Question

This is XML

<?xml version="1.0" encoding="UTF-8"?>
<person>  
  <fullname>Guilherme</fullname>
  <age>10</age>
  <address>address,address,address,address,</address>
</person>

<person>  
  <fullname>Guilherme</fullname>
  <age>10</age>
  <address>address,address,address,address,</address>
</person>  

This is POJO,

public class Person {

    private String name;
    private int age;
    private String address;

    public Person(String name) {
        this.name = name;
    }

    public Person(String name, int age, String address) {
        this.name = name;
        this.age = age;
        this.address = address;
    }

    public Person() {
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

This is unmarshaller logic:

@Override
    public Object unmarshal(HierarchicalStreamReader reader,
            UnmarshallingContext context) {
        List<Person> persons = new ArrayList<Person>();
        while (reader.hasMoreChildren()) {

            Person person = new Person();
            reader.moveDown();
            System.out.println("+" + reader.getValue());
            person.setName(reader.getValue());
            reader.moveUp();
            reader.moveDown();
            System.out.println("+" + reader.getValue());
            person.setAge(Integer.parseInt(reader.getValue()));
            reader.moveUp();
            reader.moveDown();
            System.out.println("+" + reader.getValue());
            person.setAddress(reader.getValue());
            reader.moveUp();
            persons.add(person);
        }
        return persons;
    }  

I am getting following exception :

[Fatal Error] :8:2: The markup in the document following the root element must be well-formed.
Exception in thread "main" com.thoughtworks.xstream.io.StreamException:  : The markup in the document following the root element must be well-formed.
        at com.thoughtworks.xstream.io.xml.DomDriver.createReader(DomDriver.java:86)
        at com.thoughtworks.xstream.io.xml.DomDriver.createReader(DomDriver.java:70)
        at com.thoughtworks.xstream.XStream.fromXML(XStream.java:861)
        at com.mycompany.xstreamconvertersample.App.main(App.java:34)
Caused by: org.xml.sax.SAXParseException: The markup in the document following the root element must be well-formed.
        at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:239)
        at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283)
        at com.thoughtworks.xstream.io.xml.DomDriver.createReader(DomDriver.java:79)
        ... 3 more
------------------------------------------------------------------------
[ERROR]BUILD ERROR

Answer 1

The XML file is not well-formed. It cannot have two separate root elements, in your case <person>. There must be a single top-level element, such as <persons>, around both person elements.

EDIT:
In order to be well-formed, it would need to look like this

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