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Final object losing attribute value after function call

I am trying to properly handle Volley responses in my Android application, which loads some items from a database. Volley functions are encapsulated in the WebRequester class:
public class WebRequester extends Application {
public static final String TAG = WebRequester.class.getSimpleName();
private RequestQueue mRequestQueue;
private static WebRequester mInstance;
public WebRequester() {
mInstance = this;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
public static synchronized WebRequester getInstance() {
return mInstance;
}
public <T> void addToRequestQueue(Request<T> req) {
req.setTag(TAG);
getRequestQueue().add(req);
}
/* ... */
}
Another class, ItemsController, centralizes the requests to be created. In order to get the response code, I created a nested class, VolleyCallback, and set its attribute responseCode inside an overriden parseNetworkResponse() call:
public class FeedItemsController extends Application {
private String URL_GET_FEED_ITEMS = /* My URL */;
private static final String TAG = FeedItemsController.class.getSimpleName();
private ArrayList<FeedItem> feedItems;
public class VolleyRequestCallback {
public int responseCode;
public int getResponseCode() {
return responseCode;
}
public void setResponseCode(int responseCode) {
this.responseCode = responseCode;
}
}
public void loadItems() {
final VolleyRequestCallback callback = new VolleyRequestCallback();
if (feedItems == null) {
feedItems = new ArrayList<>();
Cache cache = WebRequester.getInstance().getRequestQueue().getCache();
Cache.Entry entry = cache.get(URL_GET_FEED_ITEMS);
if (entry != null) {
try {
String data = new String(entry.data, "UTF-8");
parseJsonFeed(new JSONObject(data));
} catch (JSONException | IOException e) {
e.printStackTrace();
}
}
else {
JsonObjectRequest jsonReq = new JsonObjectRequest(Request.Method.GET, URL_GET_FEED_ITEMS, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
VolleyLog.d(TAG, "Response: " + response.toString());
parseJsonFeed(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
}
}
) {
#Override
protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
callback.setResponseCode(response.statusCode);
System.out.println("Code 1 = " + response.statusCode);
return super.parseNetworkResponse(response);
}
};
WebRequester.getInstance().addToRequestQueue(jsonReq);
}
}
System.out.println("Code 2 = " + callback.getResponseCode());
}
/* ... */
}
Then method loadItems() is called from another class. The issue is - when it enters the parseNetworkResponse() method, the resultCode is correctly set to, let's say, 200. However, when I try to reuse it outside the request overriding, it's 0 again:
Code 1 = 200
Code 2 = 0
It might be a bad implementation of a response handling, but my main question is why is the object attribute changed?
Thanks in advance

It turned out to be a not exciting bug. The call to parseNetworkResponse is asynchronous, meaning that when the first print is performed, the server had not responded yet.

Unity Android Get Google Play Advertising ID

I'm attempting to get the google play advertising ID in Unity but it doesn't seem to be working at all.
Here's the code I'm using that I've found in a couple SO's like this one:
AndroidJavaClass up = new AndroidJavaClass ("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = up.GetStatic<AndroidJavaObject> ("currentActivity");
AndroidJavaClass client = new AndroidJavaClass ("com.google.android.gms.ads.identifier.AdvertisingIdClient");
AndroidJavaObject adInfo = client.CallStatic<AndroidJavaObject> ("getAdvertisingIdInfo",currentActivity);
advertisingID = adInfo.Call<string> ("getId").ToString();
using(AndroidJavaClass pluginClass = new AndroidJavaClass("example.com.Toast")) {
if(pluginClass != null) {
toastClass = pluginClass.CallStatic<AndroidJavaObject>("getInstance");
activityContext.Call("runOnUiThread", new AndroidJavaRunnable(() => {
toastClass.Call("toastMessage", advertisingID);
}));
}
}
I have to do this on an actual device and haven't found a good way to actually log anything save a Toast message, which doesn't display anything here. But if I do this (which gets the android device ID) the toast displays just fine.
AndroidJavaClass up = new AndroidJavaClass ("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = up.GetStatic<AndroidJavaObject> ("currentActivity");
AndroidJavaObject contentResolver = currentActivity.Call<AndroidJavaObject> ("getContentResolver");
AndroidJavaClass secure = new AndroidJavaClass ("android.provider.Settings$Secure");
string android_id = secure.CallStatic<string> ("getString", contentResolver, "android_id");
Any idea what I should be doing to get the Google Play Advertising ID?
I've also tried doing it within the jar code itself natively like this:
AsyncTask<Void, Void, String> task = new AsyncTask<Void, Void, String>() {
#Override
protected String doInBackground(Void... params) {
AdvertisingIdClient.Info idInfo = null;
try {
idInfo = AdvertisingIdClient.getAdvertisingIdInfo(ToastCLass.getInstance().context);
} catch (GooglePlayServicesNotAvailableException e) {
e.printStackTrace();
} catch (GooglePlayServicesRepairableException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
String advertId = null;
try{
advertId = idInfo.getId();
}catch (NullPointerException e){
e.printStackTrace();
}
return advertId;
}
#Override
protected void onPostExecute(String advertId) {
Toast.makeText(ToastClass.getInstance().context, advertId, Toast.LENGTH_LONG).show();
}
};
task.execute();
But that just causes an error on my app when it runs (I think because it's trying to run the AsyncTask on the UI thread?). Again hard, as I haven't really found a way to display the logs/errors.
It seems if I run my app on an emulator I can get to a log, which does help with logging out the info.

I know this answer is a bit late, but this may be helpful for someone who is facing this issue.
First of all the answer given by Tom is correct, it works. But the reason why this error occurs is, when we add aar file of a package, we are not including all the dependencies it has. You can actually do that by checking the pom file.
So in here, to avoid this error, you can just add play-services-ads-identifier-16.0.0.aar package along with play-service-ads.
You can find this package in here

I ended up writing a custom class to access this, since the error was:
Caused by: java.lang.ClassNotFoundException: Didn't find class "com.google.android.gms.ads.identifier.AdvertisingIdClient"
Here's the class I wrote:
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.content.pm.PackageManager;
import android.os.IBinder;
import android.os.IInterface;
import android.os.Looper;
import android.os.Parcel;
import android.os.RemoteException;
import java.io.IOException;
import java.util.concurrent.LinkedBlockingQueue;
public final class AdvertisingIdClientInfo {
public static final class AdInfo {
private final String advertisingId;
private final boolean limitAdTrackingEnabled;
AdInfo(String advertisingId, boolean limitAdTrackingEnabled) {
this.advertisingId = advertisingId;
this.limitAdTrackingEnabled = limitAdTrackingEnabled;
}
public String getId() {
return this.advertisingId;
}
public boolean isLimitAdTrackingEnabled() {
return this.limitAdTrackingEnabled;
}
}
public static AdInfo getAdvertisingIdInfo(Context context) throws Exception {
if(Looper.myLooper() == Looper.getMainLooper()) throw new IllegalStateException("Cannot be called from the main thread");
try { PackageManager pm = context.getPackageManager(); pm.getPackageInfo("com.android.vending", 0); }
catch (Exception e) { throw e; }
AdvertisingConnection connection = new AdvertisingConnection();
Intent intent = new Intent("com.google.android.gms.ads.identifier.service.START");
intent.setPackage("com.google.android.gms");
if(context.bindService(intent, connection, Context.BIND_AUTO_CREATE)) {
try {
AdvertisingInterface adInterface = new AdvertisingInterface(connection.getBinder());
AdInfo adInfo = new AdInfo(adInterface.getId(), adInterface.isLimitAdTrackingEnabled(true));
return adInfo;
} catch (Exception exception) {
throw exception;
} finally {
context.unbindService(connection);
}
}
throw new IOException("Google Play connection failed");
}
private static final class AdvertisingConnection implements ServiceConnection {
boolean retrieved = false;
private final LinkedBlockingQueue<IBinder> queue = new LinkedBlockingQueue<IBinder>(1);
public void onServiceConnected(ComponentName name, IBinder service) {
try { this.queue.put(service); }
catch (InterruptedException localInterruptedException){}
}
public void onServiceDisconnected(ComponentName name){}
public IBinder getBinder() throws InterruptedException {
if (this.retrieved) throw new IllegalStateException();
this.retrieved = true;
return (IBinder)this.queue.take();
}
}
private static final class AdvertisingInterface implements IInterface {
private IBinder binder;
public AdvertisingInterface(IBinder pBinder) {
binder = pBinder;
}
public IBinder asBinder() {
return binder;
}
public String getId() throws RemoteException {
Parcel data = Parcel.obtain();
Parcel reply = Parcel.obtain();
String id;
try {
data.writeInterfaceToken("com.google.android.gms.ads.identifier.internal.IAdvertisingIdService");
binder.transact(1, data, reply, 0);
reply.readException();
id = reply.readString();
} finally {
reply.recycle();
data.recycle();
}
return id;
}
public boolean isLimitAdTrackingEnabled(boolean paramBoolean) throws RemoteException {
Parcel data = Parcel.obtain();
Parcel reply = Parcel.obtain();
boolean limitAdTracking;
try {
data.writeInterfaceToken("com.google.android.gms.ads.identifier.internal.IAdvertisingIdService");
data.writeInt(paramBoolean ? 1 : 0);
binder.transact(2, data, reply, 0);
reply.readException();
limitAdTracking = 0 != reply.readInt();
} finally {
reply.recycle();
data.recycle();
}
return limitAdTracking;
}
}
}
And then accessing it:
public void methodName(final Activity context) {
new Thread(new Runnable() {
public void run() {
try {
AdvertisingIdClientInfo.AdInfo adInfo = AdvertisingIdClientInfo.getAdvertisingIdInfo(context);
this._googleAdvertiserId = adInfo.getId();
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
Then wrapped that up in a jar, and in Unity you can call it:
if (activityContext == null) {
using(AndroidJavaClass activityClass = new AndroidJavaClass("com.unity3d.player.UnityPlayer")) {
activityContext = activityClass.GetStatic<AndroidJavaObject>("currentActivity");
}
}
using(AndroidJavaClass pluginClass = new AndroidJavaClass("example.com.Class")) {
if(pluginClass != null) {
className = pluginClass.CallStatic<AndroidJavaObject>("getInstance");
activityContext.Call("runOnUiThread", new AndroidJavaRunnable(() => {
className.Call("methodName", activityContext);
}));
}
}

How to create a proper Volley Listener for cross class Volley method calling

I aim to call Volley from another class in, a very succinct, modular way ie:
VolleyListener newListener = new VolleyListener();
VolleySingleton.getsInstance().somePostRequestReturningString(getApplicationContext(), newListener);
JSONObject data = newListener.getResponse();
But am having allot of trouble getting the listener portion to work so as to be able to access the resulting data from a method such as
newListener.getResponse();
There are a few questions on this site that generally outline how to set up a volley call from another class, such as: Android Volley - How to isolate requests in another class. I have had success getting the method call to work, but to now get that data into the present class for usage has caused trouble.
I have the action within my VolleySingleton class as:
public void somePostRequestReturningString(final Context context,final VolleyListener<String> listener) {
final String URL = "http://httpbin.org/ip";
JsonObjectRequest set = new JsonObjectRequest(Request.Method.GET, URL, ((String) null),
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
listener.outPut = response.toString();
//Toast.makeText(context, response.toString(), Toast.LENGTH_LONG).show();
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.d("Error.Response", error.toString());
}
}
);
mRequestQueue.add(set);
}
and within the listener class:
public class VolleyListener {
public static String outPut;
private static Response.Listener<String> createSuccessListener() {
return new Response.Listener<String>() {
#Override
public void onResponse(String response) {
outPut = response;
}
};
}
}
How can I configure this to work and allow Volley calls and data retrieval from another class, particularly how to build callbacks correctly?

For your requirement, I suggest you refer to my following solution, hope it's clear and helpful:
First is the interface:
public interface VolleyResponseListener {
void onError(String message);
void onResponse(Object response);
}
Then inside your helper class (I name it VolleyUtils class):
public static void makeJsonObjectRequest(Context context, String url, final VolleyResponseListener listener) {
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
(url, null, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
listener.onResponse(response);
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
listener.onError(error.toString());
}
}) {
#Override
protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
try {
String jsonString = new String(response.data,
HttpHeaderParser.parseCharset(response.headers, PROTOCOL_CHARSET));
return Response.success(new JSONObject(jsonString),
HttpHeaderParser.parseCacheHeaders(response));
} catch (UnsupportedEncodingException e) {
return Response.error(new ParseError(e));
} catch (JSONException je) {
return Response.error(new ParseError(je));
}
}
};
// Access the RequestQueue through singleton class.
VolleySingleton.getInstance(context).addToRequestQueue(jsonObjectRequest);
}
Then, inside your Activity classes, you can call like the following:
VolleyUtils.makeJsonObjectRequest(mContext, url, new VolleyResponseListener() {
#Override
public void onError(String message) {
}
#Override
public void onResponse(Object response) {
}
});
You can refer to the following questions for more information (as I told you yesterday):
Android: How to return async JSONObject from method using Volley?
POST Request Json file passing String and wait for the response Volley
Android/Java: how to delay return in a method

Volley excels at RPC-type operations used to populate a UI, such as
fetching a page of search results as structured data. It integrates
easily with any protocol and comes out of the box with support for raw
strings, images, and JSON. By providing built-in support for the
features you need, Volley frees you from writing boilerplate code and
allows you to concentrate on the logic that is specific to your app.
How to create Common GET/POST Method Using Volley .
Create a Application Class
The Application class in Android is the base class within an Android
app that contains all other components such as activities and services
public class MyApplication extends Application {
public static final String TAG = MyApplication.class
.getSimpleName();
private RequestQueue mRequestQueue;
private static MyApplication mInstance;
#Override
public void onCreate() {
super.onCreate();
mInstance = this;
}
public static synchronized MyApplication getInstance() {
return mInstance;
}
public RequestQueue getRequestQueue() {
if (mRequestQueue == null) {
mRequestQueue = Volley.newRequestQueue(getApplicationContext());
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req, String tag) {
// set the default tag if tag is empty
req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
getRequestQueue().add(req);
}
public <T> void addToRequestQueue(Request<T> req) {
req.setTag(TAG);
getRequestQueue().add(req);
}
public void cancelPendingRequests(Object tag) {
if (mRequestQueue != null) {
mRequestQueue.cancelAll(tag);
}
}
}
Make Sure you add this Manifest Section .
<application
.....
android:name=".MyApplication"
>
Now, You need to create Singleton Class .
Singleton Pattern says that just define a class that has only one
instance and provides a global point of access to it .
public class MySingleton
{
private static MySingleton mInstance;
private RequestQueue mRequestQueue;
private static Context mCtx;
private MySingleton(Context context)
{
mCtx = context;
mRequestQueue = getRequestQueue();
}
public static synchronized MySingleton getInstance(Context context)
{
if (mInstance == null)
{
mInstance = new MySingleton(context);
}
return mInstance;
}
public RequestQueue getRequestQueue()
{
if (mRequestQueue == null)
{
mRequestQueue = Volley.newRequestQueue(mCtx.getApplicationContext());
}
return mRequestQueue;
}
public <T> void addToRequestQueue(Request<T> req)
{
getRequestQueue().add(req);
}
}
Now Common Class
public class VolleyUtils {
public static void GET_METHOD(Context context, String url, final VolleyResponseListener listener)
{
// Initialize a new StringRequest
StringRequest stringRequest = new StringRequest(
Request.Method.GET,
url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
listener.onResponse(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
listener.onError(error.toString());
}
})
{
};
// Access the RequestQueue through singleton class.
MySingleton.getInstance(context).addToRequestQueue(stringRequest);
}
public static void POST_METHOD(Context context, String url,final Map<String,String> getParams, final VolleyResponseListener listener)
{
// Initialize a new StringRequest
StringRequest stringRequest = new StringRequest(
Request.Method.POST,
url,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
listener.onResponse(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
listener.onError(error.toString());
}
})
{
/**
* Passing some request headers
* */
#Override
public Map<String, String> getHeaders() throws AuthFailureError {
HashMap<String, String> headers = new HashMap<String, String>();
getParams.put("Content-Type", "application/json; charset=utf-8");
return headers;
}
};
// Access the RequestQueue through singleton class.
MySingleton.getInstance(context).addToRequestQueue(stringRequest);
}
}
Now You should create Interface .
A class implements an interface, thereby inheriting the abstract
methods of the interface .
/**
* Created by Intellij Amiyo on 10-06-2017.
* Please follow standard Java coding conventions.
* http://source.android.com/source/code-style.html
*/
public interface VolleyResponseListener {
void onError(String message);
void onResponse(Object response);
}
How To Call
public void _loadAPI()
{
//GET
String URL_GET = "";
VolleyUtils.GET_METHOD(MainActivity.this, URL_GET, new VolleyResponseListener() {
#Override
public void onError(String message) {
System.out.println("Error" + message);
}
#Override
public void onResponse(Object response) {
System.out.println("SUCCESS" + response);
}
});
//POST
String URL_POST=" ";
VolleyUtils.POST_METHOD(MainActivity.this, URL_POST,getParams(), new VolleyResponseListener() {
#Override
public void onError(String message) {
System.out.println("Error" + message);
}
#Override
public void onResponse(Object response) {
System.out.println("SUCCESS" + response);
}
});
}
public Map<String,String> getParams()
{
Map<String, String> params = new HashMap<String, String>();
params.put("YOUR_KEY", "VALUE");
return params;
}
For demo you should Download Volley-Common-Method

If you followed the general example from Android Volley - How to isolate requests in another class, (including the stuff regarding the singleton stuff) and looking for the parsing part (or, how to actually use the objects you receive), then this is the (again very general) addition
say you have a Json object coming in, that looks somewhat like this :
{"users":
[{"username":"Jon Doe","userid":83},
{"username":"Jane Doe",userid":84}]}
and our User object would look something like this:
public class User
{
String username;
int userid;
public String getName()
{
return username;
}
public int getId()
{
return userid;
}
}
Important: When working with Gson (you will see later), the object
fields should be named according to params you get in the Json, this
sort of reflection is how the parsing works.
then, the request itself would look something like this
(note the listener callback returning a
List<User>
object back to the caller, you'll see later):
public class NetworkManager
{
//... other stuff
public void getUsers(final SomeCustomListener<List<User>> listener)
{
final String URL = "http://httpbin.org/ip";
StringRequest request = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>()
{
#Override
public void onResponse(String response)
{
Log.d(TAG + ": ", "getUsers Response: " + response);
List<User> users = MyJsonParser.getListObjects(response, "$.users[*]", User.class);
if(null != users)
listener.getResult(users);
}
},
new Response.ErrorListener()
{
#Override
public void onErrorResponse(VolleyError error)
{
if (null != error.networkResponse)
{
Log.d(TAG + ": ", "Error Response code: " + error.networkResponse.statusCode);
listener.getResult(null);
}
}
});
requestQueue.add(request);
// ... other stuff
}
what you would need now is that class to parse the Json string, namely the object list, in this example I use Gson (again - this is a general example, change and reorder stuff according to your needs, you could probably also optimize this some more - it's just for the explanation):
public class MyJsonParser
{
//... other stuff
public static <T> List<T> getListObjects(String json_text, String json_path, Class<T> c)
{
Gson gson = new Gson();
try
{
List<T> parsed_list = new ArrayList<>();
List<Object> nodes = JsonPath.read(json_text, json_path);
for (Object node : nodes)
{
parsed_list.add(gson.fromJson(node.toString(), c));
}
return (parsed_list);
}
catch (Exception e)
{
return (new ArrayList<>());
}
}
//... other stuff
}
So, after we have all this (and the following stuff from the pre-mentioned SO question), what you said you were looking for is the callback in your working code, well that can be achieved in a couple of ways:
A straight forward way:
just call the method and override it's callback right there, e.g:
public class SomeClass
{
private List<User> mUsers;
private void someMethod()
{
// ... method does some stuff
NetworkManager.getInstance().getUsers(new SomeCustomListener<List<User>>()
{
#Override
public void getResult(List<User> all_users)
{
if (null != allUsers)
{
mUsers = allUsers;
// ... do other stuff with our info
}
}
});
// ... method does some more stuff
}
}
Or, in an indirect way (considering the time, memory consumption, etc. ), you can save the info you got in the same Singelton (or another container), and create a get method for it, and just get the object later (looks more slick)
remember: fire the request before (considering the latency for the response), as the nature of these callbacks is to be dependent on the response which might be delayed.
It would then look like this:
private List<User> mUsers;
private void someMethod()
{
// ... method does some stuff
mUsers = NetworkManager.getInstance().getUsersObject();
// ... method does some more stuff
}
A different option entirely would be to consider using Retrofit, that does the parsing for you, uses annotations, and is supposedly a lot faster , that might be what you're looking for (for the streamlined look) - I would read up on benchmarks, especially since the new 2.0 version came out.
Hope this Helps (although somewhat late)! :)

Android Parse JSON stuck on get task

I am trying to parse some JSON data. My code was working for awhile, and I am not sure what I changed to suddenly break the code. When I run my code I am not receiving any runtime errors or warnings. I create a new AsyncTask and execute this. When I call .get() on this new task, the debugger stalls on this line and takes more than 30 minutes. I have not been able to get the debugger or during run to complete this task.
JSON:
protected void setUp(Context context) {
_context = context;
getConfig();
}
// get config file
protected void getConfig() {
if (config != null)
return;
config = new Config();
String url = configURL;
AsyncTask<String, Integer, JSONObject> jsonTask = new DownloadJSONTask()
.execute(url);
JSONObject configItem = null;
try {
configItem = jsonTask.get(); //debugger pauses here
if (configItem == null)
return;
config.configVersion = configItem.getString("field_configversion");
config.currentAppVersion = configItem
.getString("field_currentappversion");
config.getSupportURL = configItem.getString("field_getsupporturl");
config.getCatalogURL = configItem.getString("field_getcatalogurl");
config.getDataVersion = configItem.getString("field_dataversion");
config.getDataUrl = configItem.getString("field_dataurl");
config.getDataApiKey = configItem.getString("field_dataapikey");
} catch (InterruptedException e) {
e.printStackTrace();
System.err.println("Download of config interrupted");
} catch (ExecutionException e) {
e.printStackTrace();
System.err.println("Download of config failed to execute");
} catch (JSONException e) {
e.printStackTrace();
}
cacheStaticData(_context);
}
DownloadJSONTask.java
package com.example.simplegraph;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;
import android.content.Context;
import android.os.AsyncTask;
public class DownloadJSONTask extends AsyncTask<String, Integer, JSONObject> {
private HttpClient client = new DefaultHttpClient();
private HttpGet request;
private HttpResponse response;
DownloadJSONTask() {
super();
}
// tries to grab the data for a JSONObject
#Override
protected JSONObject doInBackground(String... urls) {
request = new HttpGet(urls[0]);
try {
response = client.execute(request);
HttpEntity entity = response.getEntity();
if (entity != null) {
InputStream instream = entity.getContent();
String result = convertStreamToString(instream);
JSONObject json = new JSONObject(result);
instream.close();
return json;
}
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
// converts the InputStream to a string and add nl
private String convertStreamToString(InputStream is) {
BufferedReader br = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line = null;
try {
while ((line = br.readLine()) != null) {
sb.append(line + "\n");
}
} catch (IOException ioe) {
ioe.printStackTrace();
} finally {
try {
is.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
return sb.toString();
}
}
And HomeActivity.java
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
new AddStringTask().execute();
}
class AddStringTask extends AsyncTask<Void, String, Void> {
#Override
protected Void doInBackground(Void... unused) {
app = (EconApplication) getApplication();
getApp().setUp(HomeActivity.this);
HomeActivity.this.setUpDrawer();
return (null);
}
#Override
protected void onPostExecute(Void unused) {
setUpDataDisplay();
setUpGraphRange();
createTable();
createGraph(-1);
}
}
QUESTION: Why is my code getting stuck on .get()?

AsyncTask.get() blocks the caller thread. Use AsyncTask.execute() instead.
public final Result get ()
Added in API level 3
Waits if necessary for the computation to complete, and then retrieves
its result.
Returns The computed result.
Drawing from
How do I return a boolean from AsyncTask?
Try the below
new DownloadJSONTask(ActivityName.this).execute(url);
In your DownloadJSONTask
In the construcotr
TheInterface listener;
public DownloadJSONTask(Context context)
{
listener = (TheInterface) context;
}
Interface
public interface TheInterface {
public void theMethod(ArrayList<String> result); // your result type
}
In your doInbackground return the result. I am assuming its ArrayList of type String. Change the arraylist to what suits your requirement.
In your onPostExecute
if (listener != null)
{
listener.theMethod(result); // result is the ArrayList<String>
// result returned in doInbackground
// result of doInbackground computation is a parameter to onPostExecute
}
In your activity class implement the interface
public class ActivityName implements DownloadJSONTask.TheInterface
Then
#Override
public void theMethod(ArrayList<String> result) { // change the type of result according yo your requirement
// use the arraylist here
}
Edit: Alternative
You can makes your asynctask an inner class of your activity class. The result on doInbackground computation is a parameter to onPostExecute. Return result in doInbackground. Update ui in onPostExecute.

You can greatly simplify everything using the droidQuery library:
$.getJSON("http://www.example.com", null, new Function() {//this will run using an AsyncTask, get the JSON, and return either a JSONObject or JSONArray on the UI Thread.
#Overrde
public void invoke($ droidQuery, Object... params) {
if (params[0] instanceof JSONObject) { //it's often ok just to assume a JSONObject, making your first line simply: JSONObject obj = (JSONObject) params[0];
//JSONObject is returned
JSONObject json = (JSONObject) params[0];
//to easily parse this Object, convert it to a map first:
Map<String, ?> map = $.map(json);
//then you can just make a call like this:
if (map.contains("field_currentappversion")) {
config.currentAppVersion = (String) map.get("field_currentappversion");
}
}
else {
//JSONArray is returned
JSONArray json = (JSONArray) params[0];
//if you got an array, you can easily convert it to an Object[] for parsing:
Object[] array = $.makeArray(json);
}
}
});

How to wrap these classes into a AsyncClass and then using them?

I'm trying to put together a simple RSS reader, and found code on http://www.ibm.com/developerworks/opensource/library/x-android/
Todo so, I noticed that you can not do network operations from the main thread since Honeycomb and have a hard time wrapping this class into a working AsyncTask:
package tlib.net.rss;
import java.util.ArrayList;
import java.util.List;
import android.sax.Element;
import android.sax.EndElementListener;
import android.sax.EndTextElementListener;
import android.sax.RootElement;
import android.util.Xml;
public class SaxFeedParser extends BaseFeedParser {
public SaxFeedParser(String feedUrl) {
super(feedUrl);
}
public List<Message> parse() {
final Message currentMessage = new Message();
RootElement root = new RootElement("rss");
final List<Message> messages = new ArrayList<Message>();
Element channel = root.getChild("channel");
Element item = channel.getChild(ITEM);
item.setEndElementListener(new EndElementListener(){
public void end() {
messages.add(currentMessage.copy());
}
});
item.getChild(TITLE).setEndTextElementListener(new EndTextElementListener(){
public void end(String body) {
currentMessage.setTitle(body);
}
});
item.getChild(LINK).setEndTextElementListener(new EndTextElementListener(){
public void end(String body) {
currentMessage.setLink(body);
}
});
item.getChild(DESCRIPTION).setEndTextElementListener(new
EndTextElementListener(){
public void end(String body) {
currentMessage.setDescription(body);
}
});
item.getChild(PUB_DATE).setEndTextElementListener(new EndTextElementListener(){
public void end(String body) {
currentMessage.setDate(body);
}
});
try {
Xml.parse(this.getInputStream(), Xml.Encoding.UTF_8, root.getContentHandler());
} catch (Exception e) {
throw new RuntimeException(e);
}
return messages;
}
}
this code also calls the base-class: BaseFeedParser which i guess also has to be wrapped into a AsyncTask. the code for BaseFeedParser looks like:
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
public abstract class BaseFeedParser implements FeedParser {
// names of the XML tags
static final String CHANNEL = "channel";
static final String PUB_DATE = "pubDate";
static final String DESCRIPTION = "description";
static final String LINK = "link";
static final String TITLE = "title";
static final String ITEM = "item";
private final URL feedUrl;
protected BaseFeedParser(String feedUrl){
try {
this.feedUrl = new URL(feedUrl);
} catch (MalformedURLException e) {
throw new RuntimeException(e);
}
}
protected InputStream getInputStream() {
try {
return feedUrl.openConnection().getInputStream();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
I don't know if i'm simply dumb or having a bad day, but i don't get how this is supposted to happend. Could someone help me and my afternoon brain out to get this working?
Currently i use:
SaxFeedParser rss = new SaxFeedParser("http://www.androidster.com/android_news.rss");
messages = rss.parse();
for(Message message : messages)
{
tv.appendText(message);
}
to process the stream, how would i do if everything was done with AsyncTask?
Kind regards
Hiam

I have not tried this, but it should work.
Basically the AsyncTask will retrieve the url(s) contents, parse it and publish the parsed messages.The onProgressUpdate() is used to safely update the user interface as you please.
class ParserTask extends AsyncTask<String, List<Message>, Long> {
protected Long doInBackground(String... urls) {
if (urls == null || urls.length == 0)
return null;
for (String url : urls) {
SaxFeedParser rss = new SaxFeedParser(url);
List<Message> messages = rss.parse();
publishProgress(messages);
}
return null; //return somethingForPostExecute;
}
protected void onProgressUpdate(List<Message>... messages) {
if (messages == null || messages.length == 0)
return;
for (Message message : messages[0]) {
// tv.appendText(message);
// or call method from GUI thread (the activity)
}
}
protected void onPostExecute(Long nr) {
}
}
Then you use something like:
new ParserTask().execute("http://www.androidster.com/android_news.rss");
Or you could use multiple urls:
new ParserTask().execute(new String[]{"http://www.androidster.com/android_news.rss", "..."});