RecyclerView scroll to position when a new item is added

Question

I want my RecyclerView to scroll to the bottom when a new item is added to the list. Below is my code:

RecyclerView.LayoutManager layoutManager = new LinearL         


        

Answer 1

This is working for me.

adapter.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
        override fun onChanged() {
            super.onChanged()
            if (canShowLive()) wvl_log_rv.scrollToPosition(adapter.itemCount - 1)
        }
 })

Tested & Verified

Answer 2

This was the solution I came up with, which was good enough for the basics, and didn't require any custom adapters.

myAdapter.registerAdapterDataObserver(object :
        RecyclerView.AdapterDataObserver() {
        override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
            myRecyclerView.scrollToPosition(positionStart)
        }
    })

Answer 3

If want to add the data to the bottom of the list you need to use setStackFromEnd() in RecyclerView Layout Manager.

But first, you need to fix your Adapter. You must not pass your RecylerView to your Adapter. So the following code is wrong:

...
// This is wrong!!
adapter = new RecyclerViewAdapter(data, recyclerView);

recyclerView.setAdapter(adapter);

You need to change your Adapter constructor to only receive the data as its parameter. Something like this:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

  private List<Data> mData;

  public RecyclerViewAdapter(List<Data> data) {
    this.mData = data;
  }

  ...
}

Then you can set the data to always added at the last bottom with the following code:

LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setStackFromEnd(true);
recyclerView.setLayoutManager(linearLayoutManager);

adapter = new RecyclerViewAdapter(data);
recyclerView.setAdapter(adapter);

To add the new data, you better to make a new method in the adapter. Something like this:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

  private List<Data> mData;
  ...

  public void addItem(Data datum) {
    mData.add(datum);
    notifyItemInserted(mData.size());
  }
}

Whenever you have adding a new data, you need to scroll to the bottom with scrollToPosition method. Something like this:

adapter.addItem(newData);
recyclerView.scrollToPosition(adapter.getItemCount() - 1);

Remember that you need to override getItemCount() in your Adapter. It should be something like this:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

  private List<Data> mData;
  public RecyclerViewAdapter(List<Data> data) {
    this.mData = data;
  }

  // Return the total count of items
  @Override
  public int getItemCount() {
    return mData.size();
  }

  ...
}

Please be aware that I'm using a Data pojo as a sample here. You need to change it according to your data type.

Answer 4

adapter.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
    override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
        super.onItemRangeInserted(positionStart, itemCount)

        val msgCount = adapter.getItemCount()
        val lastVisiblePosition = 
            linearLayoutManager.findLastCompletelyVisibleItemPosition()

        if (lastVisiblePosition == -1 || positionStart >= msgCount - 1 && 
            lastVisiblePosition == positionStart - 1) {
            recyclerView.scrollToPosition(positionStart)
        } else {
            recyclerView.scrollToPosition(adapter.getItemCount() - 1);
        }
    }
})

Answer 5

ישו אוהב אותך's solution worked on other projects. But setting recyclerView.scrollToPosition() didn't work for me. This is what finally did the job:

public void addNewCard() {
    data.add("New");
    adapter.notifyItemInserted(data.size());

    scrollView.post(new Runnable() {
        @Override
        public void run() {
            scrollView.scrollTo(0,buttonAddNewItem.getTop());
        }
    });
}

Answer 6

This is happening because your

recyclerView.scrollToPosition(data.size() - 1);

is getting called first and then the list is being initialized. You need to add this line after your recycler View view is initialized. You can add this line in a handler.