BaseListAdapter.java

package com.cellasoft.univrapp.adapter;

import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import com.cellasoft.univrapp.model.Item;
import com.cellasoft.univrapp.utils.ActiveList;
import com.cellasoft.univrapp.utils.Lists;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.imageaware.ImageAware;
import com.nostra13.universalimageloader.core.imageaware.ImageViewAware;

import java.lang.ref.WeakReference;
import java.util.Collection;
import java.util.List;

public abstract class BaseListAdapter<T> extends ArrayAdapter<T> {

    private static final int REFRESH_MESSAGE = 1;

    protected LayoutInflater mInflater;
    protected int resource; // store the resource layout id for 1 row
    protected List<T> items;
    protected IncomingHandler handler = new IncomingHandler(this);
    protected ImageLoader imageLoader;

    protected ActiveList.ActiveListListener<Item> activeListListener = new ActiveList.ActiveListListener<Item>() {
        @Override
        public void onAdd(Item item) {
            refresh();
        }

        @Override
        public void onInsert(final int location, final Item item) {
            refresh();
        }

        @Override
        public void onClear() {
            refresh();
        }

        @Override
        public void onAddAll(Collection<? extends Item> items) {
            refresh();
        }
    };

    public BaseListAdapter(Context context, int resource) {
        super(context, resource);
        this.resource = resource;
        this.items = Lists.newArrayList();
        this.mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        // Get singleton instance of ImageLoader
        this.imageLoader = ImageLoader.getInstance();
    }

    public BaseListAdapter(Context context, int resource, List<T> items) {
        super(context, resource, items);
        this.resource = resource;
        this.items = items;
    }

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

    @Override
    public T getItem(int position) {
        return items.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    protected abstract void populateDataForRow(ViewHolder holder, T item, int position);

    @Override
    public abstract View getView(int position, View convertView, ViewGroup parent);

    protected void imageLoader(ViewHolder holder, String imageUrl) {
        if (!holder.isSameView(imageUrl)) {
            holder.thumbnail.setTag(imageUrl);
            ImageAware imageAware = new ImageViewAware(holder.thumbnail, false);
            imageLoader.displayImage(imageUrl, imageAware);
        }
    }

    public synchronized void addItems(List<T> items) {
        if (this.items != null) {
            this.items.addAll(items);
        } else {
            this.items = Lists.newArrayList();
            this.items.addAll(items);
        }
        refresh();
    }

    public synchronized void addItemsOnTop(List<T> items) {
        if (this.items != null) {
            this.items.addAll(0, items);
            refresh();
        } else {
            addItems(items);
        }
    }

    public synchronized void refresh() {
        handler.sendEmptyMessage(REFRESH_MESSAGE);
    }

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

    public synchronized void setItems(List<T> items) {
        this.items = items;
        refresh();
    }

    @Override
    public synchronized void clear() {
        items.clear();
        refresh();
    }

    static class IncomingHandler extends Handler {
        private final WeakReference<BaseListAdapter<?>> mAdapter;

        IncomingHandler(BaseListAdapter<?> adapter) {
            this.mAdapter = new WeakReference<BaseListAdapter<?>>(adapter);
        }

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            BaseListAdapter<?> adapter = mAdapter.get();
            if (adapter != null && msg.what == REFRESH_MESSAGE) {
                adapter.notifyDataSetChanged();
            }
        }
    }

    class ViewHolder {
        int position;
        ImageView thumbnail;

        public boolean isSameView(String tag) {
            if (tag == null) {
                return thumbnail.getTag() == null;
            }
            return tag.equals(thumbnail.getTag());
        }
    }
}