Endless RecyclerView OnScrollListener

EndlessRecyclerOnScrollListener.java

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener {
    public static String TAG = EndlessRecyclerOnScrollListener.class.getSimpleName();

    private int previousTotal = 0; // The total number of items in the dataset after the last load
    private boolean loading = true; // True if we are still waiting for the last set of data to load.
    private int visibleThreshold = 5; // The minimum amount of items to have below your current scroll position before loading more.
    int firstVisibleItem, visibleItemCount, totalItemCount;

    private int current_page = 1;

    private LinearLayoutManager mLinearLayoutManager;

    public EndlessRecyclerOnScrollListener(LinearLayoutManager linearLayoutManager) {
        this.mLinearLayoutManager = linearLayoutManager;
    }

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);

        visibleItemCount = recyclerView.getChildCount();
        totalItemCount = mLinearLayoutManager.getItemCount();
        firstVisibleItem = mLinearLayoutManager.findFirstVisibleItemPosition();

        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false;
                previousTotal = totalItemCount;
            }
        }
        if (!loading && (totalItemCount - visibleItemCount)
                <= (firstVisibleItem + visibleThreshold)) {
            // End has been reached

            // Do something
            current_page++;

            onLoadMore(current_page);

            loading = true;
        }
    }

    public abstract void onLoadMore(int current_page);
}

SampleActivity.java

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

public class SampleActivity extends ActionBarActivity {

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

        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.list);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(linearLayoutManager);
        recyclerView.setOnScrollListener(new EndlessRecyclerOnScrollListener(linearLayoutManager) {
            @Override
            public void onLoadMore(int current_page) {
                // do something...
            }
        });
    }
}

Thanks a lot for this, much appreciated.

when I tried to use the above code, I found one problem: onLoadMore() might be called multiple times! So I have to make modification to this implementation to make sure only one onLoadMore is triggered. here are the changes:

`package com.zfdang.zsmth_android.listeners;

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener {
public static String TAG = EndlessRecyclerOnScrollListener.class.getSimpleName();

private int previousTotal = 0; // The total number of items in the dataset after the last load
private boolean loading = false; // True if we are still waiting for the last set of data to load.
private int visibleThreshold = 2; // The minimum amount of items to have below your current scroll position before loading more.
int firstVisibleItem, visibleItemCount, totalItemCount;

private int current_page = 1;

private LinearLayoutManager mLinearLayoutManager;

public EndlessRecyclerOnScrollListener(LinearLayoutManager linearLayoutManager) {
    this.mLinearLayoutManager = linearLayoutManager;
}

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    super.onScrolled(recyclerView, dx, dy);

    if(dy < 0) return;
    // check for scroll down
    visibleItemCount = recyclerView.getChildCount();
    totalItemCount = mLinearLayoutManager.getItemCount();
    firstVisibleItem = mLinearLayoutManager.findFirstVisibleItemPosition();

    synchronized (this) {
        if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
            // End has been reached, Do something
            current_page++;
            onLoadMore(current_page);
            loading = true;
        }
    }
}


public void setLoading(boolean loading) {
    this.loading = loading;
}

public abstract void onLoadMore(int current_page);

}`

when I'm using this listener, I will call listener.setLoading(false) explicitly to re-enable onLoadMore after loading is finished.

it works pretty well for me.

Will it work when stackFromEnd is set to true ?

                int lastVisibleItem = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
                int totalItem = mAdapter.getItemCount();

                if (lastVisibleItem > totalItem - 2 && dy > 0 && notLoading) {
                    curPage++;
                    onLoadMore(curPage);
                }

@zfdang Why is there a synchronized block in onScrolled()?

i faced an issue like this : "cannot call this method while RecyclerView is computing a layout or scrolling Load More". How should i do?

other questions, do i put

list.clear();
list.addAll(list);
adapter.notifySetDataChanged()

inside loadMore() ?

that error comes, because i put these code inside loadMore()

Thanks so much! excellent

Will it work with orientation changes?

Please note that using this view with a SwipeRefreshLayout can cause some issues... You are going to have to reset the EndlessRecyclerViewScrollListener when you refresh, or else it gets confused and may not work when you continue to try to scroll again. There needs to be a basic reset() method added...

public void reset()
{
    previousTotalItemCount = 0;
    currentPage = 1;
}

If you call this in the onRefresh() of your SwipeRefreshLayout.OnRefreshListener(), it should work properly. It does for me.

@Dooskington your solutions works well for me. Thanks

Its calling two times when RecyclerView not have enough (2 or 3 row) data as height of screen.

I have Updated this file as per my usage. I got problem like its calling two times when RecyclerView not have enough (2 or 3 row) data as height of screen.

This thing is all the way bugged.
It stuck when I use SwipeOnRefresh even with proposet reset.
Eventually employed https://gist.github.com/nesquena/d09dc68ff07e845cc622 this

if (layoutManager.findLastCompletelyVisibleItemPosition() == recyclerAdapter.getItemCount() - 1) {
//load more
}

it works good with activity but I am facing problem with fragment onLoadMore not calling.

how can be resolved this ?

How to use it to scroll a "Horizontal" linearLayoutManager ?

Cool. Useful !
How to use it in horizontal Recyclerview ?

Not working when "visibleThreshold" set to 1 & current_page = 0;. Setting "visibleThreshold" as 2 and current_page = 0, cause an unnecessary "onLoadMore" call. Which is result in bad experience to user if there in not data on 2nd page.

It works. Thanks!
It was not working for me because I was wrapping the recycler view in a scroll view in my layout file. I spent days to find that it was the root cause of the issue and that I should remove the scroll view.

Great work!
I'm using kotlin and i was stuck on this one.
Thank

You should add a reset method:

public void reset(int previousTotal, boolean loading) {
  this.previousTotal = previousTotal;
  this.loading = loading;
}

And call it on onResume() in SampleActivity:

@Override
  public void onResume() {
    super.onResume();
    endlessScrollListener.reset(0, true);
}

Because after you pause the activity and resume again, the condition !loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold) is always false, thus onLoadMore is never called.

Thanks...Worked like a pro

change if (totalItemCount > previousTotal) to if (totalItemCount != previousTotal) will be better for dataset changing.

Thanks, you saved my time

Thanks you