Divide Elements on Groups in Recyclerview or Grouping Recyclerview Items ,Say by Date

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Divide elements on groups in RecyclerView or Grouping Recyclerview items ,say by date

Here is a solution i came by with the aid of alot research over the net and this blog link as well Kartikey Kuswhaha so its not all my credit but i just want to give more clarity to it.
below is the code:
create the following files:PojoOfJsonArray,MainActivity, ListItem ,GeneralItem ,DateItem , Adapter

PojoOfJsonArray.java -this file wil represent your POJO class or whatever pojo you got going on in your app so:

 public class PojoOfJsonArray  {

    public PojoOfJsonArray(String name, String date) {
        this.name = name;
        this.date = date;
    }

    private String name,date;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }
}

MainActivity.java this is the activity that you will use to implement you recyclerview :

public class MainActivity extends AppCompatActivity {
    private List<PojoOfJsonArray> myOptions = new ArrayList<>();
    List<ListItem> consolidatedList = new ArrayList<>();

    private RecyclerView mRecyclerView;
    private Adapter adapter;

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

        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview);
        mRecyclerView.setHasFixedSize(true);

        myOptions.add(new PojoOfJsonArray("name 1", "2016-06-21"));
        myOptions.add(new PojoOfJsonArray("name 2", "2016-06-05"));
        myOptions.add(new PojoOfJsonArray("name 2", "2016-06-05"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));
        myOptions.add(new PojoOfJsonArray("name 2", "2016-06-05"));
        myOptions.add(new PojoOfJsonArray("name 3", "2016-05-17"));

        HashMap<String, List<PojoOfJsonArray>> groupedHashMap = groupDataIntoHashMap(myOptions);

        for (String date : groupedHashMap.keySet()) {
            DateItem dateItem = new DateItem();
            dateItem.setDate(date);
            consolidatedList.add(dateItem);

            for (PojoOfJsonArray pojoOfJsonArray : groupedHashMap.get(date)) {
                GeneralItem generalItem = new GeneralItem();
                generalItem.setPojoOfJsonArray(pojoOfJsonArray);//setBookingDataTabs(bookingDataTabs);
                consolidatedList.add(generalItem);
            }
        }

        adapter = new Adapter(this, consolidatedList);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        mRecyclerView.setLayoutManager(layoutManager);
        mRecyclerView.setAdapter(adapter);

    }

    private HashMap<String, List<PojoOfJsonArray>> groupDataIntoHashMap(List<PojoOfJsonArray> listOfPojosOfJsonArray) {

        HashMap<String, List<PojoOfJsonArray>> groupedHashMap = new HashMap<>();

        for (PojoOfJsonArray pojoOfJsonArray : listOfPojosOfJsonArray) {

            String hashMapKey = pojoOfJsonArray.getDate();

            if (groupedHashMap.containsKey(hashMapKey)) {
                // The key is already in the HashMap; add the pojo object
                // against the existing key.
                groupedHashMap.get(hashMapKey).add(pojoOfJsonArray);
            } else {
                // The key is not there in the HashMap; create a new key-value pair
                List<PojoOfJsonArray> list = new ArrayList<>();
                list.add(pojoOfJsonArray);
                groupedHashMap.put(hashMapKey, list);
            }
        }

        return groupedHashMap;
    }

}

the myOptions is where one would use to feed your data into.
ListItem.java 

public abstract class ListItem {

    public static final int TYPE_DATE = 0;
    public static final int TYPE_GENERAL = 1;

    abstract public int getType();
}

GeneralItem.java 

public class GeneralItem extends ListItem {
    private PojoOfJsonArray pojoOfJsonArray;

    public PojoOfJsonArray getPojoOfJsonArray() {
        return pojoOfJsonArray;
    }

    public void setPojoOfJsonArray(PojoOfJsonArray pojoOfJsonArray) {
        this.pojoOfJsonArray = pojoOfJsonArray;
    }

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

}

DateItem.java 

public class DateItem extends ListItem {

    private String date;

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

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

Adapter.java this adapter is for the recyclerview if your not well informed on how to make simple sectioned recyclerview then i suggest you read on those and be good in the area because this is abit more tricky anyways:

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

    private Context mContext;
    List<ListItem> consolidatedList = new ArrayList<>();

    public Adapter(Context context, List<ListItem> consolidatedList) {
        this.consolidatedList = consolidatedList;
        this.mContext = context;

    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,  int viewType) {

        RecyclerView.ViewHolder viewHolder = null;
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());

        switch (viewType) {

            case ListItem.TYPE_GENERAL:
                View v1 = inflater.inflate(R.layout.items, parent,
                        false);
                viewHolder = new GeneralViewHolder(v1);
                break;

            case ListItem.TYPE_DATE:
                View v2 = inflater.inflate(R.layout.itemsh, parent, false);
                viewHolder = new DateViewHolder(v2);
                break;
        }

        return viewHolder;
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder viewHolder, int position) {

        switch (viewHolder.getItemViewType()) {

            case ListItem.TYPE_GENERAL:

                GeneralItem generalItem   = (GeneralItem) consolidatedList.get(position);
                GeneralViewHolder generalViewHolder= (GeneralViewHolder) viewHolder;
                generalViewHolder.txtTitle.setText(generalItem.getPojoOfJsonArray().getName());

                break;

            case ListItem.TYPE_DATE:
                DateItem dateItem = (DateItem) consolidatedList.get(position);
                DateViewHolder dateViewHolder = (DateViewHolder) viewHolder;

                dateViewHolder.txtTitle.setText(dateItem.getDate());
                // Populate date item data here

                break;
        }
    }

    // ViewHolder for date row item
    class DateViewHolder extends RecyclerView.ViewHolder {
        protected TextView txtTitle;

        public DateViewHolder(View v) {
            super(v);
            this.txtTitle = (TextView) v.findViewById(R.id.txt);

        }
    }

    // View holder for general row item
    class GeneralViewHolder extends RecyclerView.ViewHolder {
        protected TextView txtTitle;

        public GeneralViewHolder(View v) {
            super(v);
            this.txtTitle = (TextView) v.findViewById(R.id.txt);

        }
    }

    @Override
    public int getItemViewType(int position) {
        return consolidatedList.get(position).getType();
    }

    @Override
    public int getItemCount() {
        return consolidatedList != null ? consolidatedList.size() : 0;
    }

}

and this has two layout being used . thus all

Divide elements on groups in RecyclerView

For example you can:

  1. Use a TreeMap<Date,List<Event>> for splitting elements by date. This will be a collection for keeping your business objects. Of course if you already have a similar structure you can keep it. It's just important to have something for easily building list of items for populating UI with right elements order.

  2. Define a dedicated abstract type for List items (e.g. ListItem) to wrap your business objects. Its implementation could be something like this:

    public abstract class ListItem {

        public static final int TYPE_HEADER = 0;
        public static final int TYPE_EVENT = 1;

        abstract public int getType();
    }

  3. Define a class for each of your List element type (here I added just two types but you can use many as you need):

    public class HeaderItem extends ListItem {

        private Date date;

        // here getters and setters 
        // for title and so on, built
        // using date

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

    }

    public class EventItem extends ListItem {

        private Event event;

        // here getters and setters 
        // for title and so on, built 
        // using event

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

    }

  4. Create a List as follows (where mEventsMap is map build at point 1):

    List<ListItem> mItems;
    // ...
    mItems = new ArrayList<>();
    for (Date date : mEventsMap.keySet()) {
        HeaderItem header = new HeaderItem();
        header.setDate(date); 
        mItems.add(header);
        for (Event event : mEventsMap.get(date)) {
            EventItem item = new EventItem();
            item.setEvent(event);
            mItems.add(item);
        }
    }

  5. Define an adapter for your RecyclerView, working on List defined at point 4. Here what is important is to override getItemViewType method as follows:

    @Override
    public int getItemViewType(int position) {
        return mItems.get(position).getType();
    }

    Then you need to have two layouts and ViewHolder for header and event items. Adapter methods should take care of this accordingly: 

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        if (viewType == ListItem.TYPE_HEADER) {
            View itemView = mLayoutInflater.inflate(R.layout.view_list_item_header, parent, false);
            return new HeaderViewHolder(itemView);
        } else {
            View itemView = mLayoutInflater.inflate(R.layout.view_list_item_event, parent, false);
            return new EventViewHolder(itemView);
        }
    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder viewHolder, final int position) {
        int type = getItemViewType(position);
        if (type == ListItem.TYPE_HEADER) {
            HeaderItem header = (HeaderItem) mItems.get(position);
            HeaderViewHolder holder = (HeaderViewHolder) viewHolder;
            // your logic here
        } else {            
            EventItem event = (EventItem) mItems.get(position);
            EventViewHolder holder = (EventViewHolder) viewHolder;
            // your logic here
        }
    }

Here it is a repository on GitHub providing an implementation of the approach explained above.

Grouping recycler-view items by date?

Sounds like you just want to have two ViewTypes like explained here

You might also want to take a look at this library and if you want it to be expandable and sexy you could take a look at Advanced RecyclerView library.

How to add dividers, spacers, or header with text to a recylerview

I took a bit of time but I was able to do it.

This is the output

Recycler view with draggable items and group by

1) MainActivity.java

public class MainActivity extends AppCompatActivity implements OnStartDragListener{

RecyclerView recyclerView;
private ItemTouchHelper mItemTouchHelper;
private List<Item> itemList = new ArrayList<>();
private RecyclerViewAdapter mAdapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

    mAdapter = new RecyclerViewAdapter(itemList, MainActivity.this);
    RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getApplicationContext());
    recyclerView.setLayoutManager(mLayoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.addItemDecoration(new SeparationDecorator());
    recyclerView.setAdapter(mAdapter);
    ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(mAdapter);
    mItemTouchHelper = new ItemTouchHelper(callback);
    mItemTouchHelper.attachToRecyclerView(recyclerView);
    prepareItemData();
}

private void prepareItemData() {
    Item item = new Item("Apple Pay");
    itemList.add(item);
    item = new Item("1706-XXXX-XXXX-1112");
    itemList.add(item);
    item = new Item("Google pay");
    itemList.add(item);
    mAdapter.notifyDataSetChanged();
}

@Override
public void onStartDrag(RecyclerView.ViewHolder viewHolder) {
    mItemTouchHelper.startDrag(viewHolder);
}
}

2) OnStartDragListener.java

public interface OnStartDragListener {
   void onStartDrag(RecyclerView.ViewHolder viewHolder);
}

3) SimpleItemTouchHelperCallback.java

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback {

private final ItemTouchHelperAdapter mAdapter;

public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter adapter) {
    mAdapter = adapter;
}

@Override
public boolean isLongPressDragEnabled() {
    return true;
}

@Override
public boolean isItemViewSwipeEnabled() {
    return false; // make this true to enable swipe to delete
}

@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
    int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
    int swipeFlags = ItemTouchHelper.START | ItemTouchHelper.END;
    return makeMovementFlags(dragFlags, swipeFlags);
}

@Override
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
                      RecyclerView.ViewHolder target) {
    mAdapter.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
    return true;
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
    mAdapter.onItemDismiss(viewHolder.getAdapterPosition());
}

}

4) ItemTouchHelperAdapter.java

public interface ItemTouchHelperAdapter {
    void onItemMove(int fromPosition, int toPosition);
    void onItemDismiss(int position);
}

5) SeparationDecorator.java

public class SeparationDecorator extends RecyclerView.ItemDecoration {
private int textSize = 50;
private int groupSpacing = 100;

private Paint paint = new Paint();
{
    paint.setTextSize(textSize);
}

@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
    for (int i = 0; i < parent.getChildCount(); i++) {
        View view = parent.getChildAt(i);
        int position = parent.getChildAdapterPosition(view);
        if (position == 0) {
            c.drawText("DEFAULT", view.getLeft(),
                    view.getTop() - groupSpacing / 2 + textSize / 3, paint);
        } else if(position == 1) {
            c.drawText("OTHER", view.getLeft(),
                    view.getTop() - groupSpacing / 2 + textSize / 3, paint);
        }
    }
}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    if (parent.getChildAdapterPosition(view) == 0 || parent.getChildAdapterPosition(view) == 1) {
        outRect.set(0, groupSpacing, 0, 0);
    }
}
}

6) RecyclerViewAdapter.java

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> implements ItemTouchHelperAdapter{

private List<Item> itemList;
private Context context;

@Override
public void onItemMove(int fromPosition, int toPosition) {
    Item prev = itemList.remove(fromPosition);
    itemList.add(toPosition > fromPosition ? toPosition - 1 : toPosition, prev);
    notifyItemMoved(fromPosition, toPosition);
}

@Override
public void onItemDismiss(int position) {
    itemList.remove(position);
    notifyItemRemoved(position);
}

public class MyViewHolder extends RecyclerView.ViewHolder {
    public TextView title;

    public MyViewHolder(View view) {
        super(view);
        title = (TextView) view.findViewById(R.id.title);
    }
}

public RecyclerViewAdapter(List<Item> itemList, Context context) {
    this.itemList = itemList;
    this.context = context;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.view_item, parent, false);

    return new MyViewHolder(itemView);
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
    Item movie = itemList.get(position);
    holder.title.setText(movie.getTitle());
}

@Override
public int getItemCount() {
    return itemList.size();
}
}

7) Item.java

public class Item {
private String title;

public Item(String title) {
    this.title  = title;
}

public void setTitle(String title) {
    this.title = title;
}

public String getTitle() {
    return title;
}
}

This is it. This was able to solve your problem.

I am not able to explain you the complete code, I will take some time in future definitely and explain it.

Not able to parse JSON into a recyclerview

You are getting data in an asynchronous way but you are setting data in recyclerview as a synchronous way that's why the list is empty. Follow the given strategy:

Replace adapter.notifyDataSetChanged() to update() method and remove all code after parseJSON(); method.

private void update(){ 

    HashMap<String, List<StreamItem>> groupedHashMap = groupDataIntoHashMap(myOptions);

            for (String date : groupedHashMap.keySet()) {
                HeaderItem dateItem = new HeaderItem();
                dateItem.setDate(date);
                consolidatedList.add(dateItem);

                for (StreamItem pojoOfJsonArray : groupedHashMap.get(date)) {
                    EventItem generalItem = new EventItem();
                    generalItem.setStreamItem(pojoOfJsonArray);//setBookingDataTabs(bookingDataTabs);
                    consolidatedList.add(generalItem);
                }
            }

            adapter = new StreamArrayAdapter(this, consolidatedList);
            LinearLayoutManager layoutManager = new LinearLayoutManager(this);
            layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
            mRecyclerView.setLayoutManager(layoutManager);
            mRecyclerView.setAdapter(adapter);}

How to split Recycler view into 2 divisions based on type from a JSON file in Kotlin - android studio

I ended up filtering through my json file and splitting it into 2 lists. One that contains all the card types, another for all the bank types. Then passing each through their individual recycler.

val cardData: MutableList <Data> = mutableListOf<Data>()
        val bankData: MutableList <Data> = mutableListOf<Data>()

        for(i in data) {
            if (i.account_type.equals("card")){
                cardData.add(i)
        }
    }

        for(i in data) {
            if (i.account_type.equals("bank")){
                bankData.add(i)
            }
        }

To clarify, data is a list that uses the helper class Data using Gson, assign the json file to it in my main activity.


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