JAXB syntax help

[Matthew Snow]

I need to unmarshal a tricky xml stream and I need some help. Here is an example of what I'm running into:

<pet type=dog>
	<name>Fido</name>
</pet>

A sample POJO for this xml would look like this:

@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Pet {
	@XmlAttribute
	private String type;
	public Pet() {}
	public void setType(String type) {
		this.type = type;
	}
	public String getType() {
		return type;
	}
}

The problem is how do I capture the <name> element? If I set it as an @XmlAttribute name, it comes up null. If I create a java class called Name and include it in Pet as a @XmlElement, it does get instantiated so I guess that's on the right track, but I still don't know how to capture the value 'Fido'. I tried creating a constructor that accepts a String value, but that didn't work. I also tried creating a @XmlAttribute variable in the Name class called name, but that didn't work either. Please help.

[Bill Gorder]

Use @XmlAttribute for attributes and @XmlElement for elements. You do not need to create a name class.

@XmlRootElement  
@XmlAccessorType(XmlAccessType.FIELD)  
public class Pet {  
    @XmlAttribute  
    private String type;
    @XmlElement
    private String name;

    public Pet() {}  
    //getters and setters omitted
}

[Matthew Snow]

Thanks, that worked.

[Matthew Snow]

Here is another conundrum.

<data>
	<gradetables>
		<table id="1" >
			<bracket grade="A" score="90" />
			<bracket grade="B" score="80" />
			<bracket grade="C" score="70" />
		</table>
		<table id="2" >
			<bracket grade="A" score="85" />
			<bracket grade="B" score="75" />
			<bracket grade="C" score="65" />
		</table>
	</gradetables>
</data>

Here is the code I have in class Data:

	@XmlElementWrapper(name="gradetables")
	@XmlElementRef(name="gradetables", type=Table.class)
	private ArrayList<table> gradetables;

In class Table is where I'm unsure. I have a @XmlElement private Bracket bracket; which, when I run the code, gets set to the last bracket value (the C bracket). I thought I would create a transient ArrayList<Bracket> variable which I would instantiate in the constructor and put brackets.add(bracket); in the setBracket() method. However, it seems that JAXB doesn't call the getter/setter methods when unmarshalling the XML stream even though these variables are private. As a result, the ArrayList<Bracket> brackets variable is empty at runtime while the bracket variable is set to the last bracket value in the XML.

[Bill Gorder]

Kind of the same thing:

Data.java

@XmlRootElement(name = "data")
@XmlAccessorType(XmlAccessType.FIELD)
public class Data
{
    public Data()
    {

    }

    @XmlElementWrapper(name = "gradetables")
    @XmlElement(name = "table")
    private List<Table> tables = new ArrayList<Table>();

   //getters and setters omitted
}

Table.java

@XmlRootElement(name = "table")
@XmlAccessorType(XmlAccessType.FIELD)
public class Table
{
    public Table()
    {

    }
    @XmlAttribute(name = "id")
    private int   id;

    @XmlElement(name = "bracket")
    List<Bracket> brackets = new ArrayList<Bracket>();
    
    //getters and setters ommitted
}

Bracket.java

@XmlRootElement(name = "bracket")
@XmlAccessorType(XmlAccessType.FIELD)
public class Bracket
{
    public Bracket()
    {

    }
    @XmlAttribute(name = "grade")
    private String grade;

    @XmlAttribute(name = "score")
    private int    score;

    //getters and setters ommitted
}

[Matthew Snow]

Thank you.

[Matthew Snow]

Thanks for the help, but I've got another. Back to the Pet XML, here's what I got:

<pet type=dog>Fido</pet>

[g tsuji]

This would do.

@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
    "value"
})
@XmlRootElement(name = "pet")
public class Pet {
    @XmlValue
    protected String value;
    @XmlAttribute(name = "type")
    protected String type;

    //getters & setters

}

This kind of questions can go on no end. My cheat-sheet has this: make out a simple schema and use the jaxb code generator to generate the classes. That often is what fills the high percentage of the need. And the above is what I did.

ps You keep posting this kind of xml like type=dog. This is not it should appear in the xml.

[Matthew Snow]

Thanks g tsuji, that does work. For anyone wondering, codehaus has a nice maven jaxb plugin for generating code from an xml schema (http://www.altuure.com/2008/01/22/jaxb-quickstart-via-maven2/).

Unfortunately, my Pet bean extends another class and JAXB does not allow the use of @XmlValue on a class that derives another class. I guess I'm just going to have to rethink my code structure on this one.

[Matthew Snow]

Solved it, putting the @XmlValue element in the parent class has solved this instance as well and any other empty name element occurrences as well. Here is what the two classes look like:

public class Animal {
    @XmlValue  
    protected String value;
}

@XmlRootElement
public class Pet extends Animal {
    @XmlAttribute(name = "type")  
    private String type;  
  
    //getters & setters  for type & value
  
}