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Recyclerview.notifyItemInserted() duplicates the list item

I have a requirement, where I should download the ad item while scrolling and update the list. Since calling notifyDatasetChnaged(), resets everything, I'm calling notifyItemInserted(position). But, calling this duplicated the items in the list. I found that there are no repeated items in the list. But after calling notifyItemInserted, it duplicates the item. I'm not getting how to resolve this issue. This what I'm doing:
mNewsList.add(mPreviousAdPosition, newsItem);
mAdapter.notifyItemInserted(mPreviousAdPosition);
If I call, it works properly, there are no repeated items. But I don't want my list items to recreate. What can be the issue ?

I had the same problem for exactly the same use case, the solution is:
Implement this method in your Adapter :
#Override
public long getItemId(int position) {
//Return the stable ID for the item at position
return items.get(position).getId();
}
Call this method in the Constructor of your Adapter :
//Indicates whether each item in the data set can be represented with a unique identifier
setHasStableIds(true);

You can add the object at the end of the array with each object having a position along with it where it needs to be shown in the recycler view. Sort this array on the basis of position before calling notifyItemInserted(position). In this way only required data will be drawn.I have recenlty followed this approach and works very well with dynamic sections added in between in recycler view.

You should add the item at the end of the list.
mNewsList.add(newsItem);
and then notify like this.
mAdapter.notifyItemInserted(mNewsList.size()-1);

Create a temporary list and add items as mentioned below:
List<YourModel> mTmpList = new ArrayList<YourMdel>();
//add items (from 0 -> mPreviousAdPosition) to mTmpList;
for(int i=0; i<mPreviousAdPosition; i++) {
mTmpList.add(mNewsList.get(i));
}
//add item at mPreviousAdPosition
mTmpList.add(newsItem);
//add remaining items and set i<=mNewsList.size() because we ha
for(int i=mPreviousAdPosition; i<=mNewsList.size(); i++) {
mTmpList.add(mNewsList.get(i - 1)); //because we have added item at mPreviousAdPosition;
}
mNewsList = mTmpList;
mAdapter.notifyDataSetChanged();

You code should be written like this:
public class RecyclerViewAdapter extends RecyclerView.Adapter{
...
public void addData(int position, Item newsItem) {
mNewsList.add(position, newsItem);
notifyItemInserted(position);
}
...
}
and then you need to call the fun addData

How to restore to the previous state in RecyclerView after loading more data

I have been working with RecyclerView for a while. I am following lazy loading, so I am showing 10 data on the view each time. If user scroll to the bottom, the page re-load from the TOP! however, I want to stay where it was previously! So, I have tried to use
recyclerView.scrollToPosition(position);
However, this breaks the UI flow!
My second try is using onSaveInstanceState() and onRestoreInstanceState(Bundle state); However, that does not work! My page is re-loads to the top!
Parcelable state = layoutManager.onSaveInstanceState();
layoutManager.onRestoreInstanceState(state);
I have tried every other methods, apparently none is working for me!
Any help would be highly appreciated! Thanks in advance!

Note : Make sure that you are not initialising or calling setAdapter() method each time after updating your dataset. If not, then
You have to update your data list and call notifyDataSetChanged() which will update your adapter from existing position.
Let's say you have stored your data into ArrayList mData;
Your getItemCount() would be
#Override
public int getItemCount() {
if (mData != null && mData.length() > 0)
return mData.size();
return 0;
}
Now create one more method in your adapter which you will called each time whenever you will get new data from server. This method will simply override your dataset and will update your adapter
private void updateDataSet(ArrayList<String> mData){
this.mData = mData;
notifyDataSetChanged();
}

I have done this functionality before 2 days ago
I share my idea with you
Make
Listview lv; //Assume Find view by Id
List<Model> models = new ArrayList();
Now Make an Adapter and assign blank models
CustomAdapter adapter = new CustomeAdapter(context,models);
lv.setAdapter(adapter);
Now when you have new data to load with lazylodaing
do this
models.addAll(newModels); //new ModelList
adapter.notifyDataSetChanged();
Thats it.

This is the default behaviour Recycler View to recycle/resuse views. As in official docs:
https://developer.android.com/reference/android/support/v7/widget/RecyclerView.html
If you are having any view related issues then save your view state in your List<Object> like setting visible item or not per position. And in your onBindViewHolder method as per position show/hide your view.

Best way to update data with a RecyclerView adapter [duplicate]

This question already has answers here:
How to update RecyclerView Adapter Data
(16 answers)
Closed 5 years ago.
When I have to use a classic adapter with a ListView, I update my data in the ListView like this:
myAdapter.swapArray(data);
public swapArray(List<Data> data) {
clear();
addAll(data);
notifyDataSetChanged();
}
I would like to know what is the best practice for a RecyclerView. Because in a RecyclerView adapter you can't do a clear and addAll as in ListView.
So I tried just with a notifyDataSetChanged, but it didn't work.
Then I tried with a swapAdapter on my view:
List<Data> data = newData;
MyRecyclerAdapter adapter = new MyRecyclerAdapter(data);
// swapAdapter on my recyclerView (instead of a .setAdapter like with a classic listView).
recyclerViewList.swapAdapter(adapter, false);
But with this last solution, I still have to create a new instance of my adapter and I feel like it's not the best solution. I should be able just to change my data without a new MyRecyclerAdapter.

RecyclerView's Adapter doesn't come with many methods otherwise available in ListView's adapter. But your swap can be implemented quite simply as:
class MyRecyclerAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
List<Data> data;
...
public void swap(ArrayList<Data> datas)
{
data.clear();
data.addAll(datas);
notifyDataSetChanged();
}
}
Also there is a difference between
list.clear();
list.add(data);
and
list = newList;
The first is reusing the same list object. The other is dereferencing and referencing the list. The old list object which can no longer be reached will be garbage collected but not without first piling up heap memory. This would be the same as initializing new adapter everytime you want to swap data.

#inmyth's answer is correct, just modify the code a bit, to handle empty list.
public class NewsAdapter extends RecyclerView.Adapter<...> {
...
private static List mFeedsList;
...
public void swap(List list){
if (mFeedsList != null) {
mFeedsList.clear();
mFeedsList.addAll(list);
}
else {
mFeedsList = list;
}
notifyDataSetChanged();
}
I am using Retrofit to fetch the list, on Retrofit's onResponse() use,
adapter.swap(feedList);

DiffUtil can the best choice for updating the data in the RecyclerView Adapter which you can find in the android framework. DiffUtil is a utility class that can calculate the difference between two lists and output a list of update operations that converts the first list into the second one.
Most of the time our list changes completely and we set new list to RecyclerView Adapter. And we call notifyDataSetChanged to update adapter. NotifyDataSetChanged is costly. DiffUtil class solves that problem now. It does its job perfectly!

Found following solution working for my similar problem:
private ExtendedHashMap mData = new ExtendedHashMap();
private String[] mKeys;
public void setNewData(ExtendedHashMap data) {
mData.putAll(data);
mKeys = data.keySet().toArray(new String[data.size()]);
notifyDataSetChanged();
}
Using the clear-command
mData.clear()
is not nessescary

RecyclerView change data set

I want to implement search functionality for my RecyclerView. On text changed i want to change the data that are displayed with this widget. Maybe this question has been asked before or is simple, but I don't know how the change the data that is to be shown...
My RecyclerView is defined as follows:
// 1. get a reference to recyclerView
mRecyclerView = (RecyclerView)findViewById(R.id.recyclerView);
// 2. set layoutManger
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
// 3. create an adapter
mAdapter = new ItemsAdapter(itemsData);
// 4. set adapter
mRecyclerView.setAdapter(mAdapter);
And the data that I am showing is something like:
ItemData itemsData[] = { new ItemData("Mary Richards"),
new ItemData("Tom Brown"),
new ItemData("Lucy London")
};
So when when I want to give the adapter another set of data, another array (with one item for example), what should I do?

If you have stable ids in your adapter, you can get pretty good results (animations) if you create a new array containing the filtered items and call
recyclerView.swapAdapter(newAdapter, false);
Using swapAdapter hints RecyclerView that it can re-use view holders. (vs in setAdapter, it has to recycle all views and re-create because it does not know that the new adapter has the same ViewHolder set with the old adapter).
A better approach would be finding which items are removed and calling notifyItemRemoved(index). Don't forget to actually remove the item. This will let RecyclerView run predictive animations. Assuming you have an Adapter that internally uses an ArrayList, implementation would look like this:
// adapter code
final List<ItemData> mItems = new ArrayList(); //contains your items
public void filterOut(String filter) {
final int size = mItems.size();
for(int i = size - 1; i>= 0; i--) {
if (mItems.get(i).test(filter) == false) {
mItems.remove(i);
notifyItemRemoved(i);
}
}
}
It would perform even better if you can batch notifyItemRemoved calls and use notifyItemRangeRemoved instead. It would look sth like: (not tested)
public void filterOut(String filter) {
final int size = mItems.size();
int batchCount = 0; // continuous # of items that are being removed
for(int i = size - 1; i>= 0; i--) {
if (mItems.get(i).test(filter) == false) {
mItems.remove(i);
batchCount ++;
} else if (batchCount != 0) { // dispatch batch
notifyItemRangeRemoved(i + 1, batchCount);
batchCount = 0;
}
}
// notify for remaining
if (batchCount != 0) { // dispatch remaining
notifyItemRangeRemoved(0, batchCount);
}
}
You need to extend this code to add items that were previously filtered out but now should be visible (e.g. user deletes the filter query) but I think this one should give the basic idea.
Keep in mind that, each notify item call affects the ones after it (which is why I'm traversing the list from end to avoid it). Traversing from end also helps ArrayList's remove method performance (less items to shift).
For example, if you were traversing the list from the beginning and remove the first two items.
You should either call
notifyItemRangeRemoved(0, 2); // 2 items starting from index 0
or if you dispatch them one by one
notifyItemRemoved(0);
notifyItemRemoved(0);//because after the previous one is removed, this item is at position 0

This is my answer - thanks to Ivan Skoric from his site: http://blog.lovelyhq.com/creating-lists-with-recyclerview-in-android/
I created an extra method inside my adapter class:
public void updateList(List<Data> data) {
mData = data;
notifyDataSetChanged();
}
Then each time your data changes, you just call this method passing in your new data and your view should change to reflect it.

Just re-initialize your adapter:
mAdapter = new ItemsAdapter(newItemsData);
or if you only need to remove add a few specific items rather than a whole list:
mAdapter.notifyItemInserted(position);
or
mAdapter.notifyItemRemoved(position);

If you want to change the complete Adapter in the recycler view. you can just simply set by recycler.setAdapter(myAdapter);
It will automatically remove the old adapter from recycler view and replace it with your new adapter.

As ygit answered, swapAdapter is interesting when you have to change the whole content.
But, in my FlexibleAdapter, you can update the items with updateDataSet. You can even configure the adapter to call notifyDataSetChanged or having synchronization animations (enabled by default). That, because notifyDataSetChanged kills all the animations, but it's good to have for big lists.
Please have a look at the description, demoApp and Wiki pages: https://github.com/davideas/FlexibleAdapter

Update custom listview item attribute

I am using listview in my app.I am adding items to list with this line:
conversationsAdapter.add(user);
and this initializes list
conversationsAdapter=new ArrayAdapter<JsonObject>(this,0) {
#Override
public View getView(int c_position,View c_convertView,ViewGroup c_parent) {
if (c_convertView == null) {
c_convertView=getLayoutInflater().inflate(R.layout.random_bars,null);
}
JsonObject user=getItem(c_position);
String name=user.get("name").getAsString();
String image_url="http://domain.com/photos/profile/thumb/"+user.get("photo").getAsString();
TextView nameView=(TextView)c_convertView.findViewById(R.id.tweet);
nameView.setText(name);
ImageView imageView=(ImageView)c_convertView.findViewById(R.id.image);
Ion.with(imageView)
.placeholder(R.drawable.twitter)
.load(image_url);
return c_convertView;
}
};
ListView conversationsListView = (ListView)findViewById(R.id.conversationList);
conversationsListView.setAdapter(conversationsAdapter);
conversationsListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
startChat(conversationsAdapter.getItem(position));
}
});
My list view is looking like this:
I want to update an item in the list.How can I do this ?
Example:We can write a method like: changeName when this method calls,method sets name "Tolgay Toklar" to "Tolgay Toklar Test" so I want to update custom listview item attributes.

I totally disagree with tyczj. You never want to externally modify an ArrayAdapter's list and yes it's possible to update just an individual item. Lets start with updating an individual item.
You can just invoke getItem() and directly modify the object and call notifyDataSetChanged(). Example:
JSONObject object = conversationAdapter.getItem(position);
object.put("name", data);
conversationAdapter.notifyDataSetChanged();
Why does this work? Because the adapter will feed you the same object reference used internally, allowing you to modify it and update the adapter. No problem. Of course, I'd recommend instead building your own custom adapter to perform this directly on the adapter's internal list. As an alternative, I highly recommend using the ArrayBaseAdapter instead. It already provides that ability for you while fixing some other major bugs with Android's ArrayAdapter.
So why is tyczj wrong about modifying the external list? Simple. There's no guarantee that your external list is the same as the adapters. Once you perform a filter on the ArrayAdapter, your external list and the adapters are no longer the same. You can get into a dangerous scenario where (for example) index 5 no longer represents position 5 in the adapter because you later added an item to the adapter. I suggest reading Problems with ArrayAdapter's Constructors for a little more insight.
Update: How External List Fails
Lets say you create a List of objects to pass into an ArrayAdapter. Eg:
List<Data> mList = new ArrayList<Data>();
//...Load list with data
ArrayAdapter<Data> adapter = new ArrayAdapter<Data>(context, resource, mList);
mListView.setAdapter(adapter);
So far so good. You have your external list, you have an adapter instantiated with it and assigned to listview. Now lets say at some later point, the adapter is filtered and cleared.
adapter.filter("test");
//...later cleared
adapter.filter("");
Now at this point mList is NOT the same as the adapter. So if the adapter is modified:
adapter.add(newDataObject);
You'll find that mList does not contain that new data object. Hence why external lists like this can be dangerous as the filter creates a NEW ArrayList instance. It won't continue to use your mList referenced one. You could even try adding items to mList at this point and it won't be reflected in the adapter.

If you change the data in your list you need to call notifyDatasetCanged on the adapter to notify the list that the underlying data has changed needs to be updated and.
Example
List<MyData> data = new ArrayList<MyData>();
private void changeUserName(String name){
//find the one you need to change from the list here
.
.
.
data.set(myUpdatedData);
notifyDatasetChanged()
}