service'];
//echo json_encode($service);
// get all items from myorder table
$result = mysql_query("SELECT * FROM Workers WHERE Occupation = '$service'") or die(mysql_error());
if (mysql_num_rows($result) > 0) {
$response["workers"] = array();
while ($row = mysql_fetch_array($result)) {
// temp user array
$item = array();
$item["id"] = $row["wID"];
$item["pic"] = $row["Pic"];
$item["name"] = $row["Name"];
$item["phonenumber"] = $row["Phone Number"];
$item["occupation"] = $row["Occupation"];
$item["location"] = $row["Location"];
$item["rating"] = $row["Rating"];
$item["Review"] = $row["Review"];
$item["price"] = $row["Price"];
// push ordered items into response array
array_push($response["workers"], $item);
}
// success
$response["success"] = 1;
}
else {
// order is empty
$response["success"] = 0;
$response["message"] = "No Items Found";
}
}
echo json_encode($response);
}
?>

When I ran the api end point I have got the following result instead of the one that you have been telling so. So stop giving irrelevant data.
"Plumber"{"workers":[{"id":"1","pic":"ttp:\/\/vorkal.com\/images\/vorkal_cover.PNG","name":"Raja","phonenumber":"66589952","occupation":"Plumber","location":"Salunke Vihar","rating":"4","Review":"Hard Worker. Very Professional.","price":"80"},{"id":"2","pic":"http:\/\/vorkal.com\/images\/vorkal_cover.PNG","name":"Aman","phonenumber":"789456","occupation":"Plumber","location":"Wakad","rating":"4","Review":"Good","price":"80"}],"success":1}
Where Plumber is not the tag at all, hence throws error as the same is not valid json string. There's error in your server side scripting. I request you to send the complete script without modification.
If you are not getting the JSONObject that means the following is a malformed json. Thus you can try the following code in server side
function utf8ize($d) {
if (is_array($d)) {
foreach ($d as $k => $v) {
$d[$k] = $this->utf8ize($v);
}
} else if (is_string ($d)) {
return utf8_encode($d);
}
return $d;
}
where$d is the string/response. use it as echo json_encode($this->utf8ize($detail));
Also try the following in client side code
Gson gson = new Gson();
JsonReader reader = new JsonReader(new StringReader(result1));
reader.setLenient(true);
You may refer the solution to this question here click here

you can use Gson to convert json string to object
Gson gson = new Gson();
GetWorkersResponse getWorkersResponse =gson.fromJson(response,GetWorkersResponse.class);
class GetWorkersResponse {
public boolean success;
public List<Worker> workers = new ArryList<>();
}
It's work for me.

Can you check that server is returning you a JSONObject and not the string? In Volley if the type of response is different then it will return the error.

How to receive data from web asynchronous and use the result string in the next line of code?

I want to get some JSON code from my API. I wish to do something like this in the OnCreate:
try
{
String jsonstr = getSomeThingAndPauseAndroid("http://someplace.com/api/xyz");
if (!jsonstr.isEmpty()) JSONObject jsonobj = new JSONObject(jsonstr);
}
catch { // handle error }
But when it happens, Android just go doing stuff and don't wait for the request to complete and response and I get nothing on jsonstr.
Is there some way to do that not needing a lot of new class files?

The correct way to do this is to make the request asynchronously and trigger a method on response. This is an example using Google's Volley:
//Start volley:
RequestQueue queue = Volley.newRequestQueue(this); // this = context
final String url = "http://someplace.com/api/xyz"";
// prepare the Request
JsonObjectRequest getRequest = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>()
{
#Override
public void onResponse(JSONObject response) {
//This is where you setup your UI
//Remember to dismiss the ProgressDialog
}
},
new Response.ErrorListener()
{
#Override
public void onErrorResponse(VolleyError error) {
//Remember to dismiss the ProgressDialog
Log.d("Error.Response", response);
}
}
);
// add it to the RequestQueue
//Here you should add a ProgressDialog so the user knows to wait
queue.add(getRequest);