Variable One-to-one mapping

Question

i am working on variable one-to-one mapping. i am unable to figure out how to work on it. can anybody provide an example on how to implement it from java and toplink perspectives.

Answer 1

Thank you. I have gone through the links. i used class indicator field method. I am still getting error saying
"Exception Description: Missing descriptor for [class java.lang.String]. Verify that the descriptor has been properly registered with the Session."
My code and table structure is as below.
Interface - VariableOneToOne
Implementation classes: Phone and Email
Table Structure:
Employee Table:
ID (PK)
Name
TYPE (mapped as variable one-to-one)
C_ID(FK to eid and pid)
Phone Table:
pid (PK)
phnumber
Email Table:
eid (PK)
emailaddress
"TYPE" is of string type. "Phone" or "Email" is sent from this attribute. Toplink instantiates the respective class from the configurations specified in the variable one-to-one mapping of "TYPE" attribute in workbench.
The classes and interface code is as below:
Inteface:
package com.cts;
public interface VariableOneToOne {
     public int getId();
     public void setId(int id);
Employee Class:
package com.cts;
public class Employee2{
     protected int id;
     protected String name;
     protected String type;
     protected VariableOneToOne phone;
     protected VariableOneToOne email;
     public Employee2()
          this.id = 0;
          this.name = null;
          this.type = null;
          this.phone = null;
          this.email = null;
     public int getId() {
          return id;
     public void setId(int id) {
          this.id = id;
     public String getName() {
          return name;
     public void setName(String name) {
          this.name = name;
     public String getType() {
          return type;
     public VariableOneToOne getEmail() {
          return email;
     public void setEmail(VariableOneToOne email) {
          this.email = email;
     public VariableOneToOne getPhone() {
          return phone;
     public void setPhone(VariableOneToOne phone) {
          this.phone = phone;
     public void setType(String type) {
          this.type = type;
Email Class:
package com.cts;
public class Email2 implements VariableOneToOne {
     protected int id;
     protected String email;
     public Email2() {
          this.id = 0;
          this.email = null;
     public String getEmail() {
          return email;
     public void setEmail(String email) {
          this.email = email;
     public int getId() {
          return id;
     public void setId(int id) {
          this.id = id;
Phone Class:
package com.cts;
public class Phone2 implements VariableOneToOne {
     protected int id;
     protected String phone;
     public Phone2()
          this.id = 0;
          this.phone = null;
     public int getId() {
          return id;
     public void setId(int id) {
          this.id = id;
     public String getPhone() {
          return phone;
     public void setPhone(String phone) {
          this.phone = phone;
Please advice on resolving the issue.
Thanks in advance.