A Generic RecyclerView adapter implementation that can be used everywhere with any kind of RecyclerView items

GenericRecycleAdapter.java

import android.support.v7.widget.RecyclerView;
import android.util.SparseArray;
import android.view.View;
import android.view.ViewGroup;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by Mehedi on 5/31/15.
 *
 * A Generic Adapter for RecyclerView
 */

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

    /**
     * Maps the type of item with the position of such an item
     */
    SparseArray<Integer> mViewTypeMap;
    /**
     * Stores the items
     */
    List<RecyclableViewItem> mDataStore;

    protected onItemClickListener mItemClickListener;

    /**
     *
     * @param data list of items
     */
    public GenericRecycleAdapter(List<RecyclableViewItem> data){
        super();

        mDataStore = data;
        generateViewTypeMapping();
    }

    /**
     *
     * @param data list of items
     * @param itemClickListener listener for item click events
     */
    public GenericRecycleAdapter(List<RecyclableViewItem> data, onItemClickListener itemClickListener)
    {
        this(data);
        mItemClickListener = itemClickListener;
    }

    /**
     * Generate the mapping for all types of item
     */
    private void generateViewTypeMapping(){
        mViewTypeMap = new SparseArray<Integer>();
        if(mDataStore != null && !mDataStore.isEmpty())
        {
            int position = 0;

            for(RecyclableViewItem item : mDataStore)
            {
                addMappingForItem(item, position);

                position++;
            }
        }
    }

    /**
     *
     * @param item list item
     * @param position position of the item
     */
    private void addMappingForItem(RecyclableViewItem item, int position)
    {
        if(mViewTypeMap.indexOfKey(item.getViewType()) < 0)
        {
            mViewTypeMap.put(item.getViewType(), position);
        }
    }

    /**
     * Add an item at the end/bottom
     * @param item
     */
    public void appendItem(RecyclableViewItem item){
        if(mDataStore == null)
        {
            mDataStore = new ArrayList<RecyclableViewItem>();
        }

        int index = mDataStore.size();
        mDataStore.add(item);

        addMappingForItem(item, index);
        notifyItemInserted(index);
    }

    /**
     * Add an item at a given position
     * @param item
     * @param position
     */
    public void addItemAtPosition(RecyclableViewItem item, int position)
    {
        if(mDataStore == null)
        {
            mDataStore = new ArrayList<RecyclableViewItem>();
        }

        mDataStore.add(position, item);
        generateViewTypeMapping();
        notifyItemInserted(position);
    }

    /**
     * Remove the item at given position
     * @param position
     * @return the item that was removed
     */
    public RecyclableViewItem removeItemAtPosition(int position)
    {
        RecyclableViewItem item = null;

        if(mDataStore != null && mDataStore.size() > position)
        {
            item = mDataStore.remove(position);
            if(mViewTypeMap.get(item.getViewType()) == position)
            {
                generateViewTypeMapping();
            }
            notifyItemRemoved(position);
        }
        return item;
    }

    /**
     * Remove an item
     * @param item
     */
    public void removeItem(RecyclableViewItem item){
        if(mDataStore != null && !mDataStore.isEmpty()){
            int position = mDataStore.indexOf(item);
            if(mDataStore.remove(item))
            {
                if(mViewTypeMap.get(item.getViewType()) == position)
                {
                    generateViewTypeMapping();
                }
                notifyItemRemoved(position);
            }
        }
    }

    /**
     * Set the given item at specified position
     * @param position
     * @param item
     */
    public void setItemAtPosition(int position, RecyclableViewItem item){
        if(mDataStore != null && !mDataStore.isEmpty())
        {
            int viewType = mDataStore.get(position).getViewType();
            mDataStore.set(position, item);
            if(mViewTypeMap.get(viewType) == position)
            {
                generateViewTypeMapping();
            }
            else {
                addMappingForItem(item, position);
            }
            notifyItemChanged(position);
        }
    }

    /**
     *
     * @param position
     * @return item at {@param position}
     */
    public RecyclableViewItem getItemAtPosition(int position)
    {
        if(mDataStore != null && !mDataStore.isEmpty() && position >=0 && position < mDataStore.size())
        {
            return mDataStore.get(position);
        }

        return null;
    }

    /**
     *
     * @param position
     * @return Unique identifier for the item at {@param position}
     */
    @Override
    public long getItemId(int position) {
        if(mDataStore != null && !mDataStore.isEmpty() && position >=0 && position < mDataStore.size())
        {
            RecyclableViewItem item = mDataStore.get(position);
            if(item instanceof Identifiable)
            {
                return ((Identifiable) item).getId();
            }
        }
        return super.getItemId(position);
    }

    /**
     * Move an item from position {@param fromPos} to position {@param toPos}
     * @param fromPos
     * @param toPos
     */
    public void moveItem(int fromPos, int toPos)
    {
        if(mDataStore != null && !mDataStore.isEmpty())
        {
            RecyclableViewItem item = mDataStore.remove(fromPos);
            mDataStore.add(toPos, item);
            if(mViewTypeMap.get(item.getViewType()) == fromPos)
            {
                mViewTypeMap.put(item.getViewType(), toPos);
            }

            notifyItemMoved(fromPos, toPos);
        }
    }

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

        int position = mViewTypeMap.get(viewType);
        if(position >= 0)
        {
            return mDataStore.get(position).onCreateViewHolder(parent, mItemClickListener);
        }
        return null;
    }

    protected int viewTypePosition(int viewType){
        return mViewTypeMap.get(viewType);
    }

    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        mDataStore.get(position).onBindViewHolder(this, holder);

        //TODO set the item click listener here
    }

    @Override
    public int getItemCount() {
        if(mDataStore != null)
        {
            return mDataStore.size();
        }
        return 0;
    }

    @Override
    public int getItemViewType(int position) {
        if(mDataStore != null && position < mDataStore.size())
        {
            return  mDataStore.get(position).getViewType();
        }
        return super.getItemViewType(position);
    }

    /**
     * interface to listen for item clicks
     */
    public interface onItemClickListener{
        void onItemClick(int position, View clickedView);
    }
}

Identifiable.java

/**
 * Created by Mehedi on 6/2/15.
 *
 * An item that is uniquely identifiable
 */
public interface Identifiable {
    /**
     *
     * @return The unique ID of this item
     */
    int getId();
}

RecyclableViewItem.java

/**
 * Created by Mehedi on 5/31/15.
 *
 * An item that is Recyclable, can be shown in a RecyclerView
 */
public interface RecyclableViewItem<T extends RecyclerView.ViewHolder> {
    /**
     *
     * @return Class of the ViewHolder
     */
    Class<T> getViewHolderClassType();

    /**
     *
     * @return Type of View
     */
    int getViewType();

    /**
     *
     * @param parent
     * @param itemClickListener
     * @return Create and return the ViewHolder
     */
    T onCreateViewHolder(ViewGroup parent, GenericRecycleAdapter.onItemClickListener itemClickListener);

    /**
     * Update the View
     * @param viewHolder
     */
    void onBindViewHolder(RecyclerView.Adapter adapter, T viewHolder);
}

RecyclerViewDivider.java

/**
 * Created by Mehedi on 6/1/15.
 *
 * Pulled from AOSP source base and modified.
 *
 * Draws a divider in between RecyclerView items
 */
public class RecyclerViewDivider extends RecyclerView.ItemDecoration {

    private static final int[] ATTRS = new int[]{
            android.R.attr.listDivider
    };

    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;

    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    private Drawable mDivider;

    private int mOrientation;

    public RecyclerViewDivider(Context context, int orientation) {
        final TypedArray a = context.obtainStyledAttributes(ATTRS);
        mDivider = a.getDrawable(0);
        a.recycle();
        setOrientation(orientation);
    }

    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == VERTICAL_LIST) {
            drawVertical(c, parent);
        } else {
            drawHorizontal(c, parent);
        }
    }

    public void drawVertical(Canvas c, RecyclerView parent) {
        final int left = parent.getPaddingLeft();
        final int right = parent.getWidth() - parent.getPaddingRight();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    public void drawHorizontal(Canvas c, RecyclerView parent) {
        final int top = parent.getPaddingTop();
        final int bottom = parent.getHeight() - parent.getPaddingBottom();

        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                    .getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }
}