Based on your multi select and expandable list example, I'm trying to combine those two - I think I did not change anything relevant.

Showing the data with headers works fine, expanding/collapsing works fine. BUT as soon as I start deleting something, it get's messed up.

Observations

• deleting items and not collapsing anything works visually fine

Problem

• I select the first sub item and delete it, then I collapse the first header and see, the second one is missing
• I select the first two sub items and delete them, then I collapse the first header and see, the second and third header is missing

Afterwards, more problems occur (expanding a header that still exists will show selected items for example, ...)

How I set up my adapter

    mFastAdapter = new FastItemAdapter<>();
    mActionModeHelper = new ActionModeHelper(mFastAdapter, R.menu.menu_folders, new ActionBarCallBack());

    // 2) FastAdapter Setup
    mFastAdapter.withSelectable(true);
    mFastAdapter.withMultiSelect(true);
    mFastAdapter.withSelectOnLongClick(true);
    mFastAdapter.withOnPreClickListener(new FastAdapter.OnClickListener<IItem>() {
        @Override
        public boolean onClick(View v, IAdapter<IItem> adapter, IItem item, int position) {
            //we handle the default onClick behavior for the actionMode. This will return null if it didn't do anything and you can handle a normal onClick
            Boolean res = mActionModeHelper.onClick(item);
            return res != null ? res : false;
        }
    });
    mFastAdapter.withOnPreLongClickListener(new FastAdapter.OnLongClickListener<IItem>() {
        @Override
        public boolean onLongClick(View v, IAdapter<IItem> adapter, IItem item, int position) {
            ActionMode actionMode = mActionModeHelper.onLongClick(mActivity, position);

            if (actionMode != null) {
                //we want color our CAB
                mActivity.findViewById(R.id.action_mode_bar).setBackgroundColor(UIUtils.getThemeColorFromAttrOrRes(mActivity, R.attr.colorPrimary, R.color.material_drawer_primary));
            }

            //if we have no actionMode we do not consume the event
            return actionMode != null;
        }
    });

How I fill my data

    // List of sub items without headers
    List<FolderItem> folders = ...;

    // Test - group items in groups of 10
    List<IItem> items = new ArrayList<>();
    int count = folders.size();
    int headers = (int)Math.ceil((float)folders.size() / 10f);
    for (int i = 0; i < headers; i++)
    {
        FolderItemHeader header = new FolderItemHeader()
                .withHeader("Header " + (i + 1))
                .withName("Header " + (i + 1))
                .withDescription("Description...")
                .withSubItems(folders.subList(i * 10, Math.min(count, i * 10 + 10)))
                // ALL folder items have an id that represents the rowid in the database, so
                // the ids are > 0 AND unique for sure!
                // using ids < 0 will result in no confilcting ids for sure
                .withIdentifier(-1 - i)
                .withIsExpanded(true);
        items.add(header);
    }

    // set data
    FastItemAdapter<IItem> fastAdapter = (FastItemAdapter<IItem>)mBinding.rvData.getAdapter();
    fastAdapter.setNewList(items);

We are currently in the progress of finalising the API changes and a huge refactor for the FastAdapter.

As it is really important for us to make the library as easy to use, but also as powerful and flexible as possible, we want to hear your feedback.

You can follow the current progress here: https://github.com/mikepenz/FastAdapter/pull/443 and also use the SNAPSHOT to include it into your app, and test it out. Currently the only documentation for V3 is the commit changelog + the sample application.

Please check it out, and give us suggestions, review the changes, and contribute and help to make v3 the best release ever.

Please keep general discussion here, and do code reviews on the PR.

OVERVIEW

• Adapter wrapping was removed
  • FastAdapter.with() is the new way to go
• HeaderAdapter, FooterAdapter were removed, just use multiple ItemAdapters instead
• Extension support
  • Selection (currently still in the core lib) and Expandable's are no longer a core functionality, but instead use the Extension interface, to add their functionality to the library
• GenericItemAdapter's will be removed and replaced in favour of the new ModelAdapter
• The ItemAdapter is now based on the ModelAdapter (this sadly required a second generic type to be defined)
• ...

Hello, I'm using Realm as my local backend and I would like to use the FastAdapter to populate my (many) RecyclerViews, however my realm models are separated from the ui part in its own project and each of the objects could be used on several views, so to extend my models as in the RealmExample is not an option.

Also I would like to be able to sort my adapters, and group them (providing a group header). I've reading the documentation and the examples and I'm a bit confused about what adapter to use and where, and how to add a "headeritem". The following is what I have made so far:

I have a Realm class like the following (I will omit the get and sets for the realm part)

public class Contender extends RealmObject  {

    @PrimaryKey
    private String UUID;
    private String name;
    private int total;
    private Competition competition;

}

Where Competition is another RealmObject:

public class Competition extends RealmObject  {

    @PrimaryKey
    private String UUID;
    private String name;
}

In order to populate a FastAdapter I have created a ContenderItem like this:

public class ContenderItem  extends GenericAbstractItem<Contender, ContenderItem, ContenderItem.ViewHolder>
{

    //the static ViewHolderFactory which will be used to generate the ViewHolder for this Item
    private static final ViewHolderFactory<? extends ViewHolder> FACTORY = new ItemFactory();

    public ContenderItem(Contender contender) {
        super(contender);       
    }

    public int getTotal()
    {
        return getModel().getTotal();
    }

    public String getTotalString()
    {
        return String.valueOf(getTotal());
    }

    public String getCompetitionDescription()
    {
        return getModel().getCompetition().getName();
    }


    @Override
    public int getType() {
        return R.id.fastadapter_generic_icon_item_id;
    }

    @Override
    public int getLayoutRes() {
        return R.layout.list_contender_item;
    }

    @Override
    public void bindView(ViewHolder holder) {
        super.bindView(holder);   
        holder.title.setText(getModel().getName());
        holder.subtitle.setText(getCompetitionDescription());
    }

    /**
     * our ItemFactory implementation which creates the ViewHolder for our adapter.
     * It is highly recommended to implement a ViewHolderFactory as it is 0-1ms faster for ViewHolder creation,
     * and it is also many many times more efficient if you define custom listeners on views within your item.
     */
    protected static class ItemFactory implements ViewHolderFactory<ViewHolder> {
        public ViewHolder create(View v) {
            return new ViewHolder(v);
        }
    }

    /**
     * return our ViewHolderFactory implementation here
     *
     * @return
     */
    @Override
    public ViewHolderFactory<? extends ViewHolder> getFactory() {
        return FACTORY;
    }


     * A simple Comparator to sort the items ascending.
     */
    public static class TotalComparatorAscending implements Comparator<ContenderItem>, Serializable {
        @Override
        public int compare(ContenderItem lhs, ContenderItem rhs) {
            if (lhs.getCompetitionDescription().equals(rhs.getCompetitionDescription()))
                return Integer.valueOf(lhs.getTotal()).compareTo(rhs.getTotal());
            return  lhs.getCompetitionDescription().compareTo(rhs.getCompetitionDescription());
        }
    }

    /**
     * A simple Comparator to sort the items ascending.
     */
    public static class TotalComparatorDescending implements Comparator<ContenderItem>, Serializable {
        @Override
        public int compare(ContenderItem lhs, ContenderItem rhs) {
            if (lhs.getCompetitionDescription().equals(rhs.getCompetitionDescription()))
                return -Integer.valueOf(lhs.getTotal()).compareTo(rhs.getTotal());
            return  -lhs.getCompetitionDescription().compareTo(rhs.getCompetitionDescription());
        }
    }


    /**
     * our ViewHolder
     */
    protected static class ViewHolder extends RecyclerView.ViewHolder {
        protected View view;

        @BindView(R.id.title_textview)
        AppCompatTextView title;

        @BindView(R.id.subtitle_textview)
        AppCompatTextView subtitle;

        public ViewHolder(View view) {
            super(view);
            ButterKnife.bind(this, view);
            this.view = view;
        }
    }
}

I have a RecyclerView that is populated on the onViewCreated method of the Fragment that holds it:

  private FastAdapter fastAdapter;
 @Override
   public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
            //create our FastAdapter which will manage everything
        fastAdapter = new FastAdapter();
        GenericItemAdapter<Contender, ContenderItem> itemAdapter = new GenericItemAdapter<>(ContenderItem::new);
        RecyclerView.Adapter adapter = itemAdapter.wrap(fastAdapter);

       RealmResults<Contender> contenderList = realm.where(Contender.class).findAll();
       itemAdapter.addModel(contenderList);

}

This code is working ok and although I'm not so sure about if I should use the GenericItemAdapter or another adapter, it is very straightforward.

Now I want to group all contenders by competitions, an add add a "Header / section item" with the competition name, and here is where I'm stuck.

I started by creating a "SectionItem" very similar to the ContenderItem:

public class SectionItem extends AbstractItem<SectionItem, SectionItem.ViewHolder> {


    //the static ViewHolderFactory which will be used to generate the ViewHolder for this Item
    private static final ViewHolderFactory<? extends ViewHolder> FACTORY = new ItemFactory();

    private String title = "";

    @Override
    public int getType() {
        return 0;
    }

    @Override
    public int getLayoutRes() {
        return R.layout.list_section_header;
    }

    public SectionItem withTitle(String title)
    {
        this.title = title;
        return this;
    }

    @Override
    public void bindView(ViewHolder holder) {
        super.bindView(holder);
        holder.title.setText(title);
    }

    /**
     * our ItemFactory implementation which creates the ViewHolder for our adapter.
     * It is highly recommended to implement a ViewHolderFactory as it is 0-1ms faster for ViewHolder creation,
     * and it is also many many times more efficient if you define custom listeners on views within your item.
     */
    protected static class ItemFactory implements ViewHolderFactory<SectionItem.ViewHolder> {
        public SectionItem.ViewHolder create(View v) {
            return new SectionItem.ViewHolder(v);
        }
    }

    /**
     * return our ViewHolderFactory implementation here
     *
     * @return
     */
    @Override
    public ViewHolderFactory<? extends SectionItem.ViewHolder> getFactory() {
        return FACTORY;
    }


    public static class ViewHolder extends RecyclerView.ViewHolder {
        protected View view;

        @BindView(R.id.section_text)
        AppCompatTextView title;

        public ViewHolder(View view) {
            super(view);
            ButterKnife.bind(this, view);
            this.view = view;
        }
    }
}

And, using streams is very easy to group the data:

        Map<Competition, List<Contender>> contendersGrouped = Stream.of(contenders).collect(Collectors.groupingBy(value -> value.getCompetition()));

But I'm stuck here, I don't know If I have to change the itemAdapter so it can use both types of items (ContenderItem and SectionItem), or I can just wrap the itemAdapter in another adapter (A HeaderAdapter), but then I don't know how to link both so they group properly.

So my questions are the following:

1. Am I using the best way to link the realm library with FastAdapter without extending the model?
2. What is the best way to create a grouped by property adapter with section items?

Thank you for your awesome work,

Gabriel

I think following SHOULD work, but it does not. Any ideas why?

public class Item
{
    @Override
    public void bindView(ViewHolder viewHolder, List payloads)
    {
        super.bindView(viewHolder, payloads);

        // place 1: here it works as expected
        ViewUtil.addTouchResize(viewHolder.itemView);
    }

    @Override
    public void unbindView(ViewHolder viewHolder)
    {
        super.unbindView(viewHolder);
        viewHolder.reset();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder
    {
        public ViewHolder(View view)
        {
            super(view);
            // place 2: here it does NOT work
            ViewUtil.addTouchResize(view);
        }
        
        public void reset()
        {
            ViewUtil.clearAnimation(itemView);
        }
    }
}

My ViewUtil calls view.setOnTouchListener(...) in addTouchResize and restores all views settings and cancels all animations in clearAnimation.

I should set the onTouchListener only when I create the ViewHolder not everytime it gets bound. Any ideas why this is not working in the ViewHolders constructor?

Hi! When I copy and paste SampleItem class Android Studio returns me this error: I've only changed name of the class.

package com.franci22.supersecureencryption.items;

import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;

import com.franci22.supersecureencryption.R;
import com.mikepenz.fastadapter.items.AbstractItem;

import java.util.List;

public class ListItem extends AbstractItem<ListItem, ListItem.ViewHolder> {

    public String name;
    public String description;

    //The unique ID for this type of item
    @Override
    public int getType() {
        return R.id.list_item_id;
    }

    //The layout to be used for this type of item
    @Override
    public int getLayoutRes() {
        return R.layout.list_item;
    }

    //The logic to bind your data to the view
    @Override
    public void bindView(ViewHolder viewHolder, List<Object> payloads) {
        //call super so the selection is already handled for you
        super.bindView(viewHolder, payloads);

        //bind our data
        //set the text for the name
        viewHolder.name.setText(name);
        //set the text for the description or hide
        viewHolder.description.setText(description);
    }

    //reset the view here (this is an optional method, but recommended)
    @Override
    public void unbindView(ViewHolder holder) {
        super.unbindView(holder);
        holder.name.setText(null);
        holder.description.setText(null);
    }

    //The viewHolder used for this item. This viewHolder is always reused by the RecyclerView so scrolling is blazing fast
    protected static class ViewHolder extends RecyclerView.ViewHolder {
        protected TextView name;
        protected TextView description;

        public ViewHolder(View view) {
            super(view);
            this.name = (TextView) view.findViewById(R.id.material_drawer_name);
            this.description = (TextView) view.findViewById(R.id.material_drawer_description);
        }
    }
}

Why? Thanks!

I am currently trying and testing a NEW behavior of the FastAdapter which will allow more flexibility for developers.

All changes are done in this branch: https://github.com/mikepenz/FastAdapter/commits/feature/alternativeStateManagement

And a first demo application is also available: https://drive.google.com/open?id=0B4Y8HN2BnSjpdG04MGk0cnMySmc

I would be happy If people could test this new behavior and report back.

You can also test the whole thing in your app via this SNAPSHOT (available on the SNAPSHOT maven repo):

compile('com.mikepenz:fastadapter:1.5.0.b2-SNAPSHOT@aar') {
    transitive = true
}

//extension:
compile 'com.mikepenz:fastadapter-extensions:1.5.0.b2-SNAPSHOT@aar'
//The tiny Materialize library used for its useful helper classes
compile 'com.mikepenz:materialize:0.8.8@aar'

Details

• [ ] Used library version 3.2.5
• [ ] Used support library version 27.1.1
• [ ] Used gradle build tools version 3.1.3
• [ ] Used tooling / Android Studio version 3.1.3

About this issue

i am not sure if this is a bug in the library or somewhere else or if im somehow missing something... the issue is that some views do not seem to be binded/unbinded properly and i am getting duplicate images. here is an example:

as you can see, "Madam Secretary" and "Nashville" have the same image. this seems to be happening at random - if i scroll up and down a few times, this would happen to different items.

things to note (in case they matter):

• i am using kotlin
• i am using ModelAdapter
• the adapter is filtered while this is happening

here are my bindView and unbindView:

override fun bindView(holder: ViewHolder, payloads: MutableList<Any>)
    {
        super.bindView(holder, payloads)

        val view = holder.view
        val context = view.context

        Picasso.with(context)
            .load(model._imageUrl)
            .placeholder(R.drawable.image_loading)
            .error(R.drawable.image_error)
            .fit()
            .centerInside()
            .into(view.iv_showImage)

        (view as FrameLayout).foreground =
                FastAdapterUIUtils.getSelectablePressedBackground(context,
                                                                  context.resources.getColor(R.color.colorPrimaryTransparent),
                                                                  255,
                                                                  true)
        val nameAndYear = "${model._name}\n(${model._year})"
        view.tv_nameAndYear.text = nameAndYear

        if (model.isRunning())
            view.tv_status.visibility = View.GONE
        else
            view.tv_status.apply {
                visibility = View.VISIBLE
                setText(R.string.showEnded)
            }
    }

override fun unbindView(holder: ViewHolder)
    {
        super.unbindView(holder)

        holder.view.apply {
            tv_status.text = ""
            tv_nameAndYear.text = ""
            iv_showImage.setImageDrawable(null)
        }
    }

Things i have tried (inside unbindView method)

i found a few suggested solutions on StackOverflow but none of them work for me

• imageView.setImageDrawable(null)
• imageView.setImageBitmap(null)
• imageView.setImageResource(0)
• imageView.setImageResource(android.R.color.transparent)

up until today imageView.setImageDrawable(null)has been working just fine but not anymore for some reason... is my code wrong somehow? is anybody else experiencing this issue?

Hi there, i have just migrated my large project to Fast Adapter 4 (Kotlin). It costs me about 2 days with 6 hours work each day because i use this lib in first place to my app and it's little difficult to find some good examples when using this lib from Kotlin project too.

I just wanted to say that for the moment everything seems to be working OK (Comparator, Filter, Listeners, ItemAdapter etc.)

Hi everyone, I was follow the all API step by step using fastadapter. I have some problem. When I search some query and update the item, then on the list is not update (until I touch the screen).

I use search view:

            @Override
            public boolean onQueryTextSubmit(String query) {

                if(!querySearch.equals(query)){
                    querySearch = query; // the query search

                    // 1. First, clear the array of data
                    fastItemAdapter.clear();

                    // 2. Notify the adapter of the update
                    fastItemAdapter.notifyDataSetChanged();
                    // fastItemAdapter.notifyAdapterDataSetChanged();

                    // 3. Reset endless scroll listener when performing a new load
                    endlessRecyclerOnScrollListener.resetPageCount();
                }

                return true;
            }

The Layout Grid:

   GridLayoutManager gridLayoutManager = new GridLayoutManager(ChooseUserActivity.this, 3);
    gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
        @Override
        public int getSpanSize(int position) {
            switch (fastItemAdapter.getItemViewType(position)) {
                case R.id.fastadapter_progress_item_id:
                    return 3;
                case R.id.fastadapter_user_item_id:
                    return 1;
                default:
                    return -1;
            }
        }
    });

Wrapper:

   recyclerView.setAdapter(footerAdapter.wrap(fastItemAdapter));

I Dont how to fix it, because I was log the request URL and it response the data, but on the list (recyleview) somethimes not showing (until I touch or scroll the screen)

*NOTE: when I remove the footerAdapter (not using footer adapter) then it working good. But I need loading animation on footer so I use footer Adapter :'(

About this issue

Issue

When I have expandable items (each level implements IExpandable and all use auto expand) that look like following:

• Top 1
  • Sub 1.1
    • SubSub 1.1.1
    • SubSub 1.1.2
    • SubSub 1.1.3
  • Sub 1.2
• Top 2

And I click Top 1, then SubSub 1.1.2 and SubSub 1.1.3 are not removed. Seems like FastAdapter does not sum up all sub items (including nested ones) when it collapses a parents items but only direct children.

Note

I found out that isOnlyOneExpandedItem in the expandable extension only works at the lowest level (at Sub Sub level in the example above) - it would be nice to allow one expanded item at each level only as well, this was actually what I was expecting.

Details

• Used library version: 5.0.0
• android x recyclerview: 1.1.0

Setup looks like following:

fastAdapter = FastAdapter.with(itemAdapter)
            .withSavedInstanceState(savedInstanceState)

fastAdapter.getExpandableExtension().apply {
	//isOnlyOneExpandedItem = true
}

And my items look like following:

class Item(
    val data: TopData,
    val childItems: MutableList<ChildItem>
) : AbstractItem<Item.ViewHolder>(), IExpandable<Item.ViewHolder> {
	// ...
}

class SubItem(
    val data: SubData,
    val childItems: MutableList<SubSubItem>
) : AbstractItem<SubItem.ViewHolder>(), IExpandable<SubItem.ViewHolder> {
	// ...
}

class SubSubItem(
    val data: SubSubData
) : AbstractItem<SubSubItem.ViewHolder>(), IExpandable<SubSubItem.ViewHolder> {
	// ...
}

So I've been trying to understand the most frequent crashes Firebase reports for my app.

Here's a preview of a typical case, on every Android version and many phone models (302 similar crashes for 220 user in the last 24 hours) :

Fatal Exception: java.lang.IndexOutOfBoundsException: Index: 25, Size: 1
       at java.util.ArrayList.get(ArrayList.java:437)
       at com.mikepenz.fastadapter.utils.DefaultItemListImpl.get(DefaultItemListImpl.java:23)
       at com.mikepenz.fastadapter.adapters.ModelAdapter.getAdapterItem(ModelAdapter.java:168)
       at com.mikepenz.fastadapter.FastAdapter.getItem(FastAdapter.java:507)
       at com.mikepenz.fastadapter.FastAdapter.getItemViewType(FastAdapter.java:581)
       at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6186)
       at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
       at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
       at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2303)
       at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1627)
       at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
       at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:665)
       at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
       at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3851)
       at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1855)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
       at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at androidx.recyclerview.widget.RecyclerView$LayoutManager.layoutDecoratedWithMargins(RecyclerView.java:9587)
       at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1685)
       at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
       at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:665)
       at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
       at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3851)
       at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at androidx.viewpager2.widget.ViewPager2.onLayout(ViewPager2.java:527)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1855)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
       at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
       at android.view.View.layout(View.java:23753)
       at android.view.ViewGroup.layout(ViewGroup.java:7277)
       at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
       at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
       at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
       at android.view.View.layout(View.java:23753)

The calling code is classic stuff

compositeDisposable.add(Single.fromCallable(() -> FastAdapterDiffUtil.INSTANCE.calculateDiff(itemAdapter, contentItems))
                    .subscribeOn(Schedulers.computation())
                    .observeOn(AndroidSchedulers.mainThread())
                    .subscribe(diffResult -> {
                        FastAdapterDiffUtil.INSTANCE.set(itemAdapter, diffResult);
                        differEndCallback();
                    })
            );

The more I'm thinking about this, the more I've come to believe this issue could be the consequence of DefaultItemListImpl's list being used by different threads.

The following scenario is very likely in the case of my app -though I can't repro it- :

1. Initial list has 50 items
2. The list is updated by LiveData from 50 items to 1 item after a search query
3. Meanwhile, the displayed RecyclerView still tries to access item 25 (i.e. what we see in the stacktrace above)

In my opinion, this is likely to happen when the user browses his books very quickly on a slow device (where UI doesn't quite catch up with the flux of data from the DB).

My question is as follows : what would be the best approach to fix that problem ?

I'd suggest the following changes on DefaultItemListImpl :

• Use Collections.synchronizedList() on DefaultItemListImpl._items and use synchronized on every class method that manipulates the list
• Perform a simple range test on get and set to make certain we don't access stuff outside the list range

What's your take about these ? 😄

About this issue

I see the same issue like in the video here: #991 and I do use stable ids in my adapter...

What I see is following

• I start a drag
• I stop it => itemTouchDropped is called followed by itemTouchStopDrag (which seems to be intended, although it seems wrong imho)
• I update my data in itemTouchDropped => this triggers a data update and updates the adapter data which may happen during a running animation...

Problem

• itemTouchStopDrag stops the drag animation, this means the item appears at its original position again although the back animation move animation is still running
• ghost views as in the mentioned other issues video

Work around

I delay the the drop data update until the itemTouchStopDrag is called after a drop.

Here's my code:

private val dragCallback = SimpleDragCallback(object : ItemTouchCallback {

        var updatedItems: List<IDataItem>? = null

        override fun itemTouchOnMove(oldPosition: Int, newPosition: Int): Boolean {
            DragDropUtil.onMove(itemAdapter, oldPosition, newPosition)  // change position
            return true
        }

        override fun itemTouchDropped(oldPosition: Int, newPosition: Int) {
            L.d { "Dropped: $oldPosition => $newPosition" }
            if (oldPosition == newPosition) {
                // drag drop to same position starts the selection mode
                select(activity, oldPosition)
            } else {
                val items = itemAdapter.adapterItems.map { it.data }
                items.forEachIndexed { index, item ->
                    item.order = index
                }
                updatedItems = items
            }
        }

        override fun itemTouchStartDrag(viewHolder: RecyclerView.ViewHolder) {
            L.d { "Drag start..." }
        }

        override fun itemTouchStopDrag(viewHolder: RecyclerView.ViewHolder) {
            L.d { "Drag stop..." }
            updatedItems?.let {
                GlobalScope.launch(Dispatchers.IO) {
                    DataManager.update(it)
                }
            }
            updatedItems = null
        }
    }).apply {
        notifyAllDrops = true
        isDragEnabled = true
    }

Question

What's the reason to not delay the itemTouchDropped until after itemTouchStopDrag? This seems unlogical to me...

Details

• [x] Used library version 5.7.0

About this issue

Hello! I've recently started to combine a series of consecutive Fragment RecyclerViews with RecycledViewPool to bump performance up via View pooling. However, it seems like that does not work too well with the FastAdapter EventHook mechanism (onPostCreateViewHolder is no longer called for "pooled" Views from following Fragments, old, no-longer-valid hooks are being reused (because of tag-based attachment?)) Any ideas on how to properly manage that case?

Best regards, Illia

Details

• Used library version 5.6.0

I need an expandable multi-level list where only one of top-level items can be expanded at a time but there is no such restrictions on lower levels (multiple items can be expanded there). Built-in isOnlyOneExpandedItem can't be used for that so I've implemented an onPreClickListener where I'm checking if top-level item is getting expanded, if so I'm collapsing everything else (items expanded on lower levels will be also collapsed and this is also expected).

It works fine if clicked item is above already expanded one but in an opposite case (expanding something below already expanded one) then clicked item is not getting expanded, only the previous expanded one gets collapsed.

• How can the issue be reproduced / sample code Look at the fork: https://github.com/koral--/FastAdapter/commit/e5dd30cd5f0284e02af026b07491d0ef5409597d

Steps to reproduce:

1. launch expandable sample
2. collapse everything
3. expand Test 6 item
4. click on Test 3 item (it gets expanded and Test 6 gets collapsed - as expected)
5. click on Test 6 item (Test 3 gets collapsed but Test 6 is not getting expanded)

What I've tried so far:

1. returning true from onPreClickListener and toggling clicked item state manually
2. adding notifyDataSetChanged call

Details

• [ ] Used library version - as on current develop tip cab93daa850d8ce848aa025a5b706f423f869ada
• [ ] Used support library version - as on current develop tip cab93daa850d8ce848aa025a5b706f423f869ada
• [ ] Used gradle build tools version - as on current develop tip cab93daa850d8ce848aa025a5b706f423f869ada
• [ ] Used tooling / Android Studio version Android Studio Bumblebee | 2021.1.1 Canary 1 Build #AI-203.7717.56.2111.7361063, built on May 14, 2021 Runtime version: 11.0.10+0-b96-7281165 x86_64 VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o. macOS 11.4 GC: G1 Young Generation, G1 Old Generation Memory: 8192M Cores: 8 Registry: external.system.auto.import.disabled=true Non-Bundled Plugins: String Manipulation, com.knziha.vectorpathtweaker, org.exbin.deltahex.intellij, mobi.hsz.idea.gitignore, Dart, com.localizely.flutter-intl, org.jetbrains.kotlin, io.flutter, kotest-plugin-intellij, org.intellij.plugins.markdown
• [ ] Other used libraries, potential conflicting libraries

Checklist

• [x] Searched for similar issues
• [x] Checked out the sample application
• [x] Read the README
• [ ] Checked out the CHANGELOG
• [ ] Checked out the MIGRATION GUIDE

About this issue

When using FastAdapterDiffUtil.calculateDiff() on any thread different from Main, there is a chance of IndexOutOfBoundsException being thrown. It is reproducible on modified DiffUtilActivity from FastAdapter's sample: https://github.com/boguszpawlowski/FastAdapter/blob/diffutil_bug/app/src/main/java/com/mikepenz/fastadapter/app/DiffUtilActivity.kt Steps to reproduce:

• Open DiffUtil Screen
• Start scrolling
• After hitting a specific time window, a crash will happen:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.mikepenz.fastadapter.app, PID: 2075
    java.lang.IndexOutOfBoundsException: Index: 26, Size: 19
        at java.util.ArrayList.get(ArrayList.java:437)
        at com.mikepenz.fastadapter.utils.DefaultItemListImpl.get(DefaultItemListImpl.kt:23)
        at com.mikepenz.fastadapter.adapters.ModelAdapter.getAdapterItem(ModelAdapter.kt:168)
        at com.mikepenz.fastadapter.FastAdapter.getItem(FastAdapter.kt:507)
        at com.mikepenz.fastadapter.FastAdapter.getItemViewType(FastAdapter.kt:581)
        at androidx.recyclerview.widget.RecyclerView$Recycler.validateViewHolderForOffsetPosition(RecyclerView.java:5978)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6158)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
        at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2303)
        at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1627)
        at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1587)
        at androidx.recyclerview.widget.LinearLayoutManager.scrollBy(LinearLayoutManager.java:1391)
        at androidx.recyclerview.widget.LinearLayoutManager.scrollVerticallyBy(LinearLayoutManager.java:1128)
        at androidx.recyclerview.widget.RecyclerView.scrollStep(RecyclerView.java:1841)
        at androidx.recyclerview.widget.RecyclerView$ViewFlinger.run(RecyclerView.java:5302)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1031)
        at android.view.Choreographer.doCallbacks(Choreographer.java:854)
        at android.view.Choreographer.doFrame(Choreographer.java:785)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1016)
        at android.os.Handler.handleCallback(Handler.java:914)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:224)
        at android.app.ActivityThread.main(ActivityThread.java:7560)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)

Observations:

• Error only occurs when diff calculation is made on thread different from Main
• Error only occurs when you are interacting with a screen in the same time (e.g. scrolling) and large number of items is removed.

My conclusion: If diff calculation is happening at the same time as some changes on the screen (user interaction, change in view hierarchy), and is done concurrently, due to item list modified and read on different threads, crash can happen.

Details

• Used library version - 5.3.5
• Used support library version - N/A
• Used gradle build tools version - 4.1.2
• Used tooling / Android Studio version - Arctic Fox 2021 Canary 4
• Other used libraries, potential conflicting libraries - N/A

Checklist

• [x] Searched for similar issues
• [x] Checked out the sample application
• [x] Read the README

Similar/Connected issues: https://github.com/mikepenz/FastAdapter/issues/772 - potential solution https://github.com/mikepenz/FastAdapter/issues/959 - key difference is that I'm NOT using Objects.hash for creating id, they are 100% stable and unique.

https://developer.android.com/topic/libraries/architecture/paging/v3-overview

Not really an urgency as it is still in alpha phase, but definitely something to plan for the middle term imho.

General problem In general, if you use expandable items and filtering together, you always lose the expandable state during filtering. This is really a problem if you want to filter and suddenly the expanded item containing the item that you want to filter out is gone because it's parent is collapsed. Additionally expanding an item while the filter is active does not respect the current active filter either it seems, I see that always all children of an item are expanded regardless of the current filter.

Crash A side effect of this behaviour is following crash if you collapse/expand items after filtering your views.

If desired, I can give you an example code with a little library that I'm rewritting currently in kotlin which is not far yet but can reproduce this issue easily.

Exception

kotlin.TypeCastException: null cannot be cast to non-null type kotlin.collections.List<Item>
    at com.mikepenz.fastadapter.adapters.ItemFilter.publishResults(ItemFilter.kt:104)
    at android.widget.Filter$ResultsHandler.handleMessage(Filter.java:282)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:6986)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:494)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)

Details

• [ ] Used library version: 5.0.0