After having the pleasure of building my code around CDI for couple of years, it feels very natural to use it to structure my code according to well-known patterns. CDI is a dependency injection mechanism designed to be used within Java EE application servers, and this could be perceived as a disadvantage. However, I want to show that it can be used and has great potential also in a Java SE application.

What is great about CDI is that it is much more than an injection mechanism. On top of this it provides also an elegant and powerful event passing mechanism. This feature can be nicely combined with Swing to build a GUI application based on MVC pattern.

It is really possible to efficiently combine CDI and Swing framework to build a Java GUI application rapidly and with a clear structure.


When tried to tune our near-production application, we came to problem when a single entity reference When tried to tune our near-production application, we came to problem when a single entity reference (not a collection) is loaded lazily. We used inheritance with this entity and hibernate JPA provider (as probably any other provider) inserts a proxy object into referencing entity instead of reference to real object loaded from database (as it is not yet loaded).

We came to a problem because we were casting super class to subclasses using instanceof. The problem is that proxy class is already a subclass and cannot be cast to a sibling class. It is a proxy only to super class instance, but it’s not possible to access methods of superclasses directly. The proxy never gets converted to real subclass. The problem is specified here, here and here. All described solutions depend on hibernate non-standard API to retrieve deproxied instance.

However, after lots of thinking…

… I found a solution to deproxy a class using standard Java and JPA API. Tested with hibernate, but does not require hibernate as a dependency and should work with all JPA providers.

Only one requirement – its necessary to modify parent class (Address) and add a simple helper method.

General idea: add helper method to parent class which returns itself. when method called on proxy, it will forward the call to real instance and return this real instance.

Implementation is a little bit more complex, as hibernate recognizes that proxied class returns itself and still returns proxy instead of real instance. Workaround is to wrap returned instance into a simple wrapper class, which has different class type than the real instance.

In code:

class Address {
  public AddressWrapper getWrappedSelf() {
    return new AddressWrapper(this);

class AddressWrapper {
  private Address wrappedAddress;


To cast Address proxy to real subclass, use following:

Address address = dao.getSomeAddress(...);
Address deproxiedAddress = address.getWrappedSelf().getWrappedAddress();
if (deproxiedAddress instanceof WorkAddress) {
  WorkAddress workAddress = (WorkAddress)deproxiedAddress;


List of elements in persistence.xml


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