Alphabetindexer with Custom Adapter Managed by Loadermanager

AlphabetIndexer with Custom Adapter managed by LoaderManager

So I finally got this to work. Here's how i did it:

I added:

ListView lv = getListView();
lv.setFastScrollEnabled(true);
lv.setScrollingCacheEnabled(true);

to the onLoadFinished() method after the new cursor was swapped in like so

public void onLoadFinished(Loader<Cursor> loader, Cursor data) { 
 // Swap the new cursor in.  (The framework will take care of closing the
 // old cursor once we return.)
 mAdapter.swapCursor(data);

 ListView lv = getListView();
 lv.setFastScrollEnabled(true);
 lv.setScrollingCacheEnabled(true);

}

consequently these three statements were removed from the onActivityCreated() method of my custom ListFragment.

Getting NullPointerException with AlphabetIndexer

You should probably post more of your code to confirm this, but I'm guessing you cursos has changed, or for some other reason cursor[columnIndex] returns null, by the time getSectionForPosition is evaluated.

According to this outstanding issue, this situation will trigger a very similar NPE to what you are experiencing

Again, the real problem is somewhere in the code that you didn't post. The Alphabetindexer is just not handling that situation all too well.

Styling the sectionIndexer

Found the answer here

You have to create a theme and apply it to an activity

Android: how to use SectionIndexer

You can try to write a custom ArrayAdapter and basically return a "section header" view in the getView(...) method for the positions where headers should appear.

You'll also have to overwrite getViewTypeCount () to return the number of new types of views (in this case 2) and getItemViewType (int position) to return the type of view for the current position.

Also, the onItemClickListener should check to see if the item you clicked on is a section header.

This is my custom array adapter:

public class ItemListAdapter extends ArrayAdapter<ModelItem>
{
    private static final int    TYPE_SECTION_HEADER = 0;
    private static final int    TYPE_LIST_ITEM  = 1;

    int mDefaultRowLayoutResID;
    Context mContext;
    LayoutInflater mInflater;
    ArrayList<ModelItem> lItems;

    public ItemListAdapter(Context context, int resource, ArrayList<ModelItem> items)
    {
        super(context, resource, items);
        mContext = context;
        mResource = resource;
        mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        lItems = items;
    }

    @Override
    public ModelItem getItem(int position)
    {
        return lItems.get(position);
    }

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

    @Override
    public int getViewTypeCount()
    {
        return 2;
    }

    @Override
    public int getItemViewType(int position)
    {
        ModelItem item = lItems.get(position);
        if (item.isHeader())
        {
            return TYPE_SECTION_HEADER;
        }
        else
        {
            return TYPE_LIST_ITEM;
        }
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        ViewHolder holder;
        ModelItem item = getItem(position);

        if (convertView == null)
        {
            if (item.isHeader())
            {
                convertView = mInflater.inflate(R.layout.row_item_section_header, null);
                holder = new ViewHolder();
                holder.title = (TextView)convertView.findViewById(R.id.list_header_title);
                holder.subtitle = null;
                convertView.setTag(holder);
            }
            else
            {
                convertView = mInflater.inflate(R.layout.row_item_default, null);
                holder = new ViewHolder();
                holder.title = (TextView)convertView.findViewById(R.id.row_item_title);
                holder.subtitle = (TextView)convertView.findViewById(R.id.row_item_subtitle);
                convertView.setTag(holder);
            }
        }
        else
        {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.title.setText(item.getTitle());
        if (holder.subtitle != null)
        {
            holder.subtitle.setText(item.getSubtitle());
        }
        return convertView;
    }

    private class ViewHolder
    {
        public TextView title;
        public TextView subtitle;
        public ImageView leftIcon;
        public View rightControl;
    }
}

This is the row_item_default.xml file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    >
    <TextView
        android:id="@+id/row_item_title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
    />
    <TextView
        android:id="@+id/row_item_subtitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/row_item_title"
    />
</RelativeLayout>

and this is the row_item_section_header.xml:

<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/list_header_title"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    style="?android:attr/listSeparatorTextViewStyle"
/>

The ModelItem class is a simple container for title, subtitle and a boolean to tell if it's a section header or not.

This is not the only way to write this adapter but I hope this helps.

AlphabetIndexer setCursor doesn't update its cache

I've solved this by calling this in sequence after I set the adapter:

listView.setFastScrollEnabled(false);
listView.setFastScrollEnabled(true);

That worked for me.

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