JAXB ClassCastException

Question

Hi
Hope someone can help here
[EDIT] Xjc compiles cpu.xsd perfectly fine[EDIT]
I'm trying to unmarshal an xml document and i get the following error (When running in Netbeans:
init:
deps-jar:
compile:
run:
java.lang.ClassCastException: javax.xml.bind.JAXBElement cannot be cast to generated.CPU
        at jaxbtest.Main.main(Main.java:24)
BUILD SUCCESSFUL (total time: 0 seconds)The following are my source documents:
cpu.xml
<?xml version="1.0" encoding="UTF-8"?>
<cpu xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="cpu.xsd">
     <numcores>4</numcores>
     <registers>32</registers>
</cpu>cpu.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
     <xsd:element name="cpu" type="CPU"/>
     <xsd:complexType name="CPU">
          <xsd:sequence>
               <xsd:element name="numcores" type="xsd:int"/>
               <xsd:element name="registers" type="xsd:int"/>
          </xsd:sequence>
     </xsd:complexType>
</xsd:schema>Main.java
package jaxbtest;
import generated.*;
import javax.xml.bind.*;
import java.io.*;
public class Main
     public static void main(String[] args)
          try
               JAXBContext jc = JAXBContext.newInstance("generated");
               Unmarshaller u = jc.createUnmarshaller();
               CPU cpu = (CPU) u.unmarshal(new File("cpu.xml"));
               System.out.println(cpu.getRegisters());
          catch (Exception e)
               e.printStackTrace();
}ObjectFactory.java (Created by xjc)
package generated;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.XmlElementDecl;
import javax.xml.bind.annotation.XmlRegistry;
import javax.xml.namespace.QName;
@XmlRegistry
public class ObjectFactory {
    private final static QName _Cpu_QNAME = new QName("", "cpu");
     * Create a new ObjectFactory that can be used to create new instances of schema derived classes for package: generated
    public ObjectFactory() {
     * Create an instance of {@link CPU }
    public CPU createCPU() {
        return new CPU();
     * Create an instance of {@link JAXBElement }{@code <}{@link CPU }{@code >}}
    @XmlElementDecl(namespace = "", name = "cpu")
    public JAXBElement<CPU> createCpu(CPU value) {
        return new JAXBElement<CPU>(_Cpu_QNAME, CPU.class, null, value);
}CPU.java (Also created by xjc)
package generated;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlType;
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "CPU", propOrder = {
    "numcores",
    "registers"
public class CPU {
    protected int numcores;
    protected int registers;
     * Gets the value of the numcores property.
    public int getNumcores() {
        return numcores;
     * Sets the value of the numcores property.
    public void setNumcores(int value) {
        this.numcores = value;
     * Gets the value of the registers property.
    public int getRegisters() {
        return registers;
     * Sets the value of the registers property.
    public void setRegisters(int value) {
        this.registers = value;
}Am I doing anything wrong? Can anyone please help?
Thanks very much.
bish

Answer 1

HI,
I was looking for good solution to this problem, better than this one.
Your solution is just temporary, I do not want to cast twice. So after own research I found out that this error
is caused when JAXB cannot find main type. It will happen if main tag has type declared outside this tag:
<xs:element name="egzam">
        <xs:unique name="egzamId">
            <xs:selector xpath="." />
            <xs:field xpath="@id" />
        </xs:unique>
    </xs:element>
    <xs:complexType name="egzam">
        <xs:sequence minOccurs="1" maxOccurs="unbounded">
            <xs:element name="question" type="egzamQuestion">
                <xs:unique name="questionId">
                    <xs:selector xpath="." />
                    <xs:field xpath="@id" />
                </xs:unique>
            </xs:element>
        </xs:sequence>
        <xs:attribute name="id" type="xs:string" use="required" />
    </xs:complexType>If we do not define external type in main tag, classCastException dissapear:
<xs:element name="egzam">
        <xs:complexType>
            <xs:sequence minOccurs="1" maxOccurs="unbounded">
                <xs:element name="question" type="egzamQuestion">
                    <xs:unique name="questionId">
                        <xs:selector xpath="." />
                        <xs:field xpath="@id" />
                    </xs:unique>
                </xs:element>
            </xs:sequence>
            <xs:attribute name="id" type="xs:string" use="required" />
        </xs:complexType>
        <xs:unique name="egzamId">
            <xs:selector xpath="." />
            <xs:field xpath="@id" />
        </xs:unique>
    </xs:element>Edited by: maciekcom on Nov 1, 2008 2:24 PM