MessageAdapter.java

package com.nathanrjones.messenger;

import android.location.Location;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.nathanrjones.messenger.Message.MessageType;

import java.util.List;

/**
 * An adapter to display a list of Messages.
 */
public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.MessageViewHolder> {

    private List<Message> messages;

    @Override
    public MessageViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        MessageType type = MessageType.values()[viewType];
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());

        View itemView;

        switch (type) {
            case Text:
            default:
                itemView = inflater.inflate(R.layout.item_message_text, parent, false);
                return new TextMessageViewHolder(itemView);
            case Image:
                itemView = inflater.inflate(R.layout.item_message_image, parent, false);
                return new ImageMessageViewHolder(itemView);
            case Location:
                itemView = inflater.inflate(R.layout.item_message_location, parent, false);
                return new LocationMessageViewHolder(itemView);
        }
    }

    @Override
    public void onBindViewHolder(MessageViewHolder holder, int position) {
        holder.bind(position);
    }

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

    @Override
    public int getItemViewType(int position) {
        return messages.get(position).type.ordinal();
    }

    abstract class MessageViewHolder extends RecyclerView.ViewHolder {

        final TextView timestamp;
        
        public MessageViewHolder(View itemView) {
            super(itemView);
        }

        void bind(int position) {
            Message msg = messages.get(position);
            timestamp.setText(formatTimestamp(msg.timestamp);
        }
    }

    private class TextMessageViewHolder extends MessageViewHolder {

        final TextView messageText;

        public TextMessageViewHolder(View itemView) {
            super(itemView);

            messageText = (TextView) itemView.findViewById(R.id.message_text);
        }

        @Override
        void bind(int position) {
            super.bind(position);
            
            Message msg = messages.get(position);
            messageText.setText(msg.text);
        }
    }

    private class ImageMessageViewHolder extends MessageViewHolder {

        final ImageView messageImage;

        public ImageMessageViewHolder(View itemView) {
            super(itemView);
            messageImage = (ImageView) itemView.findViewById(R.id.message_image);
        }

        @Override
        void bind(int position) {
            super.bind(position);
            
            Message msg = messages.get(position);
            messageImage.setImageDrawable(msg.image);
        }
    }

    private class LocationMessageViewHolder extends MessageViewHolder {

        public LocationMessageViewHolder(View itemView) {
            super(itemView);
        }

        @Override
        void bind(int position) {
            super.bind(position);
            
            Message msg = messages.get(position);
            Location location = msg.location;
            // TODO: Load location into MapView
        }
    }
}