Develop Reference

ListAdapter DiffUtils newItem and oldItem the same when submitList() called

Just FYI, I'm not exactly looking for a 'fix' but for an explanation and a discussion that might help understand a little bit more how seemingly silly things like these work.
I was working on this bigger project when I realized that somewhere, a certain list wasn't being updated correctly. Looking a little closer, the items, were correctly being modified, and if you 'scrolled away' and back, the item's information would be displayed correctly.
I stumbled upon this article:
ListAdapter not updating item in RecyclerView
But the difference here, is that in fact, DiffUtils was being called, but somehow the newItem and oldItem were the same! I understand that the library assumes you are using Room or any other ORM which offers a new async list every time it gets updated, but here's the thing. If I submit the list "naively" DiffUtils is not even called. But, if I submit the list as list.toMutableList() like some suggest then, DiffUtils IS called, but somehow the items, new and old, are already the same, hence, nothing gets updated at that moment (verified this by placing breakpoints inside areContentsTheSame).
I leave you here the relevant snippets and a link to a test project I created just so I could encapsulate the behavior and test it separately from everything else.
The Fragment - just calling the submitList
viewModel.items.observe(viewLifecycleOwner) {
adapter.submitList(it.toMutableList())
}
ViewModel
private val _items = MutableLiveData<List<SimpleItem>>()
val items: LiveData<List<SimpleItem>>
get() = _items
init {
_items.value = ItemsRepo.getItems()
}
fun onItemClick(itemId: Int) {
ItemsRepo.addItemCount(itemId)
_items.value = ItemsRepo.getItems()
}
The "Repo" I create some data
object ItemsRepo {
private var items = mutableListOf(
SimpleItem(1),
SimpleItem(2),
SimpleItem(3),
SimpleItem(4),
SimpleItem(5)
)
fun getItems(): List<SimpleItem> {
return items
}
fun addItemCount(itemId: Int) {
items.find { it.itemId == itemId }?.let {
it.itemClickCount += 1
}
}
The GitHub repo:
https://github.com/ellasaro/ListAdapterTest
Cheers!

Don't use mutable data classes or mutable lists with DiffUtil. It can lead to all kinds of problems. DiffUtil relies on comparing two lists, so if one of them is mutable and has been changed, it can't compare old and new successfully because there's no record of the previous state.
I didn't take the time to narrow down your exact issue, but I bet if you change your Repo's getItems() to return items.toList() (so mutating the Repo doesn't mutate downstream lists), and change SimpleItem to be an immutable class, your problems will go away.
Making SimpleItem immutable will be a little bit of hassle, unfortunately. The click listener instead of mutating the item will have to report back to the repo the id of the item that changed, and the repo must manually swap it out, and then you refresh the list.
It will be cleaner if your Repo returns a Flow of lists that automatically emits when changes are reported to it. Then your ViewModel doesn't have to both report changes and then remember to manually query the list state again.
I would use toList() and not toMutableList(). A mutable list communicates that you plan to mutate the list instead of just readding it, which you must never do with a list being passed to a DiffUtil.

Declaring the itemClickCount property as val, and getting the list as an immutable list from the Repo object did the trick as Tenfour04 suggested.
As an additional observation, if I keep the itemClickCount property as var but replace the element altogether and re-submit the updated list, it works correctly. So the problem seems to be modifying the object's mutable property directly in the Repo's list. Using .toList() in getList() didn't help in that case.

Paging 3: How to load list at item position or at item with specific id

I have a list of messages.
Each message has a unique GUID.
My setup is working for normal usage: user clicks on conversation, list opens with all the messages belonging to that conversation, ordered by most recent first.
ConversationFragment
#Override
public void onViewCreated(
#NonNull View view,
#Nullable Bundle savedInstanceState
) {
LifecycleOwner lifecycleOwner = getViewLifecycleOwner();
viewModel = new ViewModelProvider(this).get(ConversationViewModel.class);
viewModel
.getMessageList(lifecycleOwner, conversationId) // conversationId is a global variable
.observe(lifecycleOwner, messagePagingData -> adapter.submitData(
lifecycleOwner.getLifecycle(),
messagePagingData
));
super.onViewCreated(view, savedInstanceState);
}
ConversationViewModel
final PagingConfig pagingConfig = new PagingConfig(10, 10, false, 20);
private final ConversationRepository conversationRepository;
public ConversationViewModel(#NonNull Application application) {
super(application);
conversationRepository = new ConversationRepository(application);
}
public LiveData<PagingData<ItemMessage>> getMessageList(
#NonNull LifecycleOwner lifecycleOwner,
#NonNull String conversationId
) {
return PagingLiveData.cachedIn(
PagingLiveData.getLiveData(new Pager<>(pagingConfig, () -> conversationRepository.getMessageList(conversationId))),
lifecycleOwner.getLifecycle()
);
}
ConversationRepository
private final MessageDao messageDao;
public ConversationRepository(#NonNull Context context) {
AppDatabase database = AppDatabase.getDatabase(context);
messageDao = database.messageDao();
}
public PagingSource<Integer, ItemMessage> getMessageList(#NonNull String conversationId) {
return messageDao.getMessageList(conversationId);
}
MessageDao
#Query(
"SELECT * FROM Message " +
"WHERE Message.conversationId = :conversationId " +
"ORDER BY Message.time DESC"
)
public abstract PagingSource<Integer, ItemMessage> getMessageList(String conversationId);
Now my goal is to be able to open the conversation already scrolled at a specific message.
I also do not want to load the entire conversation and then scroll to the message, some conversations can be very long and I do not want to put the user on an auto scroll that can take ages to reach the specific message.
Ideally the way I envision this being done correct is to pass the message id to be in view, load a chunk of X messages surrounding before and after that message id and then after it is already presented to the user in the RecyclerView it will load more if the user goes up or down.
This is not meant to use network requests, the entire conversation is available in the database already so it will only use the information that is already in the database.
I've tried understanding the examples that use ItemKeyedDataSource or PageKeyedDataSource, but I cannot go anywhere because every single time those examples are in Kotlin only and require Retrofit to work, which I do not use. As it is these examples are completely useless for anyone like me that is in Java and not using Retrofit.
How can this be achieved?
Please provide an answer in Java, not just Kotlin only (kotlin is OK as long as it's in java as well) and please do not suggest new libraries.

As far as I could find the official documentation does not provide any sort of clue on how to solve this one for a Paging + Room integration. In fact, it doesn't provide any solution whatsoever to scroll to an item in a PagingDataAdapter, period.
The only thing that worked for me so far was to run two queries every single time I wish to accomplish this: one to find the item position in the result query list and the other to actually load said list with the initialKey set in the Pager constructor with the value of the item position we queried previously.
And if you're feeling a bit confused, this does not end here, because even the explanation for what is initialKey and how to use it is just not documented. No, seriously: What does the initialKey parameter do in the Pager constructor
So there's two guessing games here: one to find a proper way to lookup the item index from a result list and another to set it up properly in the final query.
I hope the Paging 3 documentation gets improved soon to cover these very basic issues.
In the end this is an example of how I managed to get this problem kind of working for me, even though I have no idea if this is the proper way to do it because, again, their documentation is absolutely lacking in this department.
Create two identical queries for the list results you desire
One of those queries only returns a full list of the results based on a key you'll use to uniquely identify an item. In my case it is messageId.
Load the query in 2 and individually iterate the results list using a for... loop until you find the item you want to know its position in the list. That position is given by the iterator you use in your loop block.
Pass the item position from 3 as initialKey parameter into your Pager builder of the final query
The first chunk of data you'll receive now will contain the item you want
If you want you can now scroll to that item in your RecyclerView, but you'll have to query it from the current list of items loaded in the adapter. See about using the .snapshot() in the PagingAdapter
That's it, now I can finally load an item at a certain position using Paging 3 + Room, with absolutely no idea of whether this is the proper way to do it thanks to the completely absent documentation for this.

Convert RxJava Subjects to Observables

I recently ran into discussion about usage of Subject, like this one here: https://github.com/JakeWharton/RxRelay/issues/7
I see a lot of people saying that Subject should be avoided and some people even say any usage of Subject is inherently a bad practice. While I agree on the theoretical level that Subject can be and should be avoided, I can hardly get rid of subjects in real practices. It seems impractical, or even impossible to do so.
Imagine a simple theoretical weather app that has just two things:
a view that displays current weather information
a refresh button which re-fetch the weather information from the server.
(Let's assume for simplicity that the app does not show the data at initial launch, but waits for the users to press refresh button at least once.)
Then you can think of a view model design like this:
ViewModel
interface IWeatherViewModel {
// Provides weather data
Flowable<WeatherData> getWeatherDataToDisplay();
// Lets view to refresh
void refresh();
}
If I use Subject then IWeatherViewModel can be implemented like this:
class WeatherViewModel implements IWeatherViewModel {
private final BehaviorProcessor<WeatherData> weatherData = BehaviorProcessor.create();
private final PublishProcessor<Boolean> eventRefresh = PublishProcessor.create();
WeatherViewModel() {
eventRefresh
.flatMapSingle(x -> getWeatherData())
.subscribe(weatherData);
}
// Provides weather data
public Flowable<WeatherData> getWeatherDataToDisplay() {
weatherData.hide();
}
// Lets view to refresh
public void refresh() {
eventRefresh.onNext(true);
}
private Single<WeatherData> getWeatherData() {
... // omitted for simplicity
}
}
The idea is to have a PublishProcessor that emits refresh event whenever refresh() is called which is then propagated to a BehaviorSubject. All subscribers that observe getWeatherDataToDisplay() will be notified once getWeatherData() is successful.
However I find it difficult to implement the same thing without Subject.
The app needs to propagate refresh() call to stream. I might be able to replace PublishProcessor using Flowable.create() but it doesn't look clean at all, the best I could do is:
private FlowableEmitter emitter;
private final Flowable<Boolean> eventRefresh = Flowable.create(emitter -> {
this.emitter = emitter;
}, BackpressureStrategy.BUFFER);
public void refresh() {
emitter.onNext(true);
}
Now suddenly I have to have a new instance variable that I cannot make final..
Also I am not able to find any operator that can effectively replace BehaviorProcessor, nor any hot observable that emits the latest item immediately on subscription. This behavior is necessary because the view should be able to detach and re-attach seamlessly, just like LiveData.
If you see any improvement that can be made, or have a different approach to the problem, please share your thougts.

ListAdapter not updating item in RecyclerView

I'm using the new support library ListAdapter. Here's my code for the adapter
class ArtistsAdapter : ListAdapter<Artist, ArtistsAdapter.ViewHolder>(ArtistsDiff()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(parent.inflate(R.layout.item_artist))
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(getItem(position))
}
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
fun bind(artist: Artist) {
itemView.artistDetails.text = artist.artistAlbums
.plus(" Albums")
.plus(" \u2022 ")
.plus(artist.artistTracks)
.plus(" Tracks")
itemView.artistName.text = artist.artistCover
itemView.artistCoverImage.loadURL(artist.artistCover)
}
}
}
I'm updating the adapter with
musicViewModel.getAllArtists().observe(this, Observer {
it?.let {
artistAdapter.submitList(it)
}
})
My diff class
class ArtistsDiff : DiffUtil.ItemCallback<Artist>() {
override fun areItemsTheSame(oldItem: Artist?, newItem: Artist?): Boolean {
return oldItem?.artistId == newItem?.artistId
}
override fun areContentsTheSame(oldItem: Artist?, newItem: Artist?): Boolean {
return oldItem == newItem
}
}
What's happening is when submitList is called the first time the adapter renders all the items, but when submitList is called again with updated object properties it does not re-render the view which has changed.
It re-renders the view as I scroll the list, which in turn calls bindView()
Also, I've noticed that calling adapter.notifyDatasSetChanged() after submit list renders the view with updated values, but I don't want to call notifyDataSetChanged() because the list adapter has diff utils built-in
Can anyone help me here?

Edit: I understand why this happens that wasn't my point. My point is that it at least needs to give a warning or call the notifyDataSetChanged() function. Because apparently I am calling the submitList(...) function for a reason. I am pretty sure people are trying to figure out what went wrong for hours until they figure out the submitList() ignores silently the call.
This is because of Googles weird logic. So if you pass the same list to the adapter it does not even call the DiffUtil.
public void submitList(final List<T> newList) {
if (newList == mList) {
// nothing to do
return;
}
....
}
I really don't understand the whole point of this ListAdapter if it can't handle changes on the same list. If you want to change the items on the list you pass to the ListAdapter and see the changes then either you need to create a deep copy of the list or you need to use regular RecyclerView with your own DiffUtill class.

The library assumes you are using Room or any other ORM which offers a new async list every time it gets updated, so just calling submitList on it will work, and for sloppy developers, it prevents doing the calculations twice if the same list is called.
The accepted answer is correct, it offers the explanation but not the solution.
What you can do in case you're not using any such libraries is:
submitList(null);
submitList(myList);
Another solution would be to override submitList (which doesn't cause that quick blink) as such:
#Override
public void submitList(final List<Author> list) {
super.submitList(list != null ? new ArrayList<>(list) : null);
}
Or with Kotlin code:
override fun submitList(list: List<CatItem>?) {
super.submitList(list?.let { ArrayList(it) })
}
Questionable logic but works perfectly.
My preferred method is the second one because it doesn't cause each row to get an onBind call.

with Kotlin just you need to convert your list to new MutableList like this or another type of list according to your usage
.observe(this, Observer {
adapter.submitList(it?.toMutableList())
})

I had a similar problem but the incorrect rendering was caused by a combination of setHasFixedSize(true) and android:layout_height="wrap_content". For the first time, the adapter was supplied with an empty list so the height never got updated and was 0. Anyway, this resolved my issue. Someone else might have the same problem and will think it is problem with the adapter.

If you encounter some issues when using
recycler_view.setHasFixedSize(true)
you should definitly check this comment:
https://github.com/thoughtbot/expandable-recycler-view/issues/53#issuecomment-362991531
It solved the issue on my side.
(Here is a screenshot of the comment as requested)

According to the official docs :
Whenever you call submitList it submits a new list to be diffed and displayed. This is why whenever you call submitList on the previous (already submitted list), it does not calculate the Diff and does not notify the adapter for change in the dataset.

Wasted so much time to figure out the problem in same case.
But in my situation the problem was that i forgot to specify a layoutManager for my recyclerView: vRecyclerView.layoutManager = LinearLayoutManager(requireContext())
I hope no one will repeat my mistake...

Today I also stumbled upon this "problem".
With the help of insa_c's answer and RJFares's solution I made myself a Kotlin extension function:
/**
* Update the [RecyclerView]'s [ListAdapter] with the provided list of items.
*
* Originally, [ListAdapter] will not update the view if the provided list is the same as
* currently loaded one. This is by design as otherwise the provided DiffUtil.ItemCallback<T>
* could never work - the [ListAdapter] must have the previous list if items to compare new
* ones to using provided diff callback.
* However, it's very convenient to call [ListAdapter.submitList] with the same list and expect
* the view to be updated. This extension function handles this case by making a copy of the
* list if the provided list is the same instance as currently loaded one.
*
* For more info see 'RJFares' and 'insa_c' answers on
* https://stackoverflow.com/questions/49726385/listadapter-not-updating-item-in-reyclerview
*/
fun <T, VH : RecyclerView.ViewHolder> ListAdapter<T, VH>.updateList(list: List<T>?) {
// ListAdapter<>.submitList() contains (stripped):
// if (newList == mList) {
// // nothing to do
// return;
// }
this.submitList(if (list == this.currentList) list.toList() else list)
}
which can then be used anywhere, e.g.:
viewModel.foundDevices.observe(this, Observer {
binding.recyclerViewDevices.adapter.updateList(it)
})
and it only (and always) copies the list if it is the same as currently loaded one.

In my case I forgot to set the LayoutManager for the RecyclerView. The effect of that is the same as described above.

I got some strange behavior. I'm using MutableList in LiveDate.
In kotlin, the following codes don't work:
mViewModel.products.observe(viewLifecycleOwner, {
mAdapter.submitList(it)
})
But, when I change it to it.toList(), it works
mViewModel.products.observe(viewLifecycleOwner, {
mAdapter.submitList(it.toList())
})
Although, "it" was the same list.

For me, this issue appeared if I was using RecyclerView inside of ScrollView with nestedScrollingEnabled="false" and RV height set to wrap_content.
The adapter updated properly and the bind function was called, but the items were not shown - the RecyclerView was stuck at its' original size.
Changing ScrollView to NestedScrollView fixed the issue.

I had a similar problem. The issue was in the Diff functions, which didn't adequately compare the items. Anyone with this issue, make sure your Diff functions (and by extension your data object classes) contain proper comparison definitions - i.e. comparing all fields which might be updated in the new item. For example in the original post
override fun areContentsTheSame(oldItem: Artist?, newItem: Artist?): Boolean {
return oldItem == newItem
}
This function (potentially) does not do what it says on the label: it does not compare the contents of the two items - unless you have overridden the equals() function in the Artist class. In my case, I had not, and the definition of areContentsTheSame only checked one of the necessary fields, due to my oversight when implementing it. This is structural equality vs. referential equality, you can find more about it here

The reason your ListAdapter .submitlist is not called is because the object
you updated still holds the same adress in memory.
When you update an object with lets say .setText it changes the value in the original object.
So that when you check if object.id == object2.id it will return as the same
because the both have a reference to the same location in memory.
The solution is to create a new object with the updated data and insert that in your list. Then submitList will be called and it will work correctly

It solve my problem. I think the best way is not to override submitList but add a new function to add new list.
fun updateList(list: MutableList<ScaleDispBlock>?) {
list?.let {
val newList = ArrayList<ScaleDispBlock>(list)
submitList(newList)
}
}

I also ran into similar issue, my usecase was i had a clickHandler and item will be selected/not selected (toggle on click).
I tried most of the approach from the above answers, only thing that worked is
adapter.submitList(null)
adapter.submitList(modifiedList)
but problem with this is everytime i click on any clickHandler the whole list is being redrawn again which is very ineffecient.
What i did ?
I made a live data that will store last clicked item and observing that live data, we can tell adapter that live data has been updated like below
viewModel.lastClicked.observe(viewLifeCycleOwner, {
adapter.notifyItemChanged(it)
}

Had a VERY similar issue, to this one, and decided to open a new thread and even create a GitHub project to mess around with. Most solutions didn't quite work for me, not even the toMutableList() way. In my case, the problem was solved by using immutable classes and submitting immutable Lists to the Adapter.

For anyone who's scenario is same as mine, I leave my solution, which I don't know why it's working, here.
The solution which worked for me was from #Mina Samir, which is submitting the list as a mutable list.
My Issue scenario :
-Loading a friend list inside a fragment.
ActivityMain attaches the FragmentFriendList(Observes to the livedata of friend db items) and on the same time, requests a http request to the server to get all of my friend list.
Update or insert the items from the http server.
Every change ignites the onChanged callback of the livedata. But, when it's my first time launching the application, which means that there was nothing on my table, the submitList succeeds without any error of any kind, but nothing appears on the screen.
However, when it's my second time launching the application, data are being loaded to the screen.
The solution is, as metioned above, submitting the list as a mutableList.

As has already been mentioned, you cannot submit a List with the same reference because the ListAdapter will see the lists are in the same location and will therefore not be able to use the DiffUtil.
The simplest solution would be to make a shallow copy of the list.
submitList(ArrayList(list))
Be wary converting the List to a MutableList, as that can create conditions for Exceptions and hard to find bugs.

this will work ....
what happen Is when you get the current list you are pointing to the same list at same location

I needed to modify my DiffUtils
override fun areContentsTheSame(oldItem: Vehicle, newItem: Vehicle): Boolean {
To actually return whether the contents are new, not just compare the id of the model.

Using #RJFares first answer updates the list successfully, but doesn't maintain the scroll state. The entire RecyclerView starts from 0th position. As a workaround, this is what I did:
fun updateDataList(newList:List<String>){ //new list from DB or Network
val tempList = dataList.toMutableList() // dataList is the old list
tempList.addAll(newList)
listAdapter.submitList(tempList) // Recyclerview Adapter Instance
dataList = tempList
}
This way, I'm able to maintain the scroll state of RecyclerView along with modified data.

Optimal Soltion:
for Kotlin
var list :ArrayList<BaseModel> = ArrayList(adapter.currentList)
list.add(Item("Content"))
adapter.submitList(list) {
Log.e("ListAdaptor","List Updated Successfully")
}
We should not maintain another base list as adapter.currentList will return a list in which diff is already calculated.
We have to provide a new instance every time a list updated because of DiffUtil
As per android documentation
DiffUtil is a utility class that calculates the difference between two lists and outputs a list of update operations that converts the first list into the second one.
One list is already maintained by AsyncListDiffer which runs the diffutil on the background thread and another one has to be passed using adaptor.submitList()

The way that worked for me is to override the submitList() and create a copy of the incoming list and each item inside it too:
override fun submitList(list: List<Item>?) {
val listCopy =
mutableListOf<Item>().apply {
list?.map {
add(Item(it.id, it.name, it.imageUrl))
}
}
super.submitList(listCopy)
}

I encounter a very similar issue.
After the data list changed, I submit it again, the recycler view doesn't show as I wanted. It shows duplicated items.
I haven't found the root cause, but I find a workaround, that is to set the adapter to recycler view again. I guess this makes recycler viewer forget the memory before and render again correctly.
userNftListFiltered = SOME_NEW_VALUE
binding.nftSendSearchList.adapter = searchNftAdapter //set adapter again
searchNftAdapter.submitList(userNftListFiltered)

Once you have modify the array list, you have to let adapter know that which position that should be change
this code below is working in my case wish it may help
private fun addItem() {
val index = myArrayList.size
val position = myArrayList.size+1
myArrayList.add(
index, MyArrayClass("1", "Item Name")
)
myAdapter.notifyItemInserted(position) // in case of insert
// in case of remove item
// val index = myArrayList.size-1
// myAdapter.notifyItemRemoved(index)
}

just call adapter.notifyDataSetChanged() after differ.submitList

In my case i was using same object(from adadptar) to update Room database.
Create new object to update database and it'll fix the issue.
Example: I was doing this ->
val playlist = adapter.getItem(position)
playlist.name = "new name"
updatePlaylistObjectInRoomDatabase(playlist)
above code will change object in adapter before room database. So no change will be detected by DiffUtil callback.
Now doing this ->
val playlist = adapter.getItem(position)
val newPlaylist = Playlist()
newPlaylist.id = playlist.id
newPlaylist.name = "new name"
updatePlaylistObjectInRoomDatabase(newPlaylist)
Above code will not change anything in adapter list and will only change data in room database. so submitList will have different values DiffUtil callback can detect.
Enjoy the little things :)

This is something naturally expecte to be available on the official API, but as it isn't, this can be a way to deal with it:
fun <T, VH : RecyclerView.ViewHolder> ListAdapter<T, VH>.clearItems() {
submitList(null)
submitList(emptyList())
}

The adapter can not understand that you have some updates, I don't know why!?
I am adding some entities to the list ad I m expected to collect them at the consumption point. But, nothing happens.
As a solution that worked for me you can use the script below:
artistAdapter.submitList(it.toMutableList())

Because the problem lays inside the ListAdapter, I would like to solve it inside the ListAdapter.
Thanks to Kotlin extension, we can write it like:
class MyItemAdapter() :
ListAdapter<Item, RecyclerView.ViewHolder>(ItemDiffCallback) {
// ...
override fun submitList(list: List<Item>?) {
super.submitList(list?.toList())
}
}
It does look like a tricky hack. So I'd like to make a comment too:
super.submitList(list?.toList()) // to make submitList work, new value MUST be a new list. https://stackoverflow.com/a/50031492/9735961
And yes, thank you, RecyclerView developers.

What is good implementation on updating items that shift around a lot in RecyclerView (swapping), and immediate user feedback?

Goal(s):
1: Effortless updating for dynamic items.
Example:
I have a List<T> returned from an API, I use that list in my RecyclerView.Adapter. User swipes to refresh and a new list is returned from the API containing some new items and some updated old items. Now the older list needs to remove duplicate items.
Note: assume all items have an updated attribute that might change if a user interacts with it.
2: Immediate user feedback (this might tie in with goal #1).
Example:
To insert a new item into the RecyclerView.Adapter it needs to be created in an API first. Implementation creates object in the RecyclerView.Adapter and in the API simultaneously. When the new object is returned from the API the immediate object that was previously injected right away into the RecyclerView.Adapter "syncs" with the API response. This way the user sees immediate feedback.
Code Example:
I don't really have anything in mind for Goal #1 BUT for Goal 2 I was thinking something like this maybe inside my ViewHolder? (I have heard that updating / syncing models in Viewholders is not a good practice in general because viewholders recycle):
// JAVA 7
private void createNewObjectToBeInsertedIntoRecyclerView(String data) {
// Pass callback to API and at the same time insert object into adapter
mAdapter.addNewObject(data);
mPresenter.createObject(new SyncRequestCallback() {
#Override
public void onSuccessFromAPI(ModelObject model) {
mAdapter.updateObject(model);
}
});
}
// JAVA 8
private void createNewObjectToBeInsertedIntoRecyclerView(String data) {
// Pass callback to API and at the same time insert object into adapter
mAdapter.addNewObject(data);
mPresenter.createObject((sync) -> { mAdapter.updateObject(model); });
}
This is just off the top of my head and it is definitely bug prone.
How Can I Achieve This?:
Looking for a robust solution here, but something that doesn't involve content providers (if possible).

You should not do anything like that in the ViewHolder, just bind the data you got from the API to the UI.
What you should do is operate on the Adapter
when the new List<T> returns from the API, just make the old list in the adapter to point to this new one (oldList = newList) and call mAdapter.notifyDataSetChanged()
You can do like point 1) but that way updates the whole Adapter. If you know where in the Adapter you have inserted that item (and I assume you know), just call mAdapter.notifyItemInserted(position) or alternatively, if you have already created it the Adapter, call mAdapter.notifyItemChanged(position)