ultrasonic-app-subsonic-android/src/com/thejoshwa/ultrasonic/androidapp/view/GenreAdapter.java

/*
 This file is part of Subsonic.

 Subsonic is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.

 Subsonic is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with Subsonic.  If not, see <http://www.gnu.org/licenses/>.

 Copyright 2010 (C) Sindre Mehus
 */
package com.thejoshwa.ultrasonic.androidapp.view;

import com.thejoshwa.ultrasonic.androidapp.domain.Genre;
import com.thejoshwa.ultrasonic.androidapp.R;
import android.widget.ArrayAdapter;
import android.widget.SectionIndexer;
import android.content.Context;

import java.util.List;
import java.util.Set;
import java.util.LinkedHashSet;
import java.util.ArrayList;

/**
 * @author Sindre Mehus
*/
public class GenreAdapter extends ArrayAdapter<Genre> implements SectionIndexer {

    // Both arrays are indexed by section ID.
    private final Object[] sections;
    private final Integer[] positions;

    public GenreAdapter(Context context, List<Genre> genres) {
        super(context, R.layout.artist_list_item, genres);

        Set<String> sectionSet = new LinkedHashSet<String>(30);
        List<Integer> positionList = new ArrayList<Integer>(30);
        
        for (int i = 0; i < genres.size(); i++) {
            Genre genre = genres.get(i);
            String index = genre.getIndex();
            if (!sectionSet.contains(index)) {
                sectionSet.add(index);
                positionList.add(i);
            }
        }
        
        sections = sectionSet.toArray(new Object[sectionSet.size()]);
        positions = positionList.toArray(new Integer[positionList.size()]);
    }

    @Override
    public Object[] getSections() {
        return sections;
    }

    @Override
    public int getPositionForSection(int section) {
        return positions[section];
    }

    @Override
    public int getSectionForPosition(int pos) {
        for (int i = 0; i < sections.length - 1; i++) {
            if (pos < positions[i + 1]) {
                return i;
            }
        }
        return sections.length - 1;
    }
}