When we write a XML in android, you can choose difference ways, in this case we recommend XMLSerializer, which is an efficient and maintainable way to parse XML on Android.

Implements an XML serializer supporting both DOM and SAX pretty serializing.

We put this simple line:

            xmlSerializer.setOutput(writer);
            xmlSerializer.startDocument("UTF-8", true);
            xmlSerializer.startTag(null, "doc");

            xmlSerializer.startTag(ns, country);
            xmlSerializer.text(filmObject.getCountry());
            xmlSerializer.endTag(ns, country);

            xmlSerializer.endTag(ns, "doc");
            xmlSerializer.endDocument();
            xmlSerializer.flush();

We made a example with films:

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<doc>
    <film title="Scarface">
        <runningTime>163 min.</runningTime>
        <country>USA</country>
        <director>Brian De Palma</director>
        <cast><name>Al</name>
            <surname>Pacino</surname><name> Steven</name>
            <surname>Bauer</surname><name>Michelle</name><surname>Pfeiffer</surname>
            <name>Mary Elizabeth</name>
            <surname>Mastrantonio</surname>
        </cast>
    </film>
    <film title="Hitman">
        <runningTime>96 min.</runningTime>
        <country>USA</country>
        <director>Aleksander Bach</director>
        <cast><name>Rupert</name>
            <surname>Friend</surname>
            <name>Zachary</name>
            <surname>Quinto</surname>
            <name>Hannah</name>
            <surname>Ware</surname>
            <name>Ciarán</name>
            <surname>Hinds</surname>
        </cast>
    </film>
    <film title="Out of Africa">
        <runningTime>160 min.</runningTime>
        <country>USA</country>
        <director>Sydney Pollack</director>
        <cast>
            <name>Robert</name>
            <surname>Redford</surname>
            <name>Meryl</name>
            <surname>Streep</surname>
            <name>Klaus Maria</name>
            <surname>Brandauer</surname>
            <name>Michael</name>
            <surname>Kitchen</surname>
        </cast>
    </film>
</doc>

In your activity you can put this lines with this films:

public void writeXml(List<Film> films) {


        try {
            FileOutputStream fileOutputStream = new FileOutputStream(mFileOutPut);
            XmlSerializer xmlSerializer = Xml.newSerializer();
            StringWriter writer = new StringWriter();

            xmlSerializer.setOutput(writer);
            xmlSerializer.startDocument("UTF-8", true);
            xmlSerializer.startTag(null, "doc");

            insertFilms(xmlSerializer, films);

            xmlSerializer.endTag(ns, "doc");
            xmlSerializer.endDocument();
            xmlSerializer.flush();
            String dataWrite = writer.toString();
            fileOutputStream.write(dataWrite.getBytes());
            fileOutputStream.close();

        } catch (FileNotFoundException e) {
            e.printStackTrace();

        } catch (IllegalArgumentException e) {
            e.printStackTrace();

        } catch (IllegalStateException e) {
            e.printStackTrace();

        } catch (IOException e) {
            e.printStackTrace();

        }


    }

    public void insertFilms(XmlSerializer xmlSerializer, List<Film> films) throws IOException {
        final String film = "film";
        String title = "title";
        String runningTime = "runningTime";
        String country = "country";
        String director = "director";
        String cast = "cast";
        Film filmObject;
        for (int i=0; i<films.size(); i++) {
            filmObject = films.get(i);
            xmlSerializer.startTag(ns, film);
            xmlSerializer.attribute(ns, title, filmObject.getTitle());

            xmlSerializer.startTag(ns, runningTime);
            xmlSerializer.text(filmObject.getRunningTime());
            xmlSerializer.endTag(ns, runningTime);

            xmlSerializer.startTag(ns, country);
            xmlSerializer.text(filmObject.getCountry());
            xmlSerializer.endTag(ns, country);

            xmlSerializer.startTag(ns, director);
            xmlSerializer.text(filmObject.getDirector());
            xmlSerializer.endTag(ns, director);

            xmlSerializer.startTag(ns, cast);
            insertCast(xmlSerializer, filmObject.getCast());
            xmlSerializer.endTag(ns, cast);

            xmlSerializer.endTag(null, film);
        }

    }

    public void insertCast (XmlSerializer xmlSerializer, List<Actor> cast) throws IOException {
        String name = "name";
        String surname = "surname";
        Actor actor;
        for (int i=0; i<cast.size(); i++) {
            actor = cast.get(i);
            xmlSerializer.startTag(null, name);
            xmlSerializer.text(actor.getName());
            xmlSerializer.endTag(null, name);

            xmlSerializer.startTag(null, surname);
            xmlSerializer.text(actor.getSurname());
            xmlSerializer.endTag(null, surname);
        }

    }

Example in GitHub