BIW BIW - 24 days ago 13
Android Question

onLoadMoreListener won't stop loading - RecyclerView - Android

I have a user feed where user's posts will be displayed if the current user is following them, at the moment I have the

loadMoreListener
working fine in regards to it loading the next batch of images when they get to the bottom of the
RecyclerView
. But, when I reach the last item (the feeds only shows 50 posts) in the List it'll attempt to load more and cause an
OutOfMemoryException
. I've restricted the size of the list in the adapter, but at the minute I can't seem to work out when the user has hit the very bottom to stop the progress from displaying and to stop the OnLoadMoreListener from triggering. This is what I have tried so far:

Adapter Constructor:

public RecyclerViewAdapterAllFeeds(Context context,
final ArrayList<AllFeedsDataModel> previousPostsList, final boolean profile, RecyclerView recyclerView, final ProgressBar progressBar) {
this.context = context;
this.previousPostsList = previousPostsList;
this.profile = profile;
if(recyclerView.getLayoutManager() instanceof LinearLayoutManager){
final LinearLayoutManager linearLayoutManager = (LinearLayoutManager)recyclerView.getLayoutManager();
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
progressBar.setVisibility(View.VISIBLE);
if (getItemCount() > LOADED_POSTS - 2) {
totalItemCount = getItemCount();
// total_posts = getItemCount();
lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
if (lastVisibleItem <= TOTAL_POSTS) {
if (!loading && totalItemCount <= (lastVisibleItem)) {
if (onLoadMoreListener != null) {
onLoadMoreListener.onLoadMore();
}
loading = true;
}
}
}
}
});
}
}


onLoadMoreListener

adapter = new RecyclerViewAdapterAllFeeds(getActivity(), latestUpdatesList, false, recyclerView, progressBar);
recyclerView.setAdapter(adapter);// set adapter on recyclerview
adapter.setOnLoadMoreListener(new RecyclerViewAdapterAllFeeds.OnLoadMoreListener() {
@Override
public void onLoadMore() {
refreshCount++;
populateRecyclerView(true, refreshCount);
adapter.update(updatesList);
adapter.setLoaded();
System.out.println("load");
}
});
adapter.notifyDataSetChanged();// Notify the adapter
progressBar.setIndeterminate(false);
progressBar.setVisibility(View.INVISIBLE);


My question is how can I stop it loading if the total posts is less than that of the restrictions or to know when the final item is visible?

Answer

First create EndlessRecyclerViewScrollListener.java:

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

public abstract class EndlessRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
    // The minimum amount of items to have below your current scroll position
    // before loading more.
    private int visibleThreshold = 5;
    // The current offset index of data you have loaded
    private int currentPage = 0;
    // The total number of items in the dataset after the last load
    private int previousTotalItemCount = 0;
    // True if we are still waiting for the last set of data to load.
    private boolean loading = true;
    // Sets the starting page index
    private int startingPageIndex = 0;

    RecyclerView.LayoutManager mLayoutManager;

    public EndlessRecyclerViewScrollListener(LinearLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
    }

    public EndlessRecyclerViewScrollListener(GridLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
        visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
    }

    public EndlessRecyclerViewScrollListener(StaggeredGridLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
        visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
    }

    public int getLastVisibleItem(int[] lastVisibleItemPositions) {
        int maxSize = 0;
        for (int i = 0; i < lastVisibleItemPositions.length; i++) {
            if (i == 0) {
                maxSize = lastVisibleItemPositions[i];
            } else if (lastVisibleItemPositions[i] > maxSize) {
                maxSize = lastVisibleItemPositions[i];
            }
        }
        return maxSize;
    }

    // This happens many times a second during a scroll, so be wary of the code you place here.
    // We are given a few useful parameters to help us work out if we need to load some more data,
    // but first we check if we are waiting for the previous load to finish.
    @Override
    public void onScrolled(RecyclerView view, int dx, int dy) {
        int lastVisibleItemPosition = 0;
        int totalItemCount = mLayoutManager.getItemCount();

        if (mLayoutManager instanceof StaggeredGridLayoutManager) {
            int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);
            // get maximum element within the list
            lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);
        } else if (mLayoutManager instanceof LinearLayoutManager) {
            lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
        } else if (mLayoutManager instanceof GridLayoutManager) {
            lastVisibleItemPosition = ((GridLayoutManager) mLayoutManager).findLastVisibleItemPosition();
        }

        // If the total item count is zero and the previous isn't, assume the
        // list is invalidated and should be reset back to initial state
        if (totalItemCount < previousTotalItemCount) {
            this.currentPage = this.startingPageIndex;
            this.previousTotalItemCount = totalItemCount;
            if (totalItemCount == 0) {
                this.loading = true;
            }
        }
        // If it’s still loading, we check to see if the dataset count has
        // changed, if so we conclude it has finished loading and update the current page
        // number and total item count.
        if (loading && (totalItemCount > previousTotalItemCount)) {
            loading = false;
            previousTotalItemCount = totalItemCount;
        }

        // If it isn’t currently loading, we check to see if we have breached
        // the visibleThreshold and need to reload more data.
        // If we do need to reload some more data, we execute onLoadMore to fetch the data.
        // threshold should reflect how many total columns there are too
        if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {
            currentPage++;
            onLoadMore(currentPage, totalItemCount);
            loading = true;
        }
    }

    // Defines the process for actually loading more data based on page
    public abstract void onLoadMore(int page, int totalItemsCount);

}

And then implement in this way:

recyclerView.addOnScrollListener(new EndlessRecyclerViewScrollListener(recyclerView.getLayoutManager()) {
            @Override
            public void onLoadMore(int page, int totalItemsCount) {

                //TODO Add logic for load more posts or show message if posts is ended.

            }
        });
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