Images.Mediaの有効なbucket一覧を取得する

gistfile1.java

        Uri uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        Cursor c = managedQuery(uri, null, null, null, null);
        buckets.clear();
        c.moveToFirst();
        for (int i = 0; i < c.getCount(); i++) {
            String bucket_id = c
                    .getString(c.getColumnIndexOrThrow("bucket_id"));
            String bucket_name = c.getString(c
                    .getColumnIndexOrThrow("bucket_display_name"));
            buckets.put(bucket_id, bucket_name);

            c.moveToNext();
        }