SectionedAdapter.java

package com.examples;

import java.util.ArrayList;
import java.util.List;

import android.view.View;
import android.view.ViewGroup;
import android.widget.Adapter;
import android.widget.BaseAdapter;

abstract public class SectionedAdapter extends BaseAdapter {
    abstract protected View getHeaderView(String caption, int index,
	    View convertView, ViewGroup parent);

    private final List<Section> sections = new ArrayList<Section>();
    private static int TYPE_SECTION_HEADER = 0;

    public SectionedAdapter() {
	super();
    }

    public void addSection(String caption, Adapter adapter) {
	sections.add(new Section(caption, adapter));
    }

    public Object getItem(int position) {
	for (Section section : this.sections) {
	    if (position == 0) {
		return (section);
	    }

	    int size = section.adapter.getCount() + 1;

	    if (position < size) {
		return (section.adapter.getItem(position - 1));
	    }

	    position -= size;
	}

	return (null);
    }

    public int getCount() {
	int total = 0;

	for (Section section : this.sections) {
	    total += section.adapter.getCount() + 1; // add one for header
	}

	return (total);
    }

    @Override
    public int getViewTypeCount() {
	int total = 1; // one for the header, plus those from sections

	for (Section section : this.sections) {
	    total += section.adapter.getViewTypeCount();
	}

	return (total);
    }

    @Override
    public int getItemViewType(int position) {
	int typeOffset = TYPE_SECTION_HEADER + 1; // start counting from here

	for (Section section : this.sections) {
	    if (position == 0) {
		return (TYPE_SECTION_HEADER);
	    }

	    int size = section.adapter.getCount() + 1;

	    if (position < size) {
		return (typeOffset + section.adapter
			.getItemViewType(position - 1));
	    }

	    position -= size;
	    typeOffset += section.adapter.getViewTypeCount();
	}

	return (-1);
    }

    public boolean areAllItemsSelectable() {
	return (false);
    }

    @Override
    public boolean isEnabled(int position) {
	return (getItemViewType(position) != TYPE_SECTION_HEADER);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
	int sectionIndex = 0;

	for (Section section : this.sections) {
	    if (position == 0) {
		return (getHeaderView(section.caption, sectionIndex,
			convertView, parent));
	    }

	    int size = section.adapter.getCount() + 1;

	    if (position < size) {
		return (section.adapter.getView(position - 1, convertView,
			parent));
	    }

	    position -= size;
	    sectionIndex++;
	}

	return (null);
    }

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

    class Section {
	String caption;
	Adapter adapter;

	Section(String caption, Adapter adapter) {
	    this.caption = caption;
	    this.adapter = adapter;
	}
    }
}