CODEWITHSUNDEEP
androidxamarinandroid-recyclerviewxamarin.android
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Reputation: 922

RecyclerView crashes when scroll and reload happens at the same time

In my app I am using a RecyclerView, that is supposed to continue loading images when the user scrolls down. But this brought me to an issue I couldn't resolve. Basically, I saying 

        loadPhotos.LoadMoreItems(3);

which means, load 3 photos to begin with. As soon as a certain point is reached (via scrolling) continue loading another 3 pictures (which make up one row):

        var onScrollListener = new XamarinRecyclerViewOnScrollListener(mLayoutManager);
        onScrollListener.LoadMoreEvent += (object sender, EventArgs e) => 
        {
            int oldCount = loadPhotos.pictures.Count;
            loadPhotos.LoadMoreItems(3);
            mAdapter.NotifyItemRangeChanged(oldCount - 1, loadPhotos.pictures.Count);
        };

If I only load 3 photos, to begin with, the phone loads 3 photos and a split-second after, it loads the next row, because the position is reached. So this does in fact work, but If I would start scrolling I get this error:

 “cannot call this method while RecyclerView is computing a layout or scrolling”

On this line:

mAdapter.NotifyItemRangeChanged(oldCount - 1, loadPhotos.pictures.Count);

Another interesting fact is, that I can get this to work on small phones, but phones with a larger screen (Samsung s8) will have a crash sooner.

So, I am really confused on how to do all that. Just as extra info, this is my whole activity:

    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        SetContentView(Resource.Layout.Fragment_Gallery);


        galleryType = Intent.GetIntExtra("galleryType", 0);

        picturesinarow = Intent.GetIntExtra("picturesinarow", 1);

        recyclerLayout = Intent.GetIntExtra("recyclerLaoyut", (int)RecyclerLayout.Multiplepics);

        hasHeader = Intent.GetBooleanExtra("hasHeader", false);

        // Instantiate the photo album:
        loadPhotos = new BookOfLife.CustomRecyclerView.ReloadAdapter(this.galleryType);
        loadPhotos.LoadMoreItems(3);//(Constants.ITEMSPERPAGE);

        // Get our RecyclerView layout:
        mRecyclerView = FindViewById<RecyclerView>(Resource.Id.recyclerView);



        //............................................................
        // Layout Manager Setup:

        // Use the built-in linear layout manager:
        //mLayoutManager = new LinearLayoutManager(this);

        // Or use the built-in grid layout manager (two horizontal rows):
        mLayoutManager = new GridLayoutManager(this, this.picturesinarow, GridLayoutManager.Vertical, false);

        // Plug the layout manager into the RecyclerView:
        mRecyclerView.SetLayoutManager(mLayoutManager);

        //............................................................
        // Adapter Setup:

        // Create an adapter for the RecyclerView, and pass it the
        // data set (the photo album) to manage:
        mAdapter = new PhotoAlbumAdapter(loadPhotos, this.picturesinarow, (RecyclerLayout)this.recyclerLayout, this.hasHeader);

        // Register the item click handler (below) with the adapter:
        mAdapter.ItemClick += OnItemClick;

        // Plug the adapter into the RecyclerView:
        mRecyclerView.SetAdapter(mAdapter);
        //.........................................................................

        //Set Spanwidth for GridHeader
        mLayoutManager.SetSpanSizeLookup(new GridViewSpansizeLookup(mAdapter, mLayoutManager));


        // On Scroll Listener
        var onScrollListener = new XamarinRecyclerViewOnScrollListener(mLayoutManager);
        onScrollListener.LoadMoreEvent += (object sender, EventArgs e) => 
        {
            int oldCount = loadPhotos.pictures.Count;
            loadPhotos.LoadMoreItems(3);//(Constants.LOADNEXTITEMSTHRESHHOLD);


            mAdapter.NotifyItemRangeChanged(oldCount - 1, loadPhotos.pictures.Count);
        };

        mRecyclerView.AddOnScrollListener(onScrollListener);
    }

Hope, you guys can help me out here :)

Upvotes: 1

Views: 2152

Answers (1)

innomotion media
innomotion media

Reputation: 922

Okay I seem to have found an easy fix for this:

if (!mRecyclerView.isComputingLayout())
    mAdapter.NotifyItemRangeChanged(oldCount - 1, loadPhotos.pictures.Count);

I just need to make sure, I have always enough photos so that the recycler view would scroll.

Upvotes: 2

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