seon seon - 6 days ago 7
Android Question

Custom list inside Fragment not working

I have simply used a custom list inside a fragment.I have retrieved those data from api using volley.It shows following error.I am getting any idea to resolve this,Can somebody please help me.

java.lang.NullPointerException: Attempt to invoke virtual method 'com.android.volley.toolbox.ImageLoader com.example.user.ekta.AppController.getImageLoader()' on a null object reference
at com.example.user.ekta.MyBookAdapter.<init>(MyBookAdapter.java:25)
at com.example.user.ekta.FullInfoTabFragment.onCreateView(FullInfoTabFragment.java:85).


This is my Fragment class

package com.example.user.ekta;

import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v4.content.ContextCompat;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;

import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.VolleyLog;
import com.android.volley.toolbox.JsonArrayRequest;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;


public class FullInfoTabFragment extends Fragment {

private static final String EXTRA_SRORT_CARD_MODEL = "EXTRA_SRORT_CARD_MODEL";
// String transitionTag;
private SportCardModel sportCardModel;
private Toolbar toolbar;
private ImageView ivPhoto;

private static final String TAG = FullInfoTabFragment.class.getSimpleName();

private static final String url = "http://myeducationhunt.com/public/schools";

private ProgressDialog pDialog;
private List<MyBook> ourBooksListItems = new ArrayList<MyBook>();
private ListView listView;
private MyBookAdapter adapter;


public static FullInfoTabFragment newInstance(SportCardModel sportCardModel) {
FullInfoTabFragment fragment = new FullInfoTabFragment();
Bundle args = new Bundle();
args.putParcelable(EXTRA_SRORT_CARD_MODEL, sportCardModel);
fragment.setArguments(args);
return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
sportCardModel = getArguments().getParcelable(EXTRA_SRORT_CARD_MODEL);
}
if (savedInstanceState != null) {
sportCardModel = savedInstanceState.getParcelable(EXTRA_SRORT_CARD_MODEL);
}
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_full_info, container, false);
toolbar = (Toolbar) view.findViewById(R.id.toolbar);
ivPhoto = (ImageView) view.findViewById(R.id.ivPhoto);

listView = (ListView) view.findViewById(R.id.list);
adapter = new MyBookAdapter(getActivity(), ourBooksListItems);
listView.setAdapter(adapter);
listView.setTextFilterEnabled(true);

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

// OurSchool ourSchool = new OurSchool();
// Intent i = new Intent(getContext(), SchoolDetails.class);

// i.putExtra("id", ourSchoolsListItems.get(position).schoolId);
// i.putExtra("name", ourSchoolsListItems.get(position).schoolName);
// i.putExtra("location", ourSchoolsListItems.get(position).schoolLocation);
// i.putExtra("logo", ourSchoolsListItems.get(position).schoolLogo);
// i.putExtra("email", ourSchoolsListItems.get(position).schoolEmail);
// i.putExtra("website", ourSchoolsListItems.get(position).schoolWebsite);
// i.putExtra("created_at", ourSchoolsListItems.get(position).createdAt);
// i.putExtra("updated_at", ourSchoolsListItems.get(position).updatedAt);

// startActivity(i);

}
});
pDialog = new ProgressDialog(getActivity());
// Showing progress dialog before making http request
pDialog.setMessage("Loading…");
pDialog.show();

// Creating volley request obj
JsonArrayRequest schoolRequest = new JsonArrayRequest(url,
new Response.Listener<JSONArray>() {
@Override
public void onResponse(JSONArray response) {
Log.d(TAG, response.toString());
pDialog.hide();

// Parsing json
for (int i = 0; i < response.length(); i++) {
try {

JSONObject obj = response.getJSONObject(i);
MyBook myBook = new MyBook();

myBook.bookName = obj.getString("name");
myBook.bookAuthor = obj.getString("location");
myBook.bookCover= obj.getString("logo");
// adding schools to ourSchool list
ourBooksListItems.add(myBook);

} catch (JSONException e) {
e.printStackTrace();
}
}

adapter.notifyDataSetChanged();
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
VolleyLog.d(TAG, "Error: " + error.getMessage());
pDialog.hide();
}
});

// Adding request to request queue
AppController.getInstance().addToRequestQueue(schoolRequest);
return view;
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);

toolbar.setTitle(sportCardModel.getSportTitle());
toolbar.setNavigationIcon(R.drawable.ic_back);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
getActivity().onBackPressed();
}
});
toolbar.setBackgroundColor(ContextCompat.getColor(getContext(), sportCardModel.getBackgroundColorResId()));
ivPhoto.setImageResource(sportCardModel.getImageResId());
}

@Override
public void onSaveInstanceState(Bundle outState) {
outState.putParcelable(EXTRA_SRORT_CARD_MODEL, sportCardModel);
super.onSaveInstanceState(outState);
}

static class DividerItemDecoration extends RecyclerView.ItemDecoration {

private static final int[] ATTRS = new int[]{android.R.attr.listDivider};

private Drawable mDivider;

/**
* Default divider will be used
*/
public DividerItemDecoration(Context context) {
final TypedArray styledAttributes = context.obtainStyledAttributes(ATTRS);
mDivider = styledAttributes.getDrawable(0);
styledAttributes.recycle();
}

/**
* Custom divider will be used
*/
public DividerItemDecoration(Context context, int resId) {
mDivider = ContextCompat.getDrawable(context, resId);
}

@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
int left = parent.getPaddingLeft();
int right = parent.getWidth() - parent.getPaddingRight();

int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
View child = parent.getChildAt(i);

RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();

int top = child.getBottom() + params.bottomMargin;
int bottom = top + mDivider.getIntrinsicHeight();

mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
}
}


And this is my adapter class

package com.example.user.ekta;

import android.app.Activity;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;


import com.android.volley.toolbox.ImageLoader;
import com.android.volley.toolbox.NetworkImageView;

import java.util.List;

/**
* Created by user on 11/27/2016.
*/
public class MyBookAdapter extends BaseAdapter {

private Activity activity;
private LayoutInflater inflater;
private List<MyBook> ourbooksList;
ImageLoader imageLoader = AppController.getInstance().getImageLoader();

public MyBookAdapter(Activity activity, List<MyBook> ourbooksListsList) {
this.activity = activity;
this.ourbooksList = ourbooksListsList;
}


@Override
public int getCount() {
return ourbooksList.size();
}

@Override
public Object getItem(int location) {
return ourbooksList.get(location);
}

@Override
public long getItemId(int position) {
return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

if (inflater == null)
inflater = (LayoutInflater) activity
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null)
convertView = inflater.inflate(R.layout.list_books, null);

if (imageLoader == null)
imageLoader = AppController.getInstance().getImageLoader();
NetworkImageView bookCover = (NetworkImageView) convertView
.findViewById(R.id.bookCover);
TextView bookName = (TextView) convertView.findViewById(R.id.bookName);
TextView boookAuthor = (TextView) convertView.findViewById(R.id.bookAuthor);
MyBook m = ourbooksList.get(position);

bookCover.setImageUrl(m.getBookCover(), imageLoader);

bookName.setText("Name: " + m.getBookName());

boookAuthor.setText("Address: " + String.valueOf(m.getBookAuthor()));


return convertView;
}
}

Answer

AppController.getInstance() is returning null, you have not initialized your Appcontroller.

If AppController extends your application, then you have to change your manifest

android:name= "path to AppController" in app section.

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