Java – use JAXB to handle missing nodes

I am currently using JAXB to parse XML files I generated the required classes through the XSD file However, the XML file I received does not contain all the nodes declared in the generated class Here is an example of my XML file structure:

<root>
<firstChild>12/12/2012</firstChild> 
<secondChild>
<firstGrandChild>
<Id>
  </name>
  <characteristics>Description</characteristics> 
  <code>12345</code>
</Id>
</firstGrandChild>
</secondChild>
</root>

I face the following two situations:

>The node < name > exists in the generated class but not in the XML file > the node has no value

In both cases, the value is set to null I want to be able to distinguish when the node does not exist in the XML file and when it exists but has a null value Despite my search, I haven't come up with a way Any help is very welcome

Thank you very much for your time and help

to greet

Solution

The JAXB (JSR - 222) implementation does not call the set method for missing nodes You can place logic in the set method to track whether it has been called

public class Foo {

    private String bar;
    private boolean barSet = false;

    public String getBar() {
       return bar;
    }

    public void setBar(String bar) {
        this.bar = bar;
        this.barSet = true;
    }

}

UPDATE

JAXB also treats an empty node as a value with an empty string

Java model

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Root {

    private String foo;
    private String bar;

    public String getFoo() {
        return foo;
    }

    public void setFoo(String foo) {
        this.foo = foo;
    }

    public String getBar() {
        return bar;
    }

    public void setBar(String bar) {
        this.bar = bar;
    }

}

demonstration

import java.io.File;
import javax.xml.bind.*;

public class Demo {

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

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum15839276/input.xml");
        Root root = (Root) unmarshaller.unmarshal(xml);

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

}

input. XML / output

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
    <foo></foo>
</root>