i have view pager defined in my app and i am trying to load images in view pager using volley library. I am doing as follows :
First, i am posting request to the server if response comes True, then i am sending another request in response method to fetch images from the server.
Here is the Error i am getting in log window:
java.lang.NullPointerException: Attempt to invoke virtual method 'com.android.volley.Request com.android.volley.RequestQueue.add(com.android.volley.Request)' on a null object reference
at tiffino.app.com.Home.loadDiscViewPager(Home.java:492)
at tiffino.app.com.Home$1.onResponse(Home.java:302)
at tiffino.app.com.Home$1.onResponse(Home.java:290)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)
at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6776)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1496)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1386)
Here is the code i am using:
OfferImageModel.java
public class OfferImageModel {
String Image;
public OfferImageModel(){
}
public OfferImageModel(String image) {
Image = image;
}
public String getImage() {
return Image;
}
public void setImage(String image) {
Image = image;
}
}
Home.java
public class Home extends Fragment{
String str1 = "Ajmer";
ViewPager discImages;
RequestQueue requestQueue, discQueue;
StringRequest stringRequest, discRequest;
private static final String URL = "https://tiffino.herokuapp.com/fetch";
private static final String OFFER_URL = "https://tiffino.herokuapp.com/offers";
List<OfferImageModel> offers;
DiscViewPager adapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_home, container, false);
discImages = view.findViewById(R.id.discImages);
offers = new ArrayList<>();
sendLocation(str1);
return view;
}
private void sendLocation(final String str1) {
requestQueue = Volley.newRequestQueue(getActivity());
stringRequest = new StringRequest(Request.Method.POST, URL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
if (response.equals("True")) {
loadDiscViewPager();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
HashMap<String, String> map = new HashMap<>();
map.put("name", str1);
return map;
}
};
requestQueue.add(stringRequest);
}
public void loadDiscViewPager() {
discRequest = new StringRequest(Request.Method.POST, OFFER_URL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONArray jsonArray = new JSONArray(response);
for (int i = 0; i < jsonArray.length(); i++) {
OfferImageModel model = new OfferImageModel();
JSONObject jsonObject = jsonArray.getJSONObject(i);
String loadImages = jsonObject.getString("Image");
model.setImage(loadImages);
offers.add(model);
}
adapter = new DiscViewPager(getActivity(), offers);
discImages.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener()
{
@Override
public void onErrorResponse(VolleyError error) {
}
})
{
@Override
protected Map<String, String> getParams() throws AuthFailureError {
HashMap<String, String> params = new HashMap<>();
params.put("Place",str1);
return params;
}
};
discQueue.add(discRequest);
}
}
DiscViewPager.java
public class DiscViewPager extends PagerAdapter {
private LayoutInflater layoutInflater;
Context context;
private List<OfferImageModel> offers;
public DiscViewPager(Context context, List<OfferImageModel> offers) {
this.context = context;
this.offers = offers;
}
@Override
public int getCount() {
return offers.size();
}
@Override
public boolean isViewFromObject(@NonNull View view, @NonNull Object o) {
return (view == o);
}
@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
assert layoutInflater != null;
View view = layoutInflater.inflate(R.layout.custom_offer, null);
ImageView offerImage = view.findViewById(R.id.offerImage);
OfferImageModel model = offers.get(position);
Picasso.with(context).load(model.getImage()).fit().centerInside().into(offerImage);
ViewPager vp = (ViewPager) container;
vp.addView(view, 0);
return view;
}
@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
ViewPager vp = (ViewPager) container;
View view = (View) object;
vp.removeView(view);
}
}
Please let me know what i am doing wrong in above code.
THANKS
