Question

public class Group {
    //many other fields
    public List<Person> persons;
}

public class Person {
    public String name; ...
}

When I marhsal I want to get a bunch of Person nodes:

<person>
    <name>..</name>
</person>
<person>
    <name>..</name>
</person>

instead of this: (a persons node with person nodes as children)

<persons>
    <person>
      <name>..</name>
    </person>
    <person>
      <name>..</name>
    </person>
<persons>

How can I achieve this?

Answer 1

UPDATE

If you are referring to persons as a grouping element rather than a root element a JAXB (JSR-222) implementation does not add one by default.

Group (Without Grouping Element)

package forum13305973;

import java.util.*;
import javax.xml.bind.annotation.*;

@XmlRootElement
public class Group {
    //many other fields
    @XmlElement(name="person")
    public List<Person> persons = new ArrayList<Person>();
}

Person

package forum13305973;

public class Person {
    public String name;
}

Demo

package forum13305973;

import javax.xml.bind.*;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Group.class);

        Group group = new Group();

        Person person1 = new Person();
        person1.name = "Jane";
        group.persons.add(person1);

        Person person2 = new Person();
        person2.name = "John";
        group.persons.add(person2);

        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        marshaller.marshal(group, System.out);
    }

}

Output

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<group>
    <person>
        <name>Jane</name>
    </person>
    <person>
        <name>John</name>
    </person>
</group>

---

Group (With Grouping Element)

You need to add an @XmlElementWrapper annotation to get a grouping element

package forum13305973;

import java.util.*;

import javax.xml.bind.annotation.*;

@XmlRootElement
public class Group {
    //many other fields
    @XmlElementWrapper
    @XmlElement(name="person")
    public List<Person> persons = new ArrayList<Person>();
}

Output (With Grouping Element)

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<group>
    <persons>
        <person>
            <name>Jane</name>
        </person>
        <person>
            <name>John</name>
        </person>
    </persons>
</group>

---

ORIGINAL ANSWER

You could do the following:

    JAXBContext jc = JAXBContext.newInstance(Person.class);
    Marshaller marshaller = jc.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); // format output
    marshaller.setProperty(Marshaller.JAXB_FRAGMENT, true); // remove header

    for(Person person : group.persons) {
        marshaller.marshal(person, System.out);
    }