java listen to ContextRefreshedEvent

A ContextRefreshEvent occurs

when an ApplicationContext gets initialized or refreshed.

so you are on the right track.

What you need to do is declare a bean definition for classX.

Either with @Component and a component scan over the package it's in

@Component
public class X implements ApplicationListener<ContextRefreshedEvent> {
    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
       //do something if all apps have initialised
    }
}

or with a <bean> declaration

<bean class="some.pack.X"></bean>

Spring will detect that the bean is of type ApplicationListener and register it without any further configuration.

Later Spring version support annotation-based event listeners. The documentation states

As of Spring 4.2, you can register an event listener on any public method of a managed bean by using the @EventListener annotation.

Within the X class above, you could declare an annotated method like

@EventListener
public void onEventWithArg(ContextRefreshedEvent event) {
}

or even

@EventListener(ContextRefreshedEvent.class)
public void onEventWithout() {

}

The context will detect this method and register it as a listener for the specified event type.

The documentation goes into way more detail about the full feature set: conditional processing with SpEL expression, async listeners, etc.

---

Just FYI, Java has naming conventions for types, variables, etc. For classes, the convention is to have their names start with an uppercase alphabetic character.

Spring >= 4.2

You can use annotation-driven event listener as below :

@Component
public class classX  {

    @EventListener
    public void handleContextRefresh(ContextRefreshedEvent event) {

    }
}

the ApplicationListener you want to register is defined in the signature of the method.