Anybody I don’t like, read this! :

com.superframework.core.base.Object object = new com.superframework.core.base.Object()

Sometimes one cannot avoid this rubbish in Java, even today. I do not wish my enemies to read such code, not in my code I want to be proud of!

I wonder how many times I have asked myself why Java is so complicated to read and write? Why I have to keep writing so many characters and lines of code to express a simple repetitive task? It’s appeared to me like Java language designers keep torturing developers by forcing us to use constructs invented 15+ years ago without an alternative.

But this one is simply an outrage. (more…)

Ever wondered why Eclipse/Netbeans keeps pausing for a while every now an then? Especially right at the time when you want to show something in the code to your dear colleages? It feelt embarrassing and awkward, didn’t it?

I found out that most of the time the IDE pauses because of Garbage Collector execution. The subtle little element in design of JVM, which usually does great job in relieving us developers from worrying about memory consumption, and most people are just happy that it does its job well and ignore it most of the time. However, the consequences of running Garbage Collector may surprise us if we simply ignore it. (more…)

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.

(more…)

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;
}

 

This site uses cookies to improve your experience. By using this site you agree to these cookies being set. More in our cookies policy

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close