Java OO inheritance issue

Question

Hello,
I have a API written to provide service related implementation in which i have abstract class called com.api.XXXServiceInterface which needs to be implemented by every service provider and then deploy it in JNDI name space e.g.
public class myServiceProvider implements com.api.XXXServiceInterface
public void startService()
bind(this) //This method will bind this class into JNDI
while binding into JNDI, service provider will be binding his service class i.e. com.test.myServiceProvider which implements com.api.XXXServiceInterface from provided API
Now in my platform when i bind to JNDI to find specific service provider's service i will get com.test.myServiceProvider class object and i am trying to type cast it to com.api.XXXServiceInterface but this type casting is throwing ClassCastException class not found com.test.myServiceProvider as my platform will be running somewhere else where i do not have service provider's class object but i will have its super interface class com.api.XXXServiceInterface where i want to do something like
com.api.XXXServiceInterface service = (com.api.XXXServiceInterface)ctx.lookup("MerchantService");
service.startService(); //to start service providers service
How can I achieve this? Please provide me any suggestion and comments
Thanks

Answer 1

but basically this is not good code for two reasons:
a) instanceof takes a looong time :x
b) there are better ways:
take advantage of the overriding/dynamical bindings in java:
class A {
    public int getValue() { //could be declared abstract
        return 0;
class B extends A {
    int bValue = 50;
    public int getValue() {
        return bValue;
class C extends A {
    int cValue = 100;
    public int getValue() {
        return cValue;
A myObject = SelectedObject;
System.out.println(myObject.getValue()); //wil print 0 if Selected was an A-Object, 50 if it was an B-Object, 100 if it was an C-Object
...