Few days ago, I asked this question for avoiding repetition of reycylerview items whose accepted answer helped me to avoid data repetition.
But now I am facing new problems like: not showing all items sometimes only one like this . The real problem is even after getting all items from server properly data is not shown in recyclerView properly .Data are skipped randomly. I don't understand where the problem is. I even tried to use for loop instead of foreach but result was not different. Can anyone please help to fix this? It has been pain in the neck from last one week.
Code:
private List<TimelineData> timelineDataList=new ArrayList<>() ;
public void onCreateView(){
recyclerview.setLayoutManager(new LinearLayoutManager(ctx));
//Setting Adapter
adapter=new CustomRecyclerViewAdapter(timelineDataList);
recyclerview.setAdapter(adapter);
}
#Override
public void onStart() {
super.onStart();
// Fetching data from server
socket.disconnect();
socket.connect();
//Getting Data from server
JSONObject obj=new JSONObject();
try {
obj.put("timeline_posts","all");
socket.emit("data",obj);
} catch (JSONException e) {
e.printStackTrace();
}
}
void addTimelineData(String type,String time,String img_link){
boolean isRepeated = false;
for(TimelineData data : timelineDataList){
if(data.getTime().equals(time)){
isRepeated = true;
}
}
if(!isRepeated){
timelineDataList.add(new TimelineData(type,time,img_link));
}
adapter.notifyDataSetChanged();
}
private Emitter.Listener handlePosts = new Emitter.Listener(){
#Override
public void call(final Object... args){
try {
JSONArray jsonArray=(JSONArray)args[0];
timelineDataList.clear(); //clear data before inserting new one
for(int i=0;i<jsonArray.length();i++){
try {
JSONObject ob=jsonArray.getJSONObject(i);
post_type=ob.getString("post_type");
post_time=ob.getString("time");
post_link=ob.getString("img_link");
addTimelineData(post_type,post_time,post_link);
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (Exception e) {
Log.e("error",e.toString());
}
}
};
Adapter Code:
#Override
public void onBindViewHolder( CustomRecyclerViewHolder holder, int position) {
//Fetching TimelineData
TimelineData timelineData=totalList.get(position);
///Here I'm getting and converting array of image links which are there in jsonObject to arraylist
//Getting Imglink
Gson gson=new Gson();
Type type = new TypeToken<ArrayList<String>>() {}.getType();
ArrayList<String> arrayList = gson.fromJson(timelineData.getImg_link(), type);
//Setting ViewPager
CustomPagerAdapter adp=new CustomPagerAdapter(arrayList);
pager.setAdapter(new PagerAdapter() {
#Override
public int getCount() {
return 0;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return false;
}
});
holder.pager.setCurrentItem(position, false);
holder.pager.clearAnimation();
adp.notifyDataSetChanged();
holder.pager.setAdapter(adp);
holder.pager.setOffscreenPageLimit(1);
}
You are using notifyDataSetChnaged() very quickly, change notify method by this. So that you notify only selected item which you inserted.
Recommended method : You will put below code in your adapter and call this method from for loop where you were setting notifyDataSetChnaged here String s will be replaced by your model class. By this way you just notify only one element when inserting one element. This will also create some inserting animation automatically.
public void insertItemInList(String s) {
if (list == null) list = new ArrayList<>();
list.add(s);
notifyItemInserted(list.size() - 1);
}
Or
You can call notify outside for loop when your work is done like this.
for(int i=0;i<jsonArray.length();i++) {
try {
JSONObject ob=jsonArray.getJSONObject(i);
post_type=ob.getString("post_type");
post_time=ob.getString("time");
post_link=ob.getString("img_link");
addTimelineData(post_type,post_time,post_link);
} catch (JSONException e) {
e.printStackTrace();
}
}
adapter.notifyDataSetChanged();
Issue is that you are notifying adapter rapidly, it can also lead to UI inconsistency.
Let me know if this resolves your issue.
You are modifying the data list in the non-UI thread which could cause problems in the RecyclerView. Instead, you should collect all the data in tempTimelineDataList at once and update the adapted timelineDataList in the UI thread.
Related
How can I keep my scroll position when I refresh my data in my RecyclerView ?
The problem in my code, is that the data I get is coming from an API, and now when I refresh my data, I use the clear() method to delete the current data, and I use a getData () method to retrieve the new data.
getData method :
private void getData() {
JsonArrayRequest arrayRequest = new JsonArrayRequest(url_get, response -> {
JSONObject jsonObject;
for (int i = 0; i < response.length(); i++) {
try {
jsonObject = response.getJSONObject(i);
Category cat = new Category();
cat.setId(jsonObject.getString("id"));
cat.setCategory(jsonObject.getString("name"));
cat.setPvisited(jsonObject.getString("person_visited"));
cat.setCompany(jsonObject.getString("company"));
cat.setDate(jsonObject.getString("date"));
category.add(cat);
} catch (JSONException e) {
e.printStackTrace();
}
}
adapterPush(category);
refresh.setRefreshing(false);
}, error -> {
});
RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
requestQueue.add(arrayRequest);
}
category detail :
private final ArrayList<Category> category = new ArrayList<>();
onRefresh method :
#Override
public void onRefresh() {
category.clear();
getData();
}
I think the getdata() method has a problem, when I remove
category.clear();
of my code, the data is added to the string but the position still returns to the beginning.
Or maybe I should used other thing like a refresh method rather than clear() ?
category.clear();
recyclerview.notifyDataSetChanged();
I'm developing a wallpaper app using mongodb. I'm retrieving data from database and displaying it on my recyclerView by the help of a data-model class without any problem. Also I'm using swipe refresh layout to allow user for refreshing the recyclerView for new data.
But now the problem is how can I avoid data repetition and show only new posts to the user. I meant if there are 5 pics are there in my db in my first query I'll get those 5 so when the user will refresh the layout again the recyclerView's item is increased to 10 and I wanna avoid this I want to show them new pics only when the posts in db will be increased to 6 or more.
I think this data avoid concept is also used in social media apps. but for this context I wonder what I have to do?
Data model class:
public class TimelineData {
private String type, time, img_link;
public TimelineData(String type, String time, String img_link) {
this.type = type;//type means what type of wallpaper
this.time = time;
this.img_link = img_link;
}
public String getType() {
return type;
}
public String getTime() {
return time;
}
public String getImg_link() {
return img_link;
}
}
Adding Data to recyclerview:
private List<TimelineData> timelineDataList = new ArrayList<>();
public void onCreateView() {
recyclerview.setItemViewCacheSize(20);
recyclerview.setDrawingCacheEnabled(true);
recyclerview.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
recyclerview.setLayoutManager(new LinearLayoutManager(ctx));
//Setting Adapter
adapter=new CustomRecyclerViewAdapter(timelineDataList);
recyclerview.setAdapter(adapter);
}
#Override
public void onStart() {
super.onStart();
// Fetching data from server
socket.disconnect();
socket.connect();
//Getting Data from server
JSONObject obj=new JSONObject();
try {
obj.put("timeline_posts","all");
socket.emit("data",obj);
} catch (JSONException e) {
e.printStackTrace();
}
}
void addTimelineData(String type,String time,String img_link) {
timelineDataList.add(new TimelineData(type,time,img_link));
adapter.notifyDataSetChanged();
}
private Emitter.Listener handlePosts = new Emitter.Listener() {
#Override
public void call(final Object... args){
try {
JSONArray jsonArray=(JSONArray)args[0];
for(int i=0;i<jsonArray.length();i++){
try {
JSONObject ob=jsonArray.getJSONObject(i);
post_type=ob.getString("post_type");
post_time=ob.getString("time");
post_link=ob.getString("img_link");
addTimelineData(post_type,post_time,post_link);
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (Exception e) {
Log.e("error",e.toString());
}
}
};
You can try cleaning the data source whenever you get new data, that way you'll always reinsert the complete dataset, if you have new data it will be inserted with the old one and you don't have to worry about repeated data in the mobile app, only in the server.
private List<TimelineData> timelineDataList=new ArrayList<>() ;
public void onCreateView(){
recyclerview.setLayoutManager(new LinearLayoutManager(ctx));
//Setting Adapter
adapter=new CustomRecyclerViewAdapter(timelineDataList);
recyclerview.setAdapter(adapter);
}
#Override
public void onStart() {
super.onStart();
// Fetching data from server
socket.disconnect();
socket.connect();
//Getting Data from server
JSONObject obj=new JSONObject();
try {
obj.put("timeline_posts","all");
socket.emit("data",obj);
} catch (JSONException e) {
e.printStackTrace();
}
}
void addTimelineData(String type,String time,String img_link){
boolean isRepeated = false;
for(TimelineData data : timelineDataList){
if(data.getTime().equals(time)){
isRepeated = true;
}
}
if(!isRepeated){
timelineDataList.add(new TimelineData(type,time,img_link));
}
adapter.notifyDataSetChanged();
}
private Emitter.Listener handlePosts = new Emitter.Listener(){
#Override
public void call(final Object... args){
try {
JSONArray jsonArray=(JSONArray)args[0];
timelineDataList.clear(); //clear data before inserting new one
for(int i=0;i<jsonArray.length();i++){
try {
JSONObject ob=jsonArray.getJSONObject(i);
post_type=ob.getString("post_type");
post_time=ob.getString("time");
post_link=ob.getString("img_link");
addTimelineData(post_type,post_time,post_link);
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (Exception e) {
Log.e("error",e.toString());
}
}
};
before you add new elements to the wallpaper list, check to see if an object with that id exist in the list. if it does, skip it, else add it.
I am building an application that is pretty dependent on async requests to function.
I have the main Activity called MainActivity. This really doesn't do much apart from contain layouts, however it does have a recycleviewer.
I then have a couple of http requests that are done to populate the recycle viewer.
To do this I have wrote a java class as follows:
public class dataforUi extends AsyncTask<String, String, JsonObject> {
private ArrayList<UiElements> els;
protected void onPreExecute() {
progressDialog.setMessage("Downloading your data...");
progressDialog.show();
progressDialog.setOnCancelListener(new DialogInterface.OnCancelListener() {
public void onCancel(DialogInterface arg0) {
RedditRequests.this.cancel(true);
}
});
}
protected JsonObject doInBackground(String... params) {
Do the http request here, get the result and populate uiElements with it
}
#Override
protected void onPostExecute(JsonObject jsonObject) {
super.onPostExecute(jsonObject);
progressDialog.hide();
}
I have a few more classes like this but hopefully it serves as an example of what I'm trying to do.
Then back in Main Activity, I have this code:
public void getUiElements() {
dataforUi ui = new dataforUi(findViewById(android.R.id.content));
try {
ui.execute("https://t").get();
ArrayList<UiElements> r = ui.getEls();
Log.d("MainFeedScreen", "Size of r is:" + r.size());
UiAdapter = new UiAdapter(r);
mRecyclerView.setAdapter(UiAdapter);
} catch (Exception e) {
}
}
This works fine, but it is very jolty due to the use of .get() on execute to make it blocking. If i remove .get() the progress bar shows up and disappears when the task is done, but my ui thread has progressed past this and ha tried to populate my view with an Empty Array and therefore nothing shows.
I have done a bit of looking into it but cant find a conclusive way of managing the notification of the UI thread that an activity is done.
Would really appericiate any advice on this one.
You need to fix your design.
On post execute, use local broadcast to notify your MainActivity that the AsyncTask is done.
Try using a separate thread to process your data. I use a ListView in stead of a RecyclerView, but the principle is the same.
I have no problems with jolting views.
protected void onPostExecute(String result) {
final String value = result;
// dismiss the dialog after getting all data
progressDialog.dismiss();
if (!value.isEmpty()) {
// updating UI from a new thread
runOnUiThread(new Runnable() {
public void run() {
// ListData is my custom class that holds my data
ArrayList<ListData> arrayDriverListData = new ArrayList<ListData>();
ListDataAdapter adapter = new ListDataAdapter(ListActivity.this, arrayListData);
ListData data;
boolean b = true;
try {
// My data is from a Json source from node 'history'
JSONObject object = new JSONObject(value);
JSONArray array = object.getJSONArray("history");
int len = array.length();
if (len > 0) {
for (int i = 0; i < len; i++) {
final JSONObject o = array.getJSONObject(i);
// Parse my data and add it to my adapter
adapter.add(data);
}
}
} catch (JSONException jex) {
Log.e(TAG, "" + jex.getMessage());
}
// setListAdapter is my call to update my list view
setListAdapter(adapter);
}
});
}
}
Now just update the UI thread
private void setListAdapter(ListDataAdapter adapter){
// my ListView
lvHistory.setAdapter(adapter);
}
I have populated data from server in UI through realm and volley.
Is it possible to store that data locally and show in UI from local db? And how to do it?
Any example would be very helpful.Thanks.
Actually I am trying to get the data locally after fetching and populating the data from the server like this.
if(realm!=null){
Log.d(AppConstants.TAG, "realm fetching");
RealmResults<SellerProducts> sellerProductItems=realm.where(SellerProducts.class).findAll();
adapter.setData(sellerProductItems);
adapter.notifyDataUpdate();
}else {
//network fetch operation
// getting data
//populating data like this
sellerProductItems= gson.fromJson(products.toString(), new TypeToken<List<SellerProducts>>(){}.getType());
//Products is from server response
realm.beginTransaction();
realm.copyToRealmOrUpdate(sellerProductItems);
realm.commitTransaction();
adapter.setData(sellerProductItems);
adapter.notifyDataUpdate();
}
Is it correct?
To save data in realm create a realm object and do Transaction like this
myRealm.beginTransaction();
// Create an object
Country country1 = myRealm.createObject(Country.class);
country1.setName("Norway");
country1.setPopulation(5165800);
country1.setCode("NO");
myRealm.commitTransaction();
To read the data saved
RealmResults<Country> results1 =
myRealm.where(Country.class).findAll();
for(Country c:results1) {
Log.d("results1", c.getName());
}
For complete information visit
http://code.tutsplus.com/tutorials/up-and-running-with-realm-for-android--cms-25241
No, you're completely wrong. If you're doing it right, realm can never be null at that point in your code.
Anyways it works vaguely like this (based on this):
public class GsonRequest<T extends RealmObject> extends Request<T> {
private final Gson gson = new Gson();
private final Listener<T> listener;
/**
* Make a GET request and return a parsed object from JSON.
*
* #param url URL of the request to make
*/
public GsonRequest(Method method, String url,
Listener<T> listener, ErrorListener errorListener) {
super(method, url, errorListener);
this.listener = listener;
}
#Override
protected void deliverResponse(T response) {
listener.onResponse(response);
}
#Override
protected Response<T> parseNetworkResponse(NetworkResponse response) {
try {
String json = new String(
response.data,
HttpHeaderParser.parseCharset(response.headers));
final List<T> result = gson.fromJson(json, new TypeToken<ArrayList<T>>() {}.getType());
Realm realm = null;
try {
realm = Realm.getInstance(realmConfiguration); //get realm config
realm.executeTransaction(new Realm.Transaction() {
for(T t : result) {
realm.copyToRealmOrUpdate(t);
}
});
} finally {
if(realm != null) {
realm.close();
}
}
return Response.success(null, //returning null because
//Realm handles all reload of data on UI thread
HttpHeaderParser.parseCacheHeaders(response));
} catch (UnsupportedEncodingException e) {
return Response.error(new ParseError(e));
} catch (JsonSyntaxException e) {
return Response.error(new ParseError(e));
}
}
}
And
Realm realm;
RealmResults<SellerProducts> results;
final RealmChangeListener<RealmResults<SellerProducts>> realmChangeListener;
SellerProductsAdapter adapter;
#Override
public void onCreate(Bundle bundle) {
super.onCreate(bundle);
realm = Realm.getInstance(this);
results = realm.where(SellerProducts.class).findAll();
realmChangeListener = new RealmChangeListener<RealmResults<SellerProducts>>() {
#Override
public void onChange(RealmResults<SellerProducts> element) {
adapter.notifyDataSetChanged();
}
}
setContentView(R.layout.retrofit_is_better_than_volley);
ListView whyIsThisNotRecyclerView = (ListView) findViewById(R.id.not_recycler_for_some_reason_view);
adapter = new SellerProductsAdapter(this, results);
whyIsThisNotRecyclerView.setAdapter(adapter);
results.addChangeListener(realmChangeListener);
}
#Override
public void onDestroy() {
if(results != null && results.isValid()) {
results.removeChangeListener(realmChangeListener);
}
if(realm != null) {
realm.close();
}
super.onDestroy();
}
And then something like
GsonRequest<SellerProducts> request = new GsonRequest(Method.GET, url,
new Response.Listener<SellerProducts>() {
#Override
public void onResponse(SellerProducts nullObject) {
// hide dialog or something
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
Log.d(TAG, "Error: " + error.getMessage()/*, exception? */);
// hide dialog or something
}
});
//add to request queue
If you are planning to bring Realm to your production code, it takes more than what is discussed here, Realm is a major library and there are also some limitations like Realm, RealmObject and RealmResults can not be passed across threads.
To solve this problem, you need a good architecture, where Realm is isolated from rest of the code. Create a realmModel for each jsonModel and a DAO (Data Access Object). All Realm related calculations should be part of DAO, so that none of your code base needs to know about Realm.
Here is an article about Realm best practices with a good architechture https://medium.com/#Viraj.Tank/realm-integration-in-android-best-practices-449919d25f2f
Also a sample project demonstrating Integration of Realm on Android with MVP(Model View Presenter), RxJava, Retrofit, Dagger, Annotations & Testing. https://github.com/viraj49/Realm_android-injection-rx-test
I have to refresh my listview every 3 seconds (I'm in ListFragment) so I start a new Thread wich start runOnUiThread to edit UI.
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
new Thread(new Runnable() {
public void run() {
do{
ObjectMapper mapper = new ObjectMapper();
VideoData element = null;
try {
element = mapper.readValue(new URL("http://192.168.4.111:3232/videodata.json").openStream(), VideoData.class);
} catch (Exception e) {
e.printStackTrace();
}
final VideoData newData = element;
getActivity().runOnUiThread(new Runnable() {
#Override
public void run() {
hd = newData.getChildren().get(0).getChildren().get(id);
vba.notifyDataSetChanged();
}
});
try {
Thread.sleep(3*1000);
} catch (InterruptedException e) {}
}while(true);
}
}).start();
setAdapter();
}
I parse data on web, and update the reference.
private void setAdapter()
{
if(id == 0)
hd = hd.getChildren().get(0);
vba = new ValueBaseAdapter(getActivity(), 0, hd.getChildren());
setListAdapter(vba);
}
I saw that when notifyDataSetChanged is called, getView is called (and it's ok) but I have old reference, the one of when I called setAdapter the first time.
Also If I set null hd in run(), doesn't change anything, listview doesn't change.
Where is the error? Thanks.
It seems that notifyDataSetChanged() updates adapter's data only if you work with List