How to update RecyclerView Adapter Data

This is a general answer. The various ways to update the adapter data are explained. The process includes two main steps every time:

Update the data set Notify the adapter of the change

Insert single item

Add "Pig" at index 2.

String item = "Pig";
int insertIndex = 2;
data.add(insertIndex, item);
adapter.notifyItemInserted(insertIndex);

Insert multiple items

Insert three more animals at index 2.

ArrayList<String> items = new ArrayList<>();
items.add("Pig");
items.add("Chicken");
items.add("Dog");
int insertIndex = 2;
data.addAll(insertIndex, items);
adapter.notifyItemRangeInserted(insertIndex, items.size());

Remove a single item

Remove "Pig" from the list.

int removeIndex = 2;
data.remove(removeIndex);
adapter.notifyItemRemoved(removeIndex);

Remove multiple items

Remove "Camel" and "Sheep" from the list.

int startIndex = 2; // inclusive
int endIndex = 4;   // exclusive
int count = endIndex - startIndex; // 2 items will be removed
data.subList(startIndex, endIndex).clear();
adapter.notifyItemRangeRemoved(startIndex, count);

Remove all items

Clear the whole list.

data.clear();
adapter.notifyDataSetChanged();

Replace old list with the new list

Clear the old list then add a new one.

// clear old list
data.clear();

// add new list
ArrayList<String> newList = new ArrayList<>();
newList.add("Lion");
newList.add("Wolf");
newList.add("Bear");
data.addAll(newList);

// notify adapter
adapter.notifyDataSetChanged();

The adapter has a reference to data, so it is important that I didn't set data to a new object. Instead, I cleared the old items from data and then added the new ones.

Update single item

Change the "Sheep" item so that it says "I like sheep."

String newValue = "I like sheep.";
int updateIndex = 3;
data.set(updateIndex, newValue);
adapter.notifyItemChanged(updateIndex);

Move a single item

Move "Sheep" from position 3 to position 1.

int fromPosition = 3;
int toPosition = 1;

// update data array
String item = data.get(fromPosition);
data.remove(fromPosition);
data.add(toPosition, item);

// notify adapter
adapter.notifyItemMoved(fromPosition, toPosition);

Code

Here is the project code for your reference. The RecyclerView Adapter code can be found at this answer.

MainActivity.java

public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ItemClickListener {

    List<String> data;
    MyRecyclerViewAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // data to populate the RecyclerView with
        data = new ArrayList<>();
        data.add("Horse");
        data.add("Cow");
        data.add("Camel");
        data.add("Sheep");
        data.add("Goat");

        // set up the RecyclerView
        RecyclerView recyclerView = findViewById(R.id.rvAnimals);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);
        DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(recyclerView.getContext(),
                layoutManager.getOrientation());
        recyclerView.addItemDecoration(dividerItemDecoration);
        adapter = new MyRecyclerViewAdapter(this, data);
        adapter.setClickListener(this);
        recyclerView.setAdapter(adapter);
    }

    @Override
    public void onItemClick(View view, int position) {
        Toast.makeText(this, "You clicked " + adapter.getItem(position) + " on row number " + position, Toast.LENGTH_SHORT).show();
    }

    public void onButtonClick(View view) {
        insertSingleItem();
    }

    private void insertSingleItem() {
        String item = "Pig";
        int insertIndex = 2;
        data.add(insertIndex, item);
        adapter.notifyItemInserted(insertIndex);
    }

    private void insertMultipleItems() {
        ArrayList<String> items = new ArrayList<>();
        items.add("Pig");
        items.add("Chicken");
        items.add("Dog");
        int insertIndex = 2;
        data.addAll(insertIndex, items);
        adapter.notifyItemRangeInserted(insertIndex, items.size());
    }

    private void removeSingleItem() {
        int removeIndex = 2;
        data.remove(removeIndex);
        adapter.notifyItemRemoved(removeIndex);
    }

    private void removeMultipleItems() {
        int startIndex = 2; // inclusive
        int endIndex = 4;   // exclusive
        int count = endIndex - startIndex; // 2 items will be removed
        data.subList(startIndex, endIndex).clear();
        adapter.notifyItemRangeRemoved(startIndex, count);
    }

    private void removeAllItems() {
        data.clear();
        adapter.notifyDataSetChanged();
    }

    private void replaceOldListWithNewList() {
        // clear old list
        data.clear();

        // add new list
        ArrayList<String> newList = new ArrayList<>();
        newList.add("Lion");
        newList.add("Wolf");
        newList.add("Bear");
        data.addAll(newList);

        // notify adapter
        adapter.notifyDataSetChanged();
    }

    private void updateSingleItem() {
        String newValue = "I like sheep.";
        int updateIndex = 3;
        data.set(updateIndex, newValue);
        adapter.notifyItemChanged(updateIndex);
    }

    private void moveSingleItem() {
        int fromPosition = 3;
        int toPosition = 1;

        // update data array
        String item = data.get(fromPosition);
        data.remove(fromPosition);
        data.add(toPosition, item);

        // notify adapter
        adapter.notifyItemMoved(fromPosition, toPosition);
    }
}

Notes

If you use notifyDataSetChanged(), then no animation will be performed. This can also be an expensive operation, so it is not recommended to use notifyDataSetChanged() if you are only updating a single item or a range of items.

Check out DiffUtil if you are making large or complex changes to a list.

Further study

CodePath: Using the RecyclerView

Smart way to update RecyclerView using DiffUtil

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I'm working with RecyclerView and both the remove and the update work well.

Remove: There are four steps to remove an item from a RecyclerView list.remove(position); recycler.removeViewAt(position); mAdapter.notifyItemRemoved(position); mAdapter.notifyItemRangeChanged(position, list.size()); These lines of code work for me. Update the data: The only things I had to do was: mAdapter.notifyDataSetChanged();

You had to do all of this in the Actvity/Fragment code, not in the RecyclerView Adapter code.

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This is what worked for me:

recyclerView.setAdapter(new RecyclerViewAdapter(newList));
recyclerView.invalidate();

After creating a new adapter that contains the updated list (in my case it was a database converted into an ArrayList) and setting that as adapter, I tried recyclerView.invalidate() and it worked.

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You have two options to do this:

Refresh the UI from the adapter:

mAdapter.notifyDataSetChanged();

Or refresh it from the recyclerView itself:

recyclerView.invalidate();

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Another option is to use diffutil. It will compare the original list against the new list and use the new list as the update if there is a change.

Basically, we can use DiffUtil to compare the old data vs. new data and let it call notifyItemRangeRemoved, and notifyItemRangeChanged and notifyItemRangeInserted on your behalf.

A quick example of using diffUtil instead of notifyDataSetChanged:

DiffResult diffResult = DiffUtil
                .calculateDiff(new MyDiffUtilCB(getItems(), items));

//any clear up on memory here and then
diffResult.dispatchUpdatesTo(this);

//and then, if necessary
items.clear()
items.addAll(newItems)

I do the calculateDiff work off the main thread in case it's a big list using AsyncListDiffer

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Update the data of listview, gridview and recyclerview:

mAdapter.notifyDataSetChanged();

Or:

mAdapter.notifyItemRangeChanged(0, itemList.size());

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I've solved the same problem in a different way. I don't have data. I am waiting for it from the background thread, so start with an empty list.

mAdapter = new ModelAdapter(getContext(), new ArrayList<Model>());
// Then when I get data

mAdapter.update(response.getModelList());
// And update it in my adapter

public void update(ArrayList<Model> modelList){
    adapterModelList.clear();
    for (Product model: modelList) {
        adapterModelList.add(model);
    }
   mAdapter.notifyDataSetChanged();
}

That's it.

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The best and the coolest way to add new data to the present data is

 ArrayList<String> newItems = new ArrayList<String>();
 newItems = getList();
 int oldListItemscount = alcontainerDetails.size();
 alcontainerDetails.addAll(newItems);           
 recyclerview.getAdapter().notifyItemChanged(oldListItemscount+1, al_containerDetails);

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I would suggest you to explore DiffUtil. It also improves RecyclerView's performance while handling list updates.

Define a variable inside your Adapter: differList = AsyncListDiffer(this, this.callback); differList.submitList(list)

Here, the list can be your initial raw list, or simply an empty list provided that you will be updating it later on.

Implementing callback: private val callback : DiffUtil.ItemCallback = object: DiffUtil.ItemCallback() { override fun areItemsTheSame(oldItem: Item, newItem: Item) = oldItem.id == newItem.id override fun areContentsTheSame(oldItem: Item, newItem: Item) = oldItem == newItem } Also, in the same adapter you will have some public function to set the list. fun setData(list: List) { differList.submitList(list) //yeah, that's it! }

Now, after you made any changes to your list(insert/update/delete), just invoke this setData(list) from your fragment/activity. mAdapter.setData(list)

Easy, right?

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These methods are efficient and good to start using a basic RecyclerView.

private List<YourItem> items;

public void setItems(List<YourItem> newItems)
{
    clearItems();
    addItems(newItems);
}

public void addItem(YourItem item, int position)
{
    if (position > items.size()) return;

    items.add(item);
    notifyItemInserted(position);
}

public void addMoreItems(List<YourItem> newItems)
{
    int position = items.size() + 1;
    newItems.addAll(newItems);
    notifyItemChanged(position, newItems);
}

public void addItems(List<YourItem> newItems)
{
    items.addAll(newItems);
    notifyDataSetChanged();
}

public void clearItems()
{
    items.clear();
    notifyDataSetChanged();
}

public void addLoader()
{
    items.add(null);
    notifyItemInserted(items.size() - 1);
}

public void removeLoader()
{
    items.remove(items.size() - 1);
    notifyItemRemoved(items.size());
}

public void removeItem(int position)
{
    if (position >= items.size()) return;

    items.remove(position);
    notifyItemRemoved(position);
}

public void swapItems(int positionA, int positionB)
{
    if (positionA > items.size()) return;
    if (positionB > items.size()) return;

    YourItem firstItem = items.get(positionA);

    videoList.set(positionA, items.get(positionB));
    videoList.set(positionB, firstItem);

    notifyDataSetChanged();
}

You can implement them inside of an Adapter Class or in your Fragment or Activity but in that case you have to instantiate the Adapter to call the notification methods. In my case I usually implement it in the Adapter.

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I found out that a really simple way to reload the RecyclerView is to just call

recyclerView.removeAllViews();

This will first remove all content of the RecyclerView and then add it again with the updated values.

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I strongly recommend you to use [DiffUtil.ItemCallback][1] to handle the change in RecyclerView.Adapter:

fun setData(data: List<T>) {
    val calculateDiff = DiffUtil.calculateDiff(DiffUtilCallback(items, data))
    items.clear()
    items += data
    calculateDiff.dispatchUpdatesTo(this)
}

Under the hood it handles most of the things with AdapterListUpdateCallback:

/**
 * ListUpdateCallback that dispatches update events to the given adapter.
 *
 * @see DiffUtil.DiffResult#dispatchUpdatesTo(RecyclerView.Adapter)
 */
public final class AdapterListUpdateCallback implements ListUpdateCallback {
    @NonNull
    private final RecyclerView.Adapter mAdapter;

    /**
     * Creates an AdapterListUpdateCallback that will dispatch update events to the given adapter.
     *
     * @param adapter The Adapter to send updates to.
     */
    public AdapterListUpdateCallback(@NonNull RecyclerView.Adapter adapter) {
        mAdapter = adapter;
    }

    /** {@inheritDoc} */
    @Override
    public void onInserted(int position, int count) {
        mAdapter.notifyItemRangeInserted(position, count);
    }

    /** {@inheritDoc} */
    @Override
    public void onRemoved(int position, int count) {
        mAdapter.notifyItemRangeRemoved(position, count);
    }

    /** {@inheritDoc} */
    @Override
    public void onMoved(int fromPosition, int toPosition) {
        mAdapter.notifyItemMoved(fromPosition, toPosition);
    }

    /** {@inheritDoc} */
    @Override
    public void onChanged(int position, int count, Object payload) {
        mAdapter.notifyItemRangeChanged(position, count, payload);
    }
}

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I got the answer after a long time:

SELECTEDROW.add(dt);
notifyItemInserted(position);
SELECTEDROW.remove(position);
notifyItemRemoved(position);

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With Kotlin I would use, The Adapter.,

class ProductAdapter(var apples: List<Apples>?= null) : RecyclerView.Adapter<ProductViewHolder>() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductViewHolder {...}

    override fun onBindViewHolder(holder: ProductViewHolder, position: Int) {...}

    override fun getItemCount(): Int {...}

    fun setData(newApples: List<Apples>) {
        apples = newApples
    }
}

In Fragment/Activity

val appleAdapter = ProductAdapter()

val recyclerView = binding.appleRecycler // or findViewById or synthetics or whatever. 
recyclerView.adapter = appleAdapter
recyclerView.layoutManager = LinearLayoutManager(requireContext())

Now handling the data changes in fragment

fun updateRecyclerData(apples: List<Apples>){
    adapter.setData(apples)
    adapter.notifyDataSetChanged()
}

updateRecyclerData(applesList)

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This works fine Try it.

  ArrayList.remove(position);
  notifyItemRemoved(position);
  notifyDataSetChanged();

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If nothing mentioned in the above comments is working for you, it might mean the problem lies somewhere else.

One place I found the solution was in the way I was setting the list to the adapter. In my activity the list was a instance variable and I was changing it directly when any data changed. Due to it being a reference variable there was something weird going on.

So I changed the reference variable to a local one and used another variable to update data and then pass to addAll() function mentioned in the previous answers.

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