JAXB: How to marshal objects in lists?

Question

Perhaps a stupid question: I have a List of type <Data> which I want to marshal into a XML file. This is my class Database containing an ArrayList...

@XmlRootElement public class Database {     List<Data> records = new ArrayList<Data>();      public List<Data> getRecords()                   { return records; }     public void       setRecords(List<Data> records) { this.records = records; } } 

...and this is class Data:

// @XmlRootElement public class Data  {     String name;     String address;      public String getName()            { return name;      }     public void   setName(String name) { this.name = name; }      public String getAddress()               { return address;         }     public void   setAddress(String address) { this.address = address; } } 

Using the following test class...

public class Test {     public static void main(String args[]) throws Exception     {         Data data1 = new Data();              data1.setName("Peter");              data1.setAddress("Cologne");          Data data2 = new Data();              data2.setName("Mary");              data2.setAddress("Hamburg");          Database database = new Database();                  database.getRecords().add(data1);                  database.getRecords().add(data2);          JAXBContext context = JAXBContext.newInstance(Database.class);         Marshaller marshaller = context.createMarshaller();                    marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);                    marshaller.marshal(database, new FileWriter("test.xml"));            } } 

...I got the result:

<database>     <records>         <address>Cologne</address>         <name>Peter</name>     </records>     <records>         <address>Hamburg</address>         <name>Mary</name>     </records> </database> 

But that's not what I was expecting, i.e. all tags for <Data> objects are missing. I am looking for a way to export the data in the following structure, but I don't know how to achieve this:

<database>     <records>         <data>             <address>Cologne</address>             <name>Peter</name>         </data>         <data>             <address>Hamburg</address>             <name>Mary</name>         </data>     </records> </database> 

---

One additional question: if I want to deal with the problem without using @XmlElementWrapper and @XmlElement annotations, I can introduce an intermediary class

public class Records {     List<Data> data = new ArrayList<Data>();      public List<Data> getData()                { return data; }     public void       setData(List<Data> data) { this.data = data; } } 

used by the modified base class

@XmlRootElement public class Database {     Records records = new Records();      public Records getRecords()                { return records; }     public void    setRecords(Records records) { this.records = records; } } 

in a slightly modified Test class:

... Database database = new Database(); database.getRecords().getData().add(data1); database.getRecords().getData().add(data2); ... 

The result also is:

<database>     <records>         <data>             <address>Cologne</address>             <name>Peter</name>         </data>         <data>             <address>Hamburg</address>             <name>Mary</name>         </data>     </records> </database> 

Is this the recommended way to create a Java class structure according to the XML file structure above?

Answer 1

On the records property add:

@XmlElementWrapper(name="records") @XmlElement(name="data") 

For more information on JAXB and collection properties see:

• JAXB & Collection Properties