java.lang.NoSuchMethodException: JAXB Unmarshalling Interfaces

Question

I am following the threads related to JAXB Marshalling / Unmarshalling for a while now.

I had run into problems while i was trying to convert a Java Object into XML, which had some interfaces in it. Later i found out this can be solved using EclipseLink's MOxy. @Bdoughan's articles here http://blog.bdoughan.com/2012/07/jaxb-no-annotations-required.html and answers were very helpful. But now, i have problems when i am trying to unmarshal the same XML file generated back into Java Objects.

This is the interface.

public interface TimePeriod extends Serializable{

/**
 * Return the end Time of the Time Period
 */
public Date getEndDate();

/**
 * Return the startTime of the Time Period
 */
public Date getStartDate();

/**
 * Sets the startTime of the Time period
 */
public void setStartDate(Date newStartDate);

/**
 * Sets the endTime of the Time period
 */
public void setEndDate(Date newEndDate);

}

One of the Implementations

TaskStepTimePeriod

public class TaskStepTimePeriod implements TimePeriod {

private Date taskStartDate;
private Date taskEndDate;

@Override
public Date getEndDate() {
    return taskEndDate;
}

@Override
public Date getStartDate() {
    return taskStartDate;
}


public void setTaskStartDate(Date newVal) {
    this.taskStartDate = newVal;
}


public void setTaskEndDate(Date newVal) {
    this.taskEndDate = newVal;
}

@Override
public void setStartDate(Date newStartDate) {
    this.taskStartDate = newStartDate;
}

@Override
public void setEndDate(Date newEndDate) {
    this.taskEndDate = newEndDate;
}

}

Marshalled XML

<?xml version="1.0" encoding="UTF-8"?>
<plannedProgram>
  <taskStep>
     <endDate>2014-07-31T12:00:00.262+05:30</endDate>
     <startDate>2014-06-01T12:00:00.262+05:30</startDate>
  </taskStep>
</plannedProgram>

So when i try to Unmarshall, i get this error stacktrace..

 Exception in thread "main" Local Exception Stack: 
  Exception [EclipseLink-63] (Eclipse Persistence Services -      2.6.1.v20150916-55dc7c3):       org.eclipse.persistence.exceptions.DescriptorException
  Exception Description: The instance creation method      [com.cts.axb.model.TimePeriod.<Default Constructor>], with no parameters,    does not exist, or is not accessible.
  Internal Exception: java.lang.NoSuchMethodException:    com.cts.axb.model.TimePeriod.<init>()
  Descriptor: XMLDescriptor(com.cts.axb.model.TimePeriod --> [])

It says no default constructor, but in an interface? Would really appreciate some pointers on what have i done wrong?

Have i missed annotating any elements in the classes?

My Unmarshalling code.!

 try {
         context = JAXBContext.newInstance(PlannedProgram.class);    
         Unmarshaller jaxbUnmarshaller = context.createUnmarshaller();
         newMaintProg = (PlannedProgram) jaxbUnmarshaller.unmarshal(file);
         System.err.println("XML file succesffuly read");
     } catch (JAXBException e) {
         System.err.println("Error Reading /  Unmarshalling the XML file "+ e);          
     }  

Answer 1

Please see https://jaxb.java.net/guide/Mapping_interfaces.html . Sections 3.2.2 and 3.2.3 are the most relevant.

Though, may be you just could specify concrete type in PlannedProgram , eg

private TaskStepTimePeriod taskStep;