Develop Reference

create recycler view in fragment?

i want create a fragment and have inside a recycler view for show products ...
but when i render it is show this error : RecyclerView: No adapter attached; skipping layout
below i copy my codes;
this code is for adapter class :
private ArrayList<Products> ProductsList;
private Context context;
public Adapter(ArrayList<Products> productsList, Context context) {
ProductsList = productsList;
this.context = context;
}
#Override
public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(context).inflate(R.layout.row_layout, parent, false);
return new MyHolder(v);
}
#Override
public void onBindViewHolder(MyHolder holder, final int position) {
Products products = ProductsList.get(position);
holder.txtName.setText(products.getName());
holder.txtPrice.setText("$ " + products.getPrice());
Picasso.get().load(Config.ipValue + "/images/" + products.getPhoto()).into(holder.imgV);
holder.imgV.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
v.startAnimation(AnimationUtils.loadAnimation(context, android
.R.anim.slide_in_left));
}
});
}
#Override
public int getItemCount() {
return ProductsList.size();
}
class MyHolder extends RecyclerView.ViewHolder {
TextView txtName;
TextView txtPrice;
ImageView imgV;
public MyHolder(View itemView) {
super(itemView);
txtName = itemView.findViewById(R.id.rowTxtProductName);
txtPrice = itemView.findViewById(R.id.rowTxtPrice);
imgV = itemView.findViewById(R.id.rowImgProduct);
}
}
and this one for web api class :
public class WebApiHandler {
Context context;
String apiLink = "";
ArrayList<Products> products = new ArrayList<>();
public WebApiHandler(Context context) {
this.context = context;
}
void apiConnect(String type) {
switch (type) {
case "getproducts": {
apiLink = Config.getProductsWebApi;
break;
}
}
ProgressDialog dialog = ProgressDialog.show(context, "Connecting...",
"please wait", false, false);
StringRequest request = new StringRequest(Request.Method.POST,
apiLink, new Response.Listener<String>() {
#Override
public void onResponse(String response) {
dialog.dismiss();
showJson(response);
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
dialog.dismiss();
}
});
RequestQueue queue = Volley.newRequestQueue(context);
queue.add(request);
}
private void showJson(String response) {
products.clear();
try {
JSONObject jsonObject = new JSONObject(response);
JSONArray jsonArray = jsonObject.getJSONArray("response");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject object = jsonArray.getJSONObject(i);
String id = object.getString("id");
String name = object.getString("name");
String description = object.getString("description");
String price = object.getString("price");
String photo = object.getString("photo");
Products p = new Products(id, name, description, price, photo);
products.add(p);
}
} catch (JSONException e) {
e.printStackTrace();
}
VerticalFragment.productsArrayList = products;
IData iData = (IData) context;
iData.sendData();
}}
and my fragment code :
public class VerticalFragment extends Fragment implements IData {
RecyclerView rcVertical;
WebApiHandler webApiHandler;
static ArrayList<Products> productsArrayList = new ArrayList<>();
public VerticalFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_vertical, container, false);
rcVertical = view.findViewById(R.id.rcVertical);
webApiHandler = new WebApiHandler(getContext());
webApiHandler.apiConnect("getproducts");
rcVertical.addOnItemTouchListener(new RecyclerTouchListener(getContext(), rcVertical,
new RecyclerTouchListener.ClickListener() {
#Override
public void onClick(View view, int position) {
ProductActivity.products = productsArrayList.get(position);
startActivity(new Intent(getContext(), ProductActivity.class));
}
#Override
public void onLongClick(View view, int position) {
}
}));
return view;
}
#Override
public void sendData() {
Adapter adapter = new Adapter(productsArrayList, getContext());
rcVertical.setLayoutManager(new LinearLayoutManager((getContext())));
rcVertical.setItemAnimator(new DefaultItemAnimator());
rcVertical.setAdapter(adapter);
}}
i should say i create a interface and have one method i say it sendData

This is a common error when there is no adapter attached to recyclerview upon showing recyclerview. It will not cause any harm to your app, but you could avoid it by setting empty adapter without data, and later when you get your data, provide it to your adapter and notify it
Edit - Example added
Create setter for your list in adapter. After that, in your fragment make adapter global and in onCreateView make instance of your adapter and attach it to recyclerview
adapter = new Adapter(new ArrayList<>(), getContext());
rcVertical.setAdapter(adapter);
...Initialize recyclerview...
And then in your sendData interface put your loaded values in it
adapter.setData(productsArrayList);
adapter.notifyDataSetChanged();

Cannot cast onItem clicklistener inside Fragment Class form Adapter Class

I have an Fragment with recycleview where I populate it with json items from internet.
It load fine and Next step I want to is open new Activity when any row is clicked. It works in activity, thus I modified the same code for fragment but for fragment it throws exception in line
mExampleAdapter.setOnItemClickListener(getActivity());
with errror setOnItemClickListener of refrence adatper cannot be applied to Fragment activty and thus when I change line to
(ExampleAdapter.OnItemClickListener)
and when i build and run . Then app crashes with error that Mainactivity which holds framgnet cannot be cast in to .ExampleAdapter$OnItemClickListener
Here is my whole Fragment class
public class Mynotes extends Fragment implements ExampleAdapter.OnItemClickListener{
public static final String YTD_LINK = "link";
private RecyclerView mRecyclerView;
private ExampleAdapter mExampleAdapter;
private ArrayList<ExampleItem> mExampleList;
private RequestQueue mRequestQueue;
String url="https://api.myjson.com/bins/16mecx";
public Mynotes() {
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.activity_jsonfeed, container, false);
mRecyclerView = view.findViewById(R.id.recycler_view);
mRecyclerView.setHasFixedSize(true);
mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
mRecyclerView.addItemDecoration(new MyDividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL, 36));
mExampleList = new ArrayList<>();
mExampleAdapter = new ExampleAdapter(getActivity(), mExampleList);
mRecyclerView.setAdapter(mExampleAdapter);
mExampleAdapter.setOnItemClickListener((ExampleAdapter.OnItemClickListener) getActivity());
parseJSON();
return view;
}
private void parseJSON() {
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
myProgressBar.setVisibility(View.GONE);
try {
JSONArray jsonArray = response.getJSONArray("hits");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject hit = jsonArray.getJSONObject(i);
String videoTitle = hit.getString("title");
String link = hit.getString("link");
mExampleList.add(new ExampleItem(videoTitle, link));
mExampleAdapter.notifyDataSetChanged();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
mRequestQueue.add(request);
}
#Override
public void onItemClick(int position) {
Intent intent = new Intent(getActivity(), NewActiviyt.class);
ExampleItem clickedItem = mExampleList.get(position);
intent.putExtra(YTD_LINK, clickedItem.getmLink());
startActivity(intent);
}
#Override
public void onRefresh() {
}
}
and my Adapter Class is
public class ExampleAdapter extends RecyclerView.Adapter<ExampleAdapter.ExampleViewHolder> {
private Context mContext;
private ArrayList<ExampleItem> mExampleList;
private OnItemClickListener mListener;
public interface OnItemClickListener {
void onItemClick(int position);
}
public void setOnItemClickListener(OnItemClickListener listener) {
mListener = listener;
}
public ExampleAdapter(Context context, ArrayList<ExampleItem> exampleList) {
mContext = context;
mExampleList = exampleList;
}
#Override
public ExampleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(mContext).inflate(R.layout.example_item, parent, false);
return new ExampleViewHolder(v);
}
#Override
public void onBindViewHolder(ExampleViewHolder holder, int position) {
ExampleItem currentItem = mExampleList.get(position);
String title = currentItem.getTitle();
// int likeCount = currentItem.getLikeCount();
// String imageUrl = currentItem.getImageUrl();
holder.mTextViewCreator.setText(title);
// holder.mTextViewLikes.setText("Likes: " + likeCount);
// Glide.with(mContext).load(imageUrl).apply(RequestOptions.circleCropTransform()).into(holder.mImageView);
}
#Override
public int getItemCount() {
return mExampleList.size();
}
public class ExampleViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
public TextView mTextViewCreator;
// public TextView mTextViewLikes;
// public ImageView mImageView;
public ExampleViewHolder(View itemView) {
super(itemView);
// mTextViewLikes = itemView.findViewById(R.id.text_view_likes);
// mImageView = itemView.findViewById(R.id.image_view);
mTextViewCreator = itemView.findViewById(R.id.text_title);
}
#Override
public void onClick(View view) {
if (mListener != null) {
int position = getAdapterPosition();
if (position != RecyclerView.NO_POSITION) {
mListener.onItemClick(position);
}
}
}
}
}
Thanks in advance.

replace getActivity with getContext when you work in fragment,
You can read more here
What is different between getContext and getActivity from Fragment in support library?

Your activity should implement ExampleAdapter.OnItemClickListener

New fetch data is not show on recycler list when pull down to refresh

I want to implement one code where data will come on Scroll and if the data is add on list then we pull down(SwipeRefreshLayout) the new data will come on that list. In my below code the add on data is coming in response but not come in list? I have read many tutorials like this but data is coming on Swipe refresh but not shown on list. Thank you in advance
public class UpdatesFragment extends Fragment implements SwipeRefreshLayout.OnRefreshListener{
SwipeRefreshLayout mSwipeRefreshLayout;
UserSessionManager session;
private List<SuperHero> listSuperHeroes;
private RecyclerView recyclerView;
private RecyclerView.LayoutManager layoutManager;
private RecyclerView.Adapter adapter;
public ProgressBar progressBar;
public String user_id;
TextView textView;
FloatingActionButton fab;
public int a=1;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view= inflater.inflate(R.layout.fragment_updates, container, false);
session = new UserSessionManager(getActivity());
// get user data from session
HashMap<String, String> user = session.getUserDetails();
user_id = user.get(UserSessionManager.KEY_USER_ID);
// SwipeRefreshLayout
mSwipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipe_container);
mSwipeRefreshLayout.setOnRefreshListener(this);
mSwipeRefreshLayout.setColorSchemeResources(R.color.colorPrimary,
android.R.color.holo_green_dark,
android.R.color.holo_orange_dark,
android.R.color.holo_blue_dark);
/**
* Showing Swipe Refresh animation on activity create
* As animation won't start on onCreate, post runnable is used
*/
mSwipeRefreshLayout.post(new Runnable() {
#Override
public void run() {
mSwipeRefreshLayout.setRefreshing(true);
// Fetching data from server
getDataFromServer(1);
}
});
return view;
}
public void onViewCreated(View v, Bundle savedInstanceState) {
super.onViewCreated(v, savedInstanceState);
fab = (FloatingActionButton)v.findViewById(R.id.fab);
recyclerView = (RecyclerView) v.findViewById(R.id.updatesRecycler);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(layoutManager);
listSuperHeroes = new ArrayList<>();
adapter = new CardAdapter(listSuperHeroes, getActivity());
recyclerView.setAdapter(adapter);
textView = (TextView)v.findViewById(R.id.text);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i = new Intent(getContext(), AddWebPostActivity.class);
startActivity(i);
}
});
getDataFromServer(a);
recyclerView.setOnScrollListener(new EndlessRecyclerOnScrollListener((LinearLayoutManager) layoutManager) {
#Override
public void onLoadMore(int current_page) {
getDataFromServer(current_page);
}
});
}
public void getDataFromServer(int requestCount) {
Log.e("count",String.valueOf(requestCount));
final String DATA_URL = "https://XYZ.php?username="+user_id + "&page="+requestCount;
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(DATA_URL,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
mSwipeRefreshLayout.setRefreshing(false);
Log.e("URL___________",DATA_URL);
Log.e("response___________", String.valueOf(response));
parseData(response);
adapter.notifyDataSetChanged();
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getContext(), "No More Items Available", Toast.LENGTH_SHORT).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(getContext());
requestQueue.getCache().clear();
requestQueue.add(jsonArrayRequest);
}
private void parseData(JSONArray array) {
for (int i = 0; i < array.length(); i++) {
SuperHero superHero = new SuperHero();
JSONObject json = null;
try {
json = array.getJSONObject(i);
superHero.setPost_title(json.getString(Config.TAG_POST_TITLE));
superHero.setPost_content(json.getString(Config.TAG_POST_CONTENT));
superHero.setPost_parent(json.getString(Config.TAG_POST_PARENT));
superHero.setPost_date(json.getString(Config.TAG_POST_DATE));
superHero.setPost_date_gmt(json.getString(Config.TAG_POST_DATE_GMT));
superHero.setScheduled_date(json.getString(Config.TAG_SCHEDULED_DATE));
superHero.setTo_ping(json.getString(Config.TAG_IP_ADDRESS));
superHero.setVisit_post(json.getString(Config.TAG_VISIT_POST));
superHero.setUr_id(json.getString(Config.TAG_UR_ID));
} catch (JSONException e) {
e.printStackTrace();
}
listSuperHeroes.add(superHero);
}
}
/**
* Called when a swipe gesture triggers a refresh.
*/
#Override
public void onRefresh() {
getDataFromServer(1);
}
}
Adapter
public class CardAdapter extends RecyclerView.Adapter<CardAdapter.ViewHolder> {
UserSessionManager session;
public String user_id;
public String ur_id;
private Context context;
//String visit;
//List to store all superheroes
List<SuperHero> superHeroes;
//Constructor of this class
public CardAdapter(List<SuperHero> superHeroes, Context context){
super();
//Getting all superheroes
this.superHeroes = superHeroes;
this.context = context;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext())
.inflate(R.layout.web_post, parent, false);
// Session class instance
session = new UserSessionManager(context);
session.checkLogin();
// get user data from session
HashMap<String, String> user = session.getUserDetails();
user_id = user.get(UserSessionManager.KEY_USER_ID);
ViewHolder viewHolder = new ViewHolder(v);
return viewHolder;
}
#Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
//Getting the particular item from the list
final SuperHero superHero = superHeroes.get(position);
holder.tvPostTitle.setText(superHero.getPost_title());
holder.tvPostContent.setText(superHero.getPost_content());
holder.tvPostDateTime1.setText(superHero.getPost_date() +" / " +superHero.getPost_date_gmt());
final String visit = superHero.getVisit_post();
holder.tvVisitPost.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent i = new Intent(context,VisitWebView.class);
i.putExtra("visitURL",visit);
context.startActivity(i);
}
});
}
#Override
public int getItemCount() {
return superHeroes.size();
}
#Override
public int getItemViewType(int position) {
return position;
}
class ViewHolder extends RecyclerView.ViewHolder{
//Views
public TextView tvPostTitle,tvPostContent,tvPostDateTime1,tvVisitPost;
public ImageButton removeButton;
//Initializing Views
public ViewHolder(final View itemView) {
super(itemView);
tvPostTitle = (TextView) itemView.findViewById(R.id.tvPostTitle);
tvPostContent = (TextView) itemView.findViewById(R.id.tvPostContent);
tvPostDateTime1 = (TextView) itemView.findViewById(R.id.tvPostDateTime1);
tvVisitPost = (TextView) itemView.findViewById(R.id.tvVisitPost);
removeButton = (ImageButton) itemView.findViewById(R.id.removeButton);
}
}
}

use this method
mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
mSwipeRefreshLayout.setRefreshing(true);
getDataFromServer(1);
}
instead of this
mSwipeRefreshLayout.post(new Runnable() {
#Override
public void run() {
mSwipeRefreshLayout.setRefreshing(true);
// Fetching data from server
getDataFromServer(1);
}
});

Please call adapter and pass fresh list data after this line
listSuperHeroes.add(superHero) in parseData(response) function ;
adapter = new CardAdapter(listSuperHeroes, getActivity());
recyclerView.setAdapter(adapter)
adapter.notifyDataSetChanged();

MySQL data is not being displayed in Android RecyclerView (Logcat error: Couldn't load memtrack module)

I have just started developing Android application. I have used XAMPP to generate the database(MYSQL) and php to convert the extracted data into JSON. However, I could not display the following JSON output in Android Recyclerview and there is no error being generated while building this application. I have also referred to some other examples/solutions from this website but I still could not solve this issue. The code I have used is below. May I know which part can be corrected or missing?
herblist.php (to convert MYSQL data to JSON)
<?php
include 'dbConnect.php';
// Create connection
$conn = new mysqli($HostName, $HostUser, $HostPass, $DatabaseName);
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
mysqli_set_charset($conn, 'utf8');
$sql = "SELECT * FROM herb";
$result = $conn->query($sql);
if ($result->num_rows >0) {
while($row[] = $result->fetch_assoc()) {
$tem = $row;
$json = json_encode($tem);
}
} else {
echo "No Results Found.";
}
echo $json;
$conn->close();
?>
JSON generated by herblist.php
[{"h_name":"Basil","h_image":"http:\/\/localhost\/Herb\/Herb_image\/basil.jpg"},{"h_name":"Cilantro","h_image":"http:\/\/localhost\/Herb\/Herb_image\/cilantro.jpg"},{"h_name":"Kaffir lime leaf","h_image":"http:\/\/localhost\/Herb\/Herb_image\/kaffir_lime.jpg"},{"h_name":"Lemongrass","h_image":"http:\/\/localhost\/Herb\/Herb_image\/lemongrass.jpg"},{"h_name":"Mint","h_image":"http:\/\/localhost\/Herb\/Herb_image\/mint.jpg"},{"h_name":"Oregano","h_image":"http:\/\/localhost\/Herb\/Herb_image\/oregano.jpg"},{"h_name":"Pandan leaf","h_image":"http:\/\/localhost\/Herb\/Herb_image\/pandan.jpg"},{"h_name":"Parsley","h_image":"http:\/\/localhost\/Herb\/Herb_image\/parsley.jpg"},{"h_name":"Rosemary","h_image":"http:\/\/localhost\/Herb\/Herb_image\/rosemary.jpg"},{"h_name":"Thyme","h_image":"http:\/\/localhost\/Herb\/Herb_image\/thyme.jpg"}]
searchActivity.java (the main activity)
public class searchActivity extends AppCompatActivity {
List<DataAdapter> ListDataAdapter;
RecyclerView recyclerView;
String HTTP_JSON_URL = "http://localhost/Herb/herblist.php";
String Image_Name_JSON = "h_name";
String Image_URL_JSON = "h_image";
JsonArrayRequest RequestOfJSonArray ;
RequestQueue requestQueue ;
View view ;
int RecyclerViewItemPosition ;
RecyclerView.LayoutManager RecyclerViewLayoutManager;
RecyclerView.Adapter recyclerViewadapter;
ArrayList<String> ImageTitleNameArrayListForClick;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_search);
ImageTitleNameArrayListForClick = new ArrayList<>();
ListDataAdapter = new ArrayList<>();
recyclerView = (RecyclerView) findViewById(R.id.recyclerview1);
recyclerView.setHasFixedSize(true);
RecyclerViewLayoutManager = new LinearLayoutManager(this);
recyclerView.setAdapter(recyclerViewadapter);
recyclerView.setLayoutManager(RecyclerViewLayoutManager);
JSON_HTTP_CALL();
// Implementing Click Listener on RecyclerView.
recyclerView.addOnItemTouchListener(new RecyclerView.OnItemTouchListener() {
GestureDetector gestureDetector = new GestureDetector(searchActivity.this, new GestureDetector.SimpleOnGestureListener() {
#Override public boolean onSingleTapUp(MotionEvent motionEvent) {
return true;
}
});
#Override
public boolean onInterceptTouchEvent(RecyclerView Recyclerview, MotionEvent motionEvent) {
view = Recyclerview.findChildViewUnder(motionEvent.getX(), motionEvent.getY());
if(view != null && gestureDetector.onTouchEvent(motionEvent)) {
//Getting RecyclerView Clicked Item value.
RecyclerViewItemPosition = Recyclerview.getChildAdapterPosition(view);
// Showing RecyclerView Clicked Item value using Toast.
Toast.makeText(searchActivity.this, ImageTitleNameArrayListForClick.get(RecyclerViewItemPosition), Toast.LENGTH_LONG).show();
}
return false;
}
#Override
public void onTouchEvent(RecyclerView Recyclerview, MotionEvent motionEvent) {
}
#Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
}
});
}
public void JSON_HTTP_CALL(){
RequestOfJSonArray = new JsonArrayRequest(HTTP_JSON_URL,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
ParseJSonResponse(response);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
requestQueue = Volley.newRequestQueue(searchActivity.this);
requestQueue.add(RequestOfJSonArray);
}
public void ParseJSonResponse(JSONArray array){
for(int i = 0; i<array.length(); i++) {
DataAdapter GetDataAdapter2 = new DataAdapter();
JSONObject json = null;
try {
json = array.getJSONObject(i);
GetDataAdapter2.setImageTitle(json.getString(Image_Name_JSON));
// Adding image title name in array to display on RecyclerView click event.
ImageTitleNameArrayListForClick.add(json.getString(Image_Name_JSON));
GetDataAdapter2.setImageUrl(json.getString(Image_URL_JSON));
} catch (JSONException e) {
e.printStackTrace();
}
ListDataAdapter.add(GetDataAdapter2);
}
recyclerViewadapter = new RecyclerViewAdapter(ListDataAdapter, this);
recyclerView.setAdapter(recyclerViewadapter);
}
}
DataAdapter.java (The adapter part of the text in cardview)
public class DataAdapter{
public String ImageURL;
public String ImageTitle;
public String getImageUrl() {return ImageURL;}
public void setImageUrl(String ImageServerUrl) {this.ImageURL = ImageServerUrl;}
public String getImageTitle() {return ImageTitle;}
public void setImageTitle(String ImageTitleName) {this.ImageTitle = ImageTitleName;}
}
ImageAdapter.java (The adapter part of the image in cardview)
public class ImageAdapter {
public static ImageAdapter imageAdapter;
public Network networkOBJ ;
public RequestQueue requestQueue1;
public ImageLoader Imageloader1;
public Cache cache1 ;
public static Context context1;
LruCache<String, Bitmap> LRUCACHE = new LruCache<String, Bitmap>(30);
private ImageAdapter(Context context) {
this.context1 = context;
this.requestQueue1 = RequestQueueFunction();
Imageloader1 = new ImageLoader(requestQueue1, new ImageLoader.ImageCache() {
#Override
public Bitmap getBitmap(String URL) {
return LRUCACHE.get(URL);
}
#Override
public void putBitmap(String url, Bitmap bitmap) {
LRUCACHE.put(url, bitmap);
}
});
}
public ImageLoader getImageLoader() {
return Imageloader1;
}
public static ImageAdapter getInstance(Context SynchronizedContext) {
if (imageAdapter == null) {
imageAdapter = new ImageAdapter(SynchronizedContext);
}
return imageAdapter;
}
public RequestQueue RequestQueueFunction() {
if (requestQueue1 == null) {
cache1 = new DiskBasedCache(context1.getCacheDir());
networkOBJ = new BasicNetwork(new HurlStack());
requestQueue1 = new RequestQueue(cache1, networkOBJ);
requestQueue1.start();
}
return requestQueue1;
}
}
RecyclerViewAdapter.java
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
Context context;
List<DataAdapter> dataAdapters;
ImageLoader imageLoader;
public RecyclerViewAdapter(List<DataAdapter> getDataAdapter, Context context){
super();
this.dataAdapters = getDataAdapter;
this.context = context;
}
#Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cardview, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
#Override
public void onBindViewHolder(ViewHolder Viewholder, int position) {
DataAdapter dataAdapterOBJ = dataAdapters.get(position);
imageLoader = ImageAdapter.getInstance(context).getImageLoader();
imageLoader.get(dataAdapterOBJ.getImageUrl(),
ImageLoader.getImageListener(
Viewholder.VollyImageView,//Server Image
R.mipmap.ic_launcher,//Before loading server image the default showing image.
android.R.drawable.ic_dialog_alert //Error image if requested image dose not found on server.
)
);
Viewholder.VollyImageView.setImageUrl(dataAdapterOBJ.getImageUrl(), imageLoader);
Viewholder.ImageTitleTextView.setText(dataAdapterOBJ.getImageTitle());
}
#Override
public int getItemCount() {
return dataAdapters.size();
}
class ViewHolder extends RecyclerView.ViewHolder{
public TextView ImageTitleTextView;
public NetworkImageView VollyImageView ;
public ViewHolder(View itemView) {
super(itemView);
ImageTitleTextView = (TextView) itemView.findViewById(R.id.ImageNameTextView) ;
VollyImageView = (NetworkImageView) itemView.findViewById(R.id.VolleyImageView) ;
}
}
}
activity_search.xml (xml file of the main activity)
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v7.widget.RecyclerView
android:id="#+id/recyclerview1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</RelativeLayout>
cardview.xml
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/cardview1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardElevation="5dp"
card_view:contentPadding="5dp"
card_view:cardCornerRadius="5dp"
card_view:cardMaxElevation="5dp"
>
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#ECEFF1">
<com.android.volley.toolbox.NetworkImageView
android:id="#+id/VolleyImageView"
android:layout_width="150dp"
android:layout_height="100dp"
android:src="#mipmap/ic_launcher"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toEndOf="#+id/VolleyImageView"
android:textSize="20sp"
android:textColor="#000"
android:text="JSon Image Name"
android:id="#+id/ImageNameTextView"
android:layout_centerVertical="true"/>
</RelativeLayout>
</android.support.v7.widget.CardView>

First change this
recyclerView.setHasFixedSize(true);
RecyclerViewLayoutManager = new LinearLayoutManager(this);
recyclerView.setAdapter(recyclerViewadapter);
recyclerView.setLayoutManager(RecyclerViewLayoutManager);
To
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerViewadapter = new RecyclerViewAdapter(ListDataAdapter, this);
recyclerView.setAdapter(recyclerViewadapter);
Second remove this two line from JSON_HTTP_CALL() method
recyclerViewadapter = new RecyclerViewAdapter(ListDataAdapter, this);
recyclerView.setAdapter(recyclerViewadapter);
and put this line
recyclerViewadapter.notifyDataSetChanged();

How to detect if RecyclerView is empty?

I have a RecyclerView getting external JSON data parsed from a server. It works fine however the Volley async task on JSON sometimes takes a while and when it does the fragment displays an empty blank view.
How can I create a test to check if the view is empty and display a msg if it is? I tried to check:
if (recyclerView == null)
if (jsonList == null)
if (adapter.getItemCount() == 0)
if (bundle == null)
But those tests either dont do anything or they display the error message every single time even if the RecyclerView is not empty.
This is the code on the fragment:
public void onViewCreated(View view, Bundle savedInstanceState) {
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
layoutManager.supportsPredictiveItemAnimations();
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setClickable(true);
recyclerView.setHasFixedSize(true);
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL_LIST));
NovaAdapter novaAdapter = new NovaAdapter(getActivity(),jsonList);
if (novaAdapter.getItemCount() != 0) {
recyclerView.setAdapter(novaAdapter);
}else{
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Retrieving data from Server");
pDialog.show();
}
super.onViewCreated(view, savedInstanceState);
and the method on the Adapter:
#Override
public int getItemCount() {
return (null != novaList ? novaList.size() : 0);
}
The way it is now the progress dialog always run no matter if the view is empty or not.
UPDATE: Here's the adapter code:
public class NovaAdapter extends RecyclerView.Adapter<NovaListRowHolder> {
ArrayList<HashMap<String, String>> novaList = new ArrayList<HashMap<String, String>>();
public static final String STATUS = "status";
public static final String NAME = "name";
public static final String ID = "id";
private Context mContext;
public NovaAdapter(Context context, ArrayList<HashMap<String, String>> novaList) {
this.novaList = novaList;
this.mContext = context;
}
#Override
public NovaListRowHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.instances_list, null);
NovaListRowHolder mh = new NovaListRowHolder(v);
return mh;
}
#Override
public void onBindViewHolder(NovaListRowHolder novaListRowHolder, int i) {
HashMap<String, String> e = novaList.get(i);
novaListRowHolder.name.setText(e.get(NAME));
novaListRowHolder.status.setText(e.get(STATUS));
novaListRowHolder.setId(e.get(ID));
}
#Override
public int getItemCount() {
return (null != novaList ? novaList.size() : 0);
}class NovaListRowHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
protected TextView name;
protected TextView status;
protected String id;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public NovaListRowHolder(View view) {
super(view);
view.setOnClickListener(this);
this.name = (TextView) view.findViewById(R.id.nameInstance);
this.status = (TextView) view.findViewById(R.id.statusInstance);
}
public void onClick(View view){
Dialog dialog = new Dialog(view.getContext());
dialog.setContentView(R.layout.instances_listdetail);
dialog.setTitle("Details " + name.getText() + " " + getPosition());
dialog.show();
}
UPDATE2:
I updated another class which is pretty much the same as the one above with a callback interface however now the recyclerView displays for 1 second and then goes blank. The dialog doesn't even show. Here's the code:
public class SubnetsFragment extends Fragment implements OnJSONLoaded{
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
private OnFragmentInteractionListener mListener;
public ArrayList<HashMap<String, String>> jsonList;
public RecyclerView recyclerView;
public ProgressDialog pDialog;
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static SubnetsFragment newInstance(int sectionNumber) {
SubnetsFragment fragment = new SubnetsFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public SubnetsFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
Bundle extras = getArguments();
Serializable parsedList = extras.getSerializable("SubnetsParsed");
jsonList = (ArrayList<HashMap<String, String>>)parsedList;
if (extras == null){
AlertDialog.Builder alert = new AlertDialog.Builder(getActivity());
alert.setTitle("Token Expired");
alert.setMessage("Authentication Token expired! Please login again.")
.setNeutralButton("Connect", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialogInterface, int i) {
Intent intent = new Intent(getActivity(), Login.class);
startActivity(intent);
getActivity().finish();
getFragmentManager().beginTransaction().remove(SubnetsFragment.this).commit();
}
});
AlertDialog alertDialog = alert.create();
alertDialog.show();
}
View rootView = inflater.inflate(R.layout.fragment_subnets, container, false);
recyclerView = (RecyclerView)rootView.findViewById(R.id.subnetsRV);
return rootView;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
layoutManager.supportsPredictiveItemAnimations();
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setClickable(true);
recyclerView.setHasFixedSize(true);
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL_LIST));
onJsonLoaded(jsonList);
}
#Override
public void onJsonLoaded(ArrayList<HashMap<String, String>> list) {
SubnetsParser.setOnJSONLoadedListener(new OnJSONLoaded() {
#Override
public void onJsonLoaded(ArrayList<HashMap<String, String>> list) {
if (list.size() != 0){
SubnetsAdapter subnetsAdapter = new SubnetsAdapter(getActivity(),jsonList);
recyclerView.setAdapter(subnetsAdapter);
}else {
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Retrieving data from Server");
pDialog.show();
}
}
});
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
((Stackerz) activity).onSectionAttached(
getArguments().getInt(ARG_SECTION_NUMBER));
//try {
// mListener = (OnFragmentInteractionListener) activity;
//} catch (ClassCastException e) {
// throw new ClassCastException(activity.toString()
// + " must implement OnFragmentInteractionListener");
//}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onFragmentInteraction(Uri uri);
}
}
And this is the JSON Parser class:
public class SubnetsParser extends Activity{
public static final String NAME = "name";
public static final String GW = "gw";
public static final String CIDR = "cidr";
public static final String ID = "id";
public String authToken;
public String neutronURL;
public static SubnetsParser parser = null;
public static OnJSONLoaded mListener;
public static void setOnJSONLoadedListener(OnJSONLoaded listener) {
mListener = listener;
}
public interface OnJSONLoaded {
void onJsonLoaded(ArrayList<HashMap<String, String>> list);
}
public static SubnetsParser shared(){
if (parser == null){
parser = new SubnetsParser();
}
return parser ;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
public static ArrayList<HashMap<String, String>> parseJSON(String subnetsJSON){
ArrayList<HashMap<String, String>> jsonList = new ArrayList<HashMap<String, String>>();
try {
Subnets subnets = new Subnets();
JSONObject subnet = new JSONObject(subnetsJSON);
JSONArray subnetobj = subnet.getJSONArray("subnets");
for (int i = 0; i < subnetobj.length(); i++) {
JSONObject objsrv = subnetobj.getJSONObject(i);
subnets.setName(objsrv.getString("name"));
subnets.setGw(objsrv.getString("gateway_ip"));
subnets.setCidr(objsrv.getString("cidr"));
subnets.setId(objsrv.getString("id"));
HashMap<String, String> map = new HashMap<String, String>();
map.put(NAME, subnets.getName());
map.put(GW, subnets.getGw());
map.put(CIDR, subnets.getCidr());
map.put(ID, subnets.getId());
jsonList.add(map);
}
} catch (JSONException e) {
Log.d("ErrorInitJSON", e.toString());
e.printStackTrace();
}
Collections.sort(jsonList, new Comparator<HashMap<String, String>>() {
#Override
public int compare(HashMap<String, String> lhs, HashMap<String, String> rhs) {
return (lhs.get("name")).compareToIgnoreCase(rhs.get("name"));
}
});
if (mListener != null) {
mListener.onJsonLoaded(jsonList);
}
return jsonList;
}
}

You can check if it's empty by running:
if (adapter.getItemCount() == 0)
If it's not working it means you haven't Override the getItemCount on your adapter! so make sure it's overrided:
#Override
public int getItemCount() {
return mDataSet.size(); // Where mDataSet is the list of your items
}
Update:
So based on your update this is how you could proceed. In my opinion you just need a callback. You are checking if the list is empty on your onViewCreated. You should, instead, use a callback. Do something like that:
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
layoutManager.supportsPredictiveItemAnimations();
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setClickable(true);
recyclerView.setHasFixedSize(true);
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL_LIST));
pDialog = new ProgressDialog(getActivity());
pDialog.setMessage("Retrieving data from Server");
pDialog.show();
}
In the class you are using to populate your jsonList, I assume an asynctask or a separate class add this:
private OnJsonLoaded mListener;
public void setOnJsonLoadedListener(OnJsonLoaded listener) {
mListener = listener;
}
public interface OnJsonLoaded {
void onJsonLoaded(ArrayList<HashMap<String, String>> list);
}
now, in the asynctask that populate ur jsonLise or when the json parser finish his job, call the listener:
if (mListener != null) {
mListener.onJsonLoaded(jsonList);
}
In your fragment (the one with NovaAdapter novaAdapter = new NovaAdapter(getActivity(),jsonList); and your recyclerview) add the interface implementation:
classThatParseJson.setOnJsonLoadedListener(new OnJsonLoaded() {
#Override
public void onJsonLoaded(ArrayList<HashMap<String, String>> list) {
if (list.size() != 0) {
NovaAdapter novaAdapter = new NovaAdapter(getActivity(),jsonList);
recyclerView.setAdapter(novaAdapter);
} else {
// Show something like a dialog that the json list is 0 or do whatever you want... here the jsonlist have a count of 0 so it's empty!
}
}
});
the code may containts errors, i written it by hand without using IDE so maybe you have to fix small things but the logic is quite clear!
Update based on your Update 2:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_subnets, container, false);
recyclerView = (RecyclerView)rootView.findViewById(R.id.subnetsRV);
return rootView;
}
#Override
public void onViewCreated(View view, Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
LinearLayoutManager layoutManager = new LinearLayoutManager(getActivity());
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
layoutManager.supportsPredictiveItemAnimations();
recyclerView.setLayoutManager(layoutManager);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setClickable(true);
recyclerView.setHasFixedSize(true);
recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), DividerItemDecoration.VERTICAL_LIST));
// start json parser here instead of passing to fragment as a bundle
SubnetsParser.parseJSON(yourparams);
}
#Override
public void onJsonLoaded(ArrayList<HashMap<String, String>> list) {
SubnetsParser.setOnJSONLoadedListener(new OnJSONLoaded() {
#Override
public void onJsonLoaded(ArrayList<HashMap<String, String>> list) {
if (list.size() != 0){
SubnetsAdapter subnetsAdapter = new SubnetsAdapter(getActivity(),jsonList);
recyclerView.setAdapter(subnetsAdapter);
}else {
//pDialog = new ProgressDialog(getActivity());
//pDialog.setMessage("Retrieving data from Server");
//pDialog.show();
//Instead of a progressdialog, put here a dialog informing that the list is empty!
}
}
});
}

How is described in https://developer.android.com/training/material/lists-cards.html
The overriden method getItemCount() is invoked by the layout manager.
This is the snippet:
// Return the size of your dataset (invoked by the layout manager)
#Override
public int getItemCount() {
return mDataset.length;
}
So to detect if the recyclerView is empty you must request it to your LayoutManager. Example:
if( mLayoutManager.getItemCount() == 0 ){
//Do something
}
I try to getItemCount() of my Adapter but this returns 0, I don't know why it is...

if (adapter.getItemCount() == 0)
doing this worked for me...

You can do it using interface callback:
Create interface
public interface OnAdapterCountListener {
void onAdapterCountListener(int count);
}
Add below variables and methods in adapter
private OnAdapterCountListener onAdapterCountListener;
public void setOnAdapterCountListener(OnAdapterCountListener l) {
onAdapterCountListener = l;
}
Add this line in onCreateViewHolder of your adapter
onAdapterCountListener.onAdapterCountListener(getItemCount());
Finally, call interface in your activity
listAdapter.setOnAdapterCountListener(new OnAdapterCountListener() {
#Override
public void onAdapterCountListener(int count) {
if (count > 0)
adapterEmptyText.setVisibility(View.GONE);
}
});

Create a Class and inherit Recyclerview - Follow the bellowing code
public class RecyclerviewEmpty extends RecyclerView {
private View emptyView;
private final AdapterDataObserver observer = new AdapterDataObserver() {
#Override
public void onChanged() {
checkIfEmpty();
}
#Override
public void onItemRangeInserted(int positionStart, int itemCount) {
checkIfEmpty();
}
#Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
checkIfEmpty();
}
};
public RecyclerviewEmpty(#NonNull Context context) {
super(context);
}
public RecyclerviewEmpty(#NonNull Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
}
public RecyclerviewEmpty(#NonNull Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
private void checkIfEmpty() {
if (emptyView != null && getAdapter() != null) {
final boolean emptyViewVisible = getAdapter().getItemCount() == 0;
emptyView.setVisibility(emptyViewVisible ? VISIBLE : GONE);
setVisibility(emptyViewVisible ? GONE : VISIBLE);
}
}
#Override
public void setAdapter(#Nullable Adapter adapter) {
final Adapter oldAdapter = getAdapter();
if (oldAdapter != null) {
oldAdapter.unregisterAdapterDataObserver(observer);
}
super.setAdapter(adapter);
if (adapter != null) {
adapter.registerAdapterDataObserver(observer);
}
checkIfEmpty();
}
public void setEmptyView(View emptyView) {
this.emptyView = emptyView;
checkIfEmpty();
}
activity_xml - define class name in a View
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#drawable/bg_main"
tools:context=".Ui.FavouriteActivity">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<view
android:id="#+id/rv_fav_activity"
class="com.kumar.random.quotes.Views.RecyclerviewEmpty"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<TextView
android:id="#+id/list_empty1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:gravity="center"
android:text="Empty Favourite"
android:textSize="14sp" />
</FrameLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
Activity.java
private RecyclerviewEmpty rvFavourite;
private void setUpRv() {
rvFavourite.setEmptyView(emptyView);
LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
MainQuotesAdapter adapter = new MainQuotesAdapter(this, favouriteItem);
rvFavourite.setLayoutManager(layoutManager);
rvFavourite.setAdapter(adapter);
}
Please notes_01:
rvFavourite.setEmptyView(emptyView);
Please Notes_02:
public void setEmptyView(View emptyView) {
this.emptyView = emptyView;
checkIfEmpty();
}
Please Notes_03
<view
android:id="#+id/rv_fav_activity"
class="com.kumar.random.quotes.Views.RecyclerviewEmpty"
android:layout_width="match_parent"
android:layout_height="match_parent" />