Simpler generic RecyclerView.Adapter and RecyclerView.ViewHolder with click listener

PFRecyclerViewAdapter.java

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by Plumillon Forge.
 */
public abstract class PFRecyclerViewAdapter<T> extends RecyclerView.Adapter<PFRecyclerViewAdapter.ViewHolder> {
    private List<T> items;
    private Context context;
    private OnViewHolderClick<T> listener;

    public interface OnViewHolderClick<T> {
        void onClick(View view, int position, T item);
    }

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        private Map<Integer, View> views;

        public ViewHolder(View view, OnViewHolderClick listener) {
            super(view);
            views = new HashMap<>();
            views.put(0, view);

            if (listener != null)
                view.setOnClickListener(this);
        }

        @Override
        public void onClick(View view) {
            if (listener != null)
                listener.onClick(view, getAdapterPosition(), getItem(getAdapterPosition()));
        }

        public void initViewList(int[] idList) {
            for (int id : idList)
                initViewById(id);
        }

        public void initViewById(int id) {
            View view = (getView() != null ? getView().findViewById(id) : null);

            if (view != null)
                views.put(id, view);
        }

        public View getView() {
            return getView(0);
        }

        public View getView(int id) {
            if (views.containsKey(id))
                return views.get(id);
            else
                initViewById(id);

            return views.get(id);
        }
    }

    protected abstract View createView(Context context, ViewGroup viewGroup, int viewType);

    protected abstract void bindView(T item, PFRecyclerViewAdapter.ViewHolder viewHolder);

    public PFRecyclerViewAdapter(Context context) {
        this(context, null);
    }

    public PFRecyclerViewAdapter(Context context, OnViewHolderClick<T> listener) {
        super();
        this.context = context;
        this.listener = listener;
        items = new ArrayList<>();
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        return new ViewHolder(createView(context, viewGroup, viewType), listener);
    }

    @Override
    public void onBindViewHolder(PFRecyclerViewAdapter.ViewHolder holder, int position) {
        bindView(getItem(position), holder);
    }

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

    public T getItem(int index) {
        return ((items != null && index < items.size()) ? items.get(index) : null);
    }

    public Context getContext() {
        return context;
    }

    public void setList(List<T> list) {
        items = list;
    }

    public List<T> getList() {
        return items;
    }

    public void setClickListener(OnViewHolderClick listener) {
        this.listener = listener;
    }

    public void addAll(List<T> list) {
        items.addAll(list);
        notifyDataSetChanged();
    }

    public void reset() {
        items.clear();
        notifyDataSetChanged();
    }
}

Tag.java

public class Tag {
    public static final String DEFAULT_COLOR = "#B3E5FC";
    public String name;
    public String type;
    public String primaryColor;
    
    public Tag(String n, String t, String p) {
        name = n;
        type = t;
        primaryColor = p;
    }
}

TagListAdapter.java

import android.content.Context;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import com.scanners.android.bao.R;
import com.scanners.android.bao.api.model.Tag;

/**
 * Created by Plumillon Forge.
 */
public class TagListAdapter extends PFRecyclerViewAdapter<Tag> {
    public TagListAdapter(Context context, OnViewHolderClick listener) {
        super(context, listener);
    }

    @Override
    protected View createView(Context context, ViewGroup viewGroup, int viewType) {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View view = inflater.inflate(R.layout.item_text_color, viewGroup, false);

        return view;
    }

    @Override
    protected void bindView(Tag item, PFRecyclerViewAdapter.ViewHolder viewHolder) {
        if (item != null) {
            TextView name = (TextView) viewHolder.getView(R.id.text_name);
            TextView type = (TextView) viewHolder.getView(R.id.text_type);
            View verticalBar = viewHolder.getView(R.id.vertical_bar);

            name.setText(item.name);
            type.setText(item.type);
            verticalBar.setBackgroundColor(item.primaryColor != null ? Color.parseColor(item.primaryColor) : Color.parseColor(Tag.DEFAULT_COLOR));
        }
    }
}

I found this very useful as a simple straight forward generic adapter.

this is very usefull, thanks alot.

How to apply this with butterknife?

@Drakot - To bind with ButterKnife, use: ButterKnife.bind(this, parentView); in the ViewHolder.

Hi, have a demo how to use it; thanks.

Where can I get an example of how this code is used, there are some examples that I can use to simplify understanding.

I look forward to your comments and thank you in advance.

For some reason the OnClickListener doesn't work. I have a renamed it to CustomAdapter and the UserAdapter is the one that I am trying to instantiate.
UserAdapter userAdapter = new UserAdapter(getContext(), new CustomAdapter.OnViewHolderClick() {
@OverRide
public void onClick(View view, int position, User item) {
// do stuff
}
});

I have written a simple generic adapter that needs no code for adapters or holder.
Take a look please : https://github.com/ashkanpower/SURAdapter

@timothycoutlakis that won't work since the bindings will be in TagListAdapter, so following the example it should be called in the createView before the view return with: ButterKnife.bind(this, view);

With some more changes one could push this to the generic Adapter but this would be the quickest way.

edit: I haven't tested but I think I'm actually mistaken. The view after recycling will display wrong results unless the binding occurs in a ViewHolder with a similar structure as a standard Adapter. I'm actually still trying to find a nice way to make use of this with ButterKnife but can't seem to.

I modified @Plumillon code and created even more generic RecyclerView.Adapter
https://gist.github.com/Sumeet21/8b52dbf3222603ff8c28457905cc9c70

Hey mate, Nice one… Actually i has done some rework on that and see what we've got..
I've made it the most dynamic generic adapter ever.
https://medium.com/@sandipsavaliya/tired-with-adapters-4240e5f45c24