How to add implementation of JAXB-API to classpath

[Fernando Sanchez]

I'm a beginner at JAXB.

I don't know how to add the JAXB-API implementation that this code from a textbook needs (it is excuted without problems from NeatBeans), resulting in this error:

Exception in thread "main" javax.xml.bind.JAXBException: Implementation of JAXB-API has not been found on module path or classpath.
- with linked exception:
[java.lang.ClassNotFoundException: com.sun.xml.internal.bind.v2.ContextFactory]
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:278)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:421)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:721)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:662)
at clasesjaxb.Ejemplo1_JAXB.main(Ejemplo1_JAXB.java:28)
Caused by: java.lang.ClassNotFoundException: com.sun.xml.internal.bind.v2.ContextFactory
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at javax.xml.bind.ServiceLoaderUtil.nullSafeLoadClass(ServiceLoaderUtil.java:122)
at javax.xml.bind.ServiceLoaderUtil.safeLoadClass(ServiceLoaderUtil.java:155)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:276)
... 4 more

The classes in the project compile because I added to the Eclipse classpath jaxb-api.jar file (extracted from jaxb-ri-2.3.1.zip) but I have no idea how to add an implementation for that api.

[Stephan van Hulst]

Where did you get the JAXB RI zip from?

The problem is that you only added the API library to the class path, but not the implementation. Since I don't use Eclipse, I don't know if it allows you to separately specify which dependencies go on the classpath only at runtime, but if it does then there's where you would place the implementation library.

Issues with dependencies are MUCH easier to solve if you use Maven for your projects.

[Fernando Sanchez]

Stephan van Hulst wrote:Where did you get the JAXB RI zip from?

The problem is that you only added the API library to the class path, but not the implementation. Since I don't use Eclipse, I don't know if it allows you to separately specify which dependencies go on the classpath only at runtime, but if it does then there's where you would place the implementation library.

Issues with dependencies are MUCH easier to solve if you use Maven for your projects.

So, my situation is:
1. Only api I've found is jaxb-api.jar file (extracted from jaxb-ri-2.3.1.zip) which allows me to compile
2. Only implementation I've found eclipselink.jar (extracted from eclipselink-3.0.3.v202208190922-471432269c) allows me to run
3. The implementation and the api are incomptible



No clue what I could do.

[Stephan van Hulst]

You need to find the version of EclipseLink that is compatible with your version of JAXB.

Again, from where did you get the JAXB RI library from? And why did you choose that version?

[Tim Holloway]

Stephan van Hulst wrote:Where did you get the JAXB RI zip from?

The problem is that you only added the API library to the class path, but not the implementation. Since I don't use Eclipse, I don't know if it allows you to separately specify which dependencies go on the classpath only at runtime, but if it does then there's where you would place the implementation library.

Issues with dependencies are MUCH easier to solve if you use Maven for your projects.

Every Eclipse project can, if you wish, be configured to use whichever JDK installed in your system that you desire. You can add your own libraries and class directories into that project classpath as you wish,  And, in fact, you can define such items symbolically to make it easier and more portable between projects and/or other people's machines.

Beyond that, for testing and execution, each run profile that you define for a project can have its own classpath characteristics.

So definitely there's flexibility there.

As a further feature, if your project is defined to Eclipse as a Maven project. Eclipse can extend the project's classpath to reflect the Maven POM dependencies. So all can work in harmony.

[Fernando Sanchez]

Stephan van Hulst wrote:You need to find the version of EclipseLink that is compatible with your version of JAXB.

I downloaded the eclipselink-3.0.3.v202208190922-471432269c.zip file from Eclipse server: https://www.eclipse.org/eclipselink/#download and tried adding all the jar files (about 20) to my project CLASSPATH and also added a file called jaxb.properties in the same package as the domain classes with the following entry:

javax.xml.bind.context.factory=org.eclipse.persistence.jaxb.JAXBContextFactory

as explained here https://wiki.eclipse.org/EclipseLink/Examples/MOXy/JAXB/SpecifyRuntime

But the imports cannot be resolved:

The import javax.xml.bind cannot be resolved

Stephan van Hulst wrote:Again, from where did you get the JAXB RI library from? And why did you choose that version?

I can't remember where I downloaded it from, maybe from here: https://mvnrepository.com/artifact/com.sun.xml.bind/jaxb-ri/2.3.1 or maybe from here https://repo1.maven.org/maven2/com/sun/xml/bind/jaxb-ri/2.3.1/  

[Fernando Sanchez]

I think I've found the jaxb-runtime.jar compatible with jaxb-api.jar withing the same jaxb-ri-2.3.1.zip file.

Now I'm getting a different error when the code tries this:

JAXBContext context = JAXBContext.newInstance(Libreria.class);

Exception in thread "main" java.lang.NoClassDefFoundError: com/sun/istack/Pool
at com.sun.xml.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1156)
at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:165)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:577)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:297)
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:286)
at javax.xml.bind.ContextFinder.find(ContextFinder.java:409)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:721)
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:662)
at classjaxb.Ejemplo1_JAXB.main(Ejemplo1_JAXB.java:29)
Caused by: java.lang.ClassNotFoundException: com.sun.istack.Pool
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
... 10 more

However with NetBeans everything seems to work ok:

[Stephan van Hulst]

Do you have a reason you're using version 2.3 of the JAXB API? As far as I can tell, you're not using a Java EE 8 or older web application container, so you should be able to use the JAXB API version 3.0 without problems.

I got it to work in Eclipse, without Maven. Here's what I did:

Download the JAXB RI 3.0.2 standalone ZIP bundle.

Unpack the ZIP.

Add a new User Library in Eclipse. I named it "JAXB RI 3.0.2".

Add all JARs from the mod folder of the unpacked ZIP to the user library, except jaxb-jxc.jar and jaxb-xjc.jar.

Under Libraries of the project's Build Path, add the "JAXB RI 3.0.2" user library to the Classpath.

Run the application.

Here's the code I tested it with:

package com.example.jaxb;

import jakarta.xml.bind.annotation.*;

@XmlType(name = "Book", propOrder = {
  "name",
  "author",
  "publisher",
  "isbn"
})
final class BookXml {
  
  private final String name;
  
  private final String author;
  
  private final String publisher;
  
  private final String isbn;

  @SuppressWarnings("unused")
  private BookXml() {
    name      = null;
    author    = null;
    publisher = null;
    isbn      = null;
  }
  
  BookXml(String name, String author, String publisher, String isbn) {
    this.name      = name;
    this.author    = author;
    this.publisher = publisher;
    this.isbn      = isbn;
  }
  
  @XmlElement(name = "nombre", required = true)
  String getName() {
    return name;
  }

  @XmlElement(name = "autor", required = true)
  String getAuthor() {
    return author;
  }

  @XmlElement(name = "editorial", required = true)
  String getPublisher() {
    return publisher;
  }

  @XmlElement(name = "isbn", required = true)
  String getIsbn() {
    return isbn;
  }
}

package com.example.jaxb;

import java.util.*;

import jakarta.xml.bind.annotation.*;

import static java.util.Collections.unmodifiableList;

@XmlRootElement(name = "libreria")
@XmlType(name = "Library", propOrder = {
  "name",
  "place",
  "books"
})
final class LibraryXml {
  
  private final String name;
  
  private final String place;
  
  private final List<BookXml> books;
  
  @SuppressWarnings("unused")
  private LibraryXml() {
    name  = null;
    place = null;
    books = null;
  }
  
  LibraryXml(String name, String place, Collection<? extends BookXml> books) {
    this.name  = name;
    this.place = place;
    this.books = new ArrayList<>(books);
  }
  
  @XmlElement(name = "nombre", required = true)
  String getName() {
    return name;
  }

  @XmlElement(name = "lugar", required = true)
  String getPlace() {
    return place;
  }
  
  @XmlElementWrapper(name = "ListaLibro", required = true)
  @XmlElement(name = "Libro")
  List<BookXml> getBooks() {
    return unmodifiableList(books);
  }
}

package com.example.jaxb;

import java.io.*;
import java.nio.file.*;
import java.util.*;

import jakarta.xml.bind.*;

final class JaxbExample {
  
  public static void main(String... args) throws IOException {
    var library = new LibraryXml(
      "Prueba de libreria JAXB",
      
      "Vista Alegre, Carabanchel, Madrid",
      
      List.of(
        new BookXml(
          "Entornos de Desarrollo",
          "Alicia Ramos",
          "Garceta",
          "978-84-1545-297-3"
        ),
        
        new BookXml(
          "Acceso a Datos",
          "Maria Jesús Ramos",
          "Garceta",
          "978-84-1545-228-7"
        )
      )
    );
    
    var path = Paths.get("library.xml");
    
    try (
      var writer = Files.newBufferedWriter(path);
    ) {
      JAXB.marshal(library, writer);
    }
  }
}

And here is the output:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <libreria>    <nombre>Prueba de libreria JAXB</nombre>    <lugar>Vista Alegre, Carabanchel, Madrid</lugar>    <ListaLibro>        <Libro>            <nombre>Entornos de Desarrollo</nombre>            <autor>Alicia Ramos</autor>            <editorial>Garceta</editorial>            <isbn>978-84-1545-297-3</isbn>        </Libro>        <Libro>            <nombre>Acceso a Datos</nombre>            <autor>Maria Jesús Ramos</autor>            <editorial>Garceta</editorial>            <isbn>978-84-1545-228-7</isbn>        </Libro>    </ListaLibro> </libreria>

[Fernando Sanchez]

Thank you for the answer. I tried to follow exactly the same steps you tried but I can't get the code compiled:

1. Under Libraries of the project's Build Path, I added the "JAXB RI 3.0.2" user library to the Classpath
2. I added that that user library to the project Classpath

[Stephan van Hulst]

Yes, you need to change the package names from javax to jakarta.

Another thing, please don't quote entire posts, it makes the topic harder to read. If you want to reply to something specific, please quote only that part of the post.

[Fernando Sanchez]

Thank you for the answer, it finally worked fine. Sorry for quoting the whole previous message, but I coudn't find a button which specifically answered to the previous message in the thread and thought quoting was the only way to make it clear what I was answering too.

One last thing I wonder: why in the NetBeanst it isn't necessary to add this library whereas in Eclipse it is.

[Stephan van Hulst]

What version of Java are you using in NetBeans?

[Fernando Sanchez]

Stephan van Hulst wrote:What version of Java are you using in NetBeans?

It seems to be Java 1.8, I guess that's the default version (I had never used NetBeans before, contrary to Eclipse which I used to use when I worked in the software industry about 20 years ago).

Thanks again for your help.

[Stephan van Hulst]

JAXB was removed from the JDK with Java 11. So if you're working with a Java version older than 11, you don't need to include JAXB through an external library.