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How to store response in a variable in Volley?

I Want to Store the response of Volley in a Public variable but when I Toast it out the volley request that returns null
public JSONArray array ;
String URL = "http://192.168.1.104/json.php";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_json);
array = new JSONArray();
JsonArrayRequest request = new JsonArrayRequest( URL,new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
try {
array = response;
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
Volley.newRequestQueue(this).add(request);
Toast.makeText(json.this, array.toString(),Toast.LENGTH_LONG).show();

As people have said, calling the Toast initiation within onResponse() works, but the best way to handle this is to create a small listener interface or method that is called in onResponse and implemented where you need it.
I'd also strongly suggest only passing the data you need and saving that in a model class, rather than just saving the response outright.
a very simple example would be
String URL = "http://192.168.1.104/json.php";
// make sure your class implements this
public interface ResponseListener {
public gotResponse(JSONArray array);
}
// implementation of ResponseListener
public gotResponse(JSONArray array) {
// eventually do more with this data
Toast.makeText(json.this, array.toString(),Toast.LENGTH_LONG).show();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_json);
ResponseListener listener = this;
JsonArrayRequest request = new JsonArrayRequest( URL,new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
try {
listener.gotResponse(response);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
Volley.newRequestQueue(this).add(request);

One way could be moving the line:
Toast.makeText(json.this, array.toString(),Toast.LENGTH_LONG).show();
exactly to the line after: array = response;

Android Async Tsk not Executing Properly

I just want to wait in a splash screen until my JSON is processing, but that is not happening. TheonPostExecute() method is executed just after doinbackground(). There is no time to load the whole JSON.
Here is my code. I am getting List size zero first then JSON will start to load.
private class GetContacts extends AsyncTask<Void, Void, Void> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected Void doInBackground(Void... arg0) {
datalist = new ArrayList<>();
Log.e("entering","Enter Inside");
try{
JsonArrayRequest billionaireReq =
new JsonArrayRequest(new ApiURLs().getAll_movies_url()
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
Log.e("response", "Response" + response);
//Initialize Gson obj to process jason response
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
// assigning data in model class, we initializing this class as a array type
// because the response is in array format
HomeModel[] getResult = gson.fromJson(response.toString(), HomeModel[].class);
// this loop help us in fetching all the records of model class
for (int i = 0; i < getResult.length; i++) {
Log.e("response", "Model Values" + getResult[i].toString());
//datalist.add(getResult[i]);
datalist.add(getResult[i]);
}
//GlobalData.setGlobal_movie_list(datalist);
Log.e("DataLoded","Record Added");
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.e("Request","Error" + error);
}
});
//This is a queue which is used by Volley to lineup requests
AppController.getInstance().addToRequestQueue(billionaireReq);
}
catch (Exception e){
Log.e("Error","Error"+e);
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
Log.e("Data","DataSize"+datalist.size());
}
}

Java Interface Callback on Android

I am currently trying to make an android app that basically downloads strings from a url. But I want to make it object oriented. My mainActivity gets string from webService which downloads string when button is clicked. But I am not good at interfaces and callbacks. What should I do to make this code run?
public class MainActivity extends Activity implements WebServiceInterface{
private TextView textView;
private Button readWebPage;
private WebService service;
private WebServiceInterface webServiceInterface;
private String response;
/**
* Called when the activity is first created.
*/
#Override
public void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.TextView01);
readWebPage = (Button) findViewById(R.id.readWebpage);
service = new WebService();
readWebPage.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
service.execute(new String[]{"http://google.com/"});
onSuccess(response);
}
});
}
#Override
public void onSuccess(String response) {
textView.setText(Html.fromHtml(response));
}
#Override
public void onFail(Exception ex) {
textView.setText(ex.getLocalizedMessage());
}
}
public class WebService extends AsyncTask<String, Void, String> {
private WebServiceInterface webServiceInterface;
#Override
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(
new InputStreamReader(content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
webServiceInterface.onSuccess(response);
} catch (Exception e) {
e.printStackTrace();
webServiceInterface.onFail(e);
}
}
return response;
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
}
}
public interface WebServiceInterface {
void onSuccess(String response);
void onFail(Exception ex);
}

you need to create one public method for set webServiceInterface in WebService class like
public setWebServiceInterface (WebServiceInterface listener)
{
this.webServiceInterface =listener;
}
in MainActivity activity call this method and pass argument this
service.setWebServiceInterface (this);
in WebService class in onPostExecute Method call
webServiceInterface.onSuccess(s);

Add WebService (WebServiceInterface webServiceInterface) in your AsyncTask as a constructor.
service = new WebService(new WebServiceInterface (){
void onSuccess(String response){
//do your stuff
}
void onFail(Exception ex){
//do your stuff
}
});
and in your asynctask
public class WebService extends AsyncTask<String, Void, String> {
public WebService (WebServiceInterface webServiceInterface){
this.webinterface= webServiceInterface;
}
private WebServiceInterface webinterface;
#Override
protected String doInBackground(String... urls) {
String response = "";
for (String url : urls) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(url);
try {
HttpResponse execute = client.execute(httpGet);
InputStream content = execute.getEntity().getContent();
BufferedReader buffer = new BufferedReader(
new InputStreamReader(content));
String s = "";
while ((s = buffer.readLine()) != null) {
response += s;
}
webinterface.onSuccess(response);
} catch (Exception e) {
e.printStackTrace();
webinterface.onFail(e);
}
}
return response;
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
}
}

I have found the problem, it is because of runOnUiThread is missing.

Networking with Volley

Please could you help me with a network request I am trying here.
I have 2 Classes Network.class and MainActivity.class. I have a TextView in the MainActivity Class that I would like to be replaced with the text I get from the Network call in the Network Class. Problem I am currently having is I cant initiate the network call in the Network Class when the MainActivity Class is loaded when the application starts?
Below is the Code to MainActivity:
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView tv = (TextView)findViewById(R.id.text);
String test = Network.userName;
tv.setText(test);
}
}
and below is the network class that I would like to do the network call and the response will need to replace the text in the TextView in the MainActivity Class.
Network Class:
public class Network extends Activity{
public static String userName;
private String jsonResponse;
String url_home = "http://www.someurl.com";
private void postData(final TextView tv) {
final RequestQueue request = Volley.newRequestQueue(this);
JsonObjectRequest postReq = new JsonObjectRequest(Request.Method.GET, url_home, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
try {
jsonResponse = "";
for(int i = 0; i< response.length(); i++) {
String userName = response.getString("DOTWBannerHD");
System.out.println("++++++++++++++++++++++++++++++++++++++++++++userName = " + userName);
jsonResponse += userName;
System.out.println("++++++++++++++++++++++++++++++++++++++++++++JsonResponse = " + jsonResponse);
}
tv.setText(jsonResponse);
} catch (JSONException e){
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
System.out.println("Error [" + error + "]");
}
}) {
#Override
public Map getHeaders() throws AuthFailureError {
Map headers = new HashMap();
headers.put("Accept", "application/json");
System.out.println(headers);
return headers;
}
};
request.add(postReq);
}
}
I am very new to Android and am battling to call the postData method from the second activity, in the MainActivity? The issue I get is that the TextView has text hard coded in the XML but when I run the Application it is blank? It's like, either the response is blank, but I doubt its that because the code I put in the Network Class (System.out.println("++++++++++++++++++++++++++++++++++++++++++++userName = " + userName);) isn't showing up in the Terminal which makes me think that its not running the postData method at all or the response is not working but it just sets the TextView to blank?

You cannot change the GUI from an async-task.
As JsonObjectRequest works asynchronous you should run tv.setText(jsonResponse); on the main thread using:
runOnUiThread(new Runnable() {
public void run() {
tv.setText(jsonResponse);
}
});

Following up on my comment, the reason your are not seeing anything in the terminal is because you're not calling you postData method so it's never executed.
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView tv = (TextView)findViewById(R.id.text);
Network network = new Network();
network.postData(tv);
}
}
and make Network a normal class not an Activity.
public class Network{
////The variables and your postData method here
}

Get Android Volley response in another class

I'm trying to use Volley as a DBA layer to call a webservice that hadles JSON objects. Because this layer is below the activity and another service layer, it doesn't seem to be working properly. I'll try to explain my setup:
MainActivity:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ProductService productService = new ProductService();
productService.getProduct();
}
ProductService.java:
public void getProduct() {
JsonObjectRequest req = new JsonObjectRequest("http://echo.jsontest.com/name/Milk/price/1.23/", null, createMyReqSuccessListener(), createMyReqErrorListener());
ApplicationController.getInstance().addToRequestQueue(req);
}
private Response.Listener<JSONObject> createMyReqSuccessListener() {
return new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
Log.v("response", response.toString());
}
};
}
private Response.ErrorListener createMyReqErrorListener() {
return new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
return;
}
};
}
I hope that is clear enough.
In the end, I would like to use the ProductService::getProduct() from an activity and the the actual JSON response from the webservice in a variable which I can later use.
However, at the moment, the line
Log.v("response", response.toString());
doesn't even execute. What am I doing wrong?

What I would try is this:
Declare getProduct as
public void getProduct(Response.Listener<JSONObject> listener,
Response.ErrorListener errlsn) {
JsonObjectRequest req = new JsonObjectRequest("http://echo.jsontest.com/name/Milk/price/1.23/",null, listener, errlsn);
ApplicationController.getInstance().addToRequestQueue(req);
}
And than call in your activity like this:
productService.getProduct(
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
variableFromActivity = response;
//Or call a function from the activity, or whatever...
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
//Show error or whatever...
}
});

Create an abstract class AppActivity
import androidx.appcompat.app.AppCompatActivity;
public abstract class AppActivity extends AppCompatActivity
{
abstract void callback(String data);
}
Extend all your Activities using AppActivity
public class MainActivity extends AppActivity
{
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String url = "Your URL";
JSONObject jsonBody = new JSONObject();
try {
jsonBody.put("Title", "Android Volley Demo");
jsonBody.put("Author", "BNK");
}
catch (JSONException e) {
System.out.println(e);
}
final String requestBody = jsonBody.toString();
Messenger messenger = new Messenger(MainActivity.this);
messenger.sendMessage(this, url, requestBody);
}
public void callback(String data)
{
System.out.println(data);
}
}
Create Messenger class as below:
public class Messenger
{
private AppActivity myActivity;
public Messenger(AppActivity activity)
{
myActivity = activity;
}
public void sendMessage(Context context, String url, final String requestBody)
{
// Instantiate the RequestQueue.
RequestQueue queue = Volley.newRequestQueue(context);
// Request a string response from the provided URL.
StringRequest stringRequest =
new StringRequest(
Request.Method.POST,
url,
null,
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
System.out.println(error);
}
}
) {
#Override
public String getBodyContentType() {
return "application/json; charset=utf-8";
}
#Override
public byte[] getBody() throws AuthFailureError {
try {
return requestBody == null ? null : requestBody.getBytes("utf-8");
}
catch (UnsupportedEncodingException uee) {
VolleyLog.wtf("Unsupported Encoding while trying to get the bytes of %s using %s", requestBody, "utf-8");
return null;
}
}
#Override
protected Response<String> parseNetworkResponse(NetworkResponse response)
{
myActivity.callback(new String(response.data));
String responseString = "";
if (response != null) {
responseString = String.valueOf(response.statusCode);
// can get more details such as response.headers
}
return Response.success(responseString, HttpHeaderParser.parseCacheHeaders(response));
}
};
queue.add(stringRequest);
}
}
Hope it helps.