One AsyncTask for multiple Fragments

Question

I'm Writing an application in Which i have different fragment. In all Fragment i have to use Async Task for fetching data from web server for that i have written a common Async class and implement an interface for getting result but there is casting error i don't know why? Error log is given below:

06-10 07:51:58.070    1459-1459/mewapp.interaconnect E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: mewapp.interaconnect, PID: 1459
java.lang.RuntimeException: Unable to start activity ComponentInfo{mewapp.interaconnect/mewapp.interaconnect.AsyncTask.Main2Activity}: java.lang.ClassCastException: mewapp.interaconnect.AsyncTask.Main2Activity cannot be cast to mewapp.interaconnect.AsyncTask.AsyncRequest$OnAsyncRequestComplete
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
        at android.app.ActivityThread.access$800(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.ClassCastException: mewapp.interaconnect.AsyncTask.Main2Activity cannot be cast to mewapp.interaconnect.AsyncTask.AsyncRequest$OnAsyncRequestComplete
        at mewapp.interaconnect.AsyncTask.AsyncRequest.<init>(AsyncRequest.java:21)
        at mewapp.interaconnect.AsyncTask.PostsActivity.onCreateView(PostsActivity.java:37)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
        at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:551)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
        at android.app.Activity.performStart(Activity.java:5241)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)
 at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
 at android.app.ActivityThread.access$800(ActivityThread.java:135)

This is my Error log

public class AsyncRequest extends AsyncTask<String, Integer, JSONObject> {

OnAsyncRequestComplete caller;
Context context;
JSONObject parameters;
ProgressDialog pDialog = null;

// Three Constructors
public AsyncRequest(Context a, JSONObject p) {
    caller = (OnAsyncRequestComplete) a;
    context = a;
    parameters = p;
}

// Interface to be implemented by calling activity
public  interface OnAsyncRequestComplete {
    public void asyncResponse(JSONObject response);
}

public JSONObject doInBackground(String... urls) {
    // get url pointing to entry point of API
    String address = urls[0].toString();
    Log.e("Test","InDoLoginProcess");
    return ReqSender.sendJson(parameters, address);
}

public void onPreExecute() {
    pDialog = new ProgressDialog(context);
    pDialog.setMessage("Loading data.."); // typically you will define such
    // strings in a remote file.
    pDialog.show();
}

public void onPostExecute(JSONObject response) {
    if (pDialog != null && pDialog.isShowing()) {
        pDialog.dismiss();
    }
    caller.asyncResponse(response);
}

protected void onCancelled(JSONObject response) {
    if (pDialog != null && pDialog.isShowing()) {
        pDialog.dismiss();
    }
    caller.asyncResponse(response);
}
}

This is my Asynctask Clss

public class PostsActivity extends Fragment implements
    AsyncRequest.OnAsyncRequestComplete {

TextView titlesView;
String apiURL = "MyServer";


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.activity_post, container, false);
    titlesView = (TextView) v.findViewById(R.id.post_titles);
    try {
        JSONObject obj = new JSONObject();
        obj.put(ICTags.REQUEST_TYPE_TAG,ICTags.LOGIN_TAG);
        obj.put(ICTags.USER_NAME_TAG, "raza4136");
        obj.put(ICTags.PASSWORD_TAG, "12345678");

        AsyncRequest getPosts = new AsyncRequest((Activity)getActivity(),obj);
        getPosts.execute(apiURL);
    }catch (JSONException e){
        e.printStackTrace();
    }
    return v;
}

@Override
public void asyncResponse(JSONObject objects)
{
        titlesView.setText(objects.toString());
}
}

This is my Fragment Class for calling Async

Answer 1

We cannot Cast Context object to Interface object. do the following :

1. change constructor in AsyncRequest class

   public AsyncRequest(Context a, JSONObject p,OnAsyncRequestComplete caller) { this.caller = caller; context = a; parameters = p; }

2. Replace following code in Your activity where you are calling AsyncRequest

   AsyncRequest getPosts = new AsyncRequest((Activity)getActivity(),obj,this);

I hope this will help you.