XmlJavaTypeAdapter not being detected

java, jaxb

Solution

The following should help:

FOO AS ROOT OBJECT

When `@XmlJavaTypeAdapter` is specified at the type level it only applies to fields/properties referencing that class, and not when an instance of that class is a root object in your XML tree. This means that you will have to convert `Foo` to `AdaptedFoo` yourself, and create the `JAXBContext` on `AdaptedFoo` and not `Foo`.

Marshal

package forum11966714;

import javax.xml.bind.*;

public class Marshal {
    public static void main(String[] args) {
      Foo foo = new Foo("Adam", 34);

      try {
        JAXBContext jaxbContext = JAXBContext.newInstance(AdaptedFoo.class);
        Marshaller jaxbMarshaller = jaxbContext.createMarshaller();

        // output pretty printed
        jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

        jaxbMarshaller.marshal(new AdaptedFoo(foo), System.out);              
      } catch (JAXBException e) {
        e.printStackTrace();
      }   
    }
  }

AdaptedFoo

You will need to add an `@XmlRootElement` annotation to the `AdaptedFoo` class. You can remove the same annotation from the `Foo` class.

package forum11966714;

import javax.xml.bind.annotation.*;

@XmlRootElement
class AdaptedFoo {
    private String name;
    private int age;

    public AdaptedFoo() {
    }

    public AdaptedFoo(Foo foo) {
        this.name = foo.getName();
        this.age = foo.getAge();
    }

    @XmlAttribute
    public String getName() {
        return name;
    }

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

    @XmlAttribute
    public int getAge() {
        return age;
    }

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

FOO AS NESTED OBJECT

When `Foo` isn't the root object everything works the way you have it mapped. I have extended your model to demonstrate how this would work.

Bar

package forum11966714;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Bar {

    private Foo foo;

    public Foo getFoo() {
        return foo;
    }

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

}

Demo

Note that the JAXB reference implementation will not let you specify the `Foo` class when bootstrapping the `JAXBContext`.

package forum11966714;

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class Demo {
    public static void main(String[] args) {
        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(Bar.class);

            Unmarshaller jaxbUnmarshaller = jaxbContext.createUnmarshaller();
            File xml = new File("src/forum11966714/input.xml");
            Bar bar = (Bar) jaxbUnmarshaller.unmarshal(xml);

            Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
            jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
            jaxbMarshaller.marshal(bar, System.out);
        } catch (JAXBException e) {
            e.printStackTrace();
        }
    }
}

input.xml/Output

<?xml version="1.0" encoding="UTF-8"?>
<bar>
    <foo name="Jane Doe" age="35"/>
</bar>

Problem

Hopefully an easy one for JAXB experts: I am trying to marshal an immutable class that does not define a default no-arg constructor. I have defined an `XmlAdapter` implementation but it doesn't seem to be picked up. I have put together a simple self-contained example, which is still failing to work. Can anyone advise what I'm doing wrong? Immutable Class ``` @XmlJavaTypeAdapter(FooAdapter.class) @XmlRootElement public class Foo { private final String name; private final int age; public Foo(String name, int age) { this.name = name; this.age = age; } public String getName() { return name; } public int getAge() { return age; } } ``` Adapter and Value Type ``` public class FooAdapter extends XmlAdapter<AdaptedFoo, Foo> { public Foo unmarshal(AdaptedFoo af) throws Exception { return new Foo(af.getName(), af.getAge()); } public AdaptedFoo marshal(Foo foo) throws Exception { return new AdaptedFoo(foo); } } class AdaptedFoo { private String name; private int age; public AdaptedFoo() {} public AdaptedFoo(Foo foo) { this.name = foo.getName(); this.age = foo.getAge(); } @XmlAttribute public String getName() { return name; } public void setName(String name) { this.name = name; } @XmlAttribute public int getAge() { return age; } public void setAge(int age) { this.age = age; } } ``` Marshaller ``` public class Marshal { public static void main(String[] args) { Foo foo = new Foo("Adam", 34); try { JAXBContext jaxbContext = JAXBContext.newInstance(Foo.class); Marshaller jaxbMarshaller = jaxbContext.createMarshaller(); // output pretty printed jaxbMarshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); jaxbMarshaller.marshal(foo, System.out); } catch (JAXBException e) { e.printStackTrace(); } } } ``` Stack Trace ``` com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException: 1 counts of IllegalAnnotationExceptions Foo does not have a no-arg default constructor. this problem is related to the following location: at Foo at com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException$Builder.check(IllegalAnnotationsException.java:91) at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getTypeInfoSet(JAXBContextImpl.java:451) at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:283) at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:126) at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1142) at com.sun.xml.internal.bind.v2.ContextFactory.createContext(ContextFactory.java:130) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:248) at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:235) at javax.xml.bind.ContextFinder.find(ContextFinder.java:445) at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:637) at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:584) at Marshal2.main(Marshal2.java:11) ``` Note that I am using JDK 1.7.0_05.

Original source