Home » Design Patterns » Page 19

Tag Archives: Design Patterns

Concurrency Pattern: Producer and Consumer

java-interview-questions-answers

In my career spanning 15 years, the problem of Producer and Consumer is one that I have come across only a few times. In most programming cases, what we are doing is performing functions in a synchronous fashion where the JVM or the web container handles the complexities of multi-threading on its own. However, when writing certain kinds of use ...

Read More »

GWT MVP made simple

GWT Model-View-Presenter is a design pattern for large scale application development. Being derived from MVC, it divides between view and logic and helps to create well-structured, easily testable code. To help lazy developers like me, I investigate how to reduce the amount of classes and interfaces to write when using declarative UIs. Classic MVP You know how to post a ...

Read More »

The Wizard Design Pattern

We all love wizards…. (Software wizards I mean). We are always happy to jump on those ”Next” buttons like we were dancing the funky chicken on our… well you get the point. So today we bring you your beloved wizard into your coding experience. Let’s jump right into an example. Say you want to design a ConservativePerson class. import java.util.List; ...

Read More »

Musing on mis-usings: ‘Powerful use, Damaging misuse’

There’s an old phrase attributed to the former British Prime Minister Benjamin Disraeli which states there are three types of lies: “lies, damn lies and statistics”.  The insinuation here is that statistics are so easy to make up they are unreliable.  However, statistics are extensively used in empiracle science so surely they have some merit? In fact, they have a ...

Read More »

Programming antipatterns

  Did you ever do a code review where you recorded an extremely high amount of WTF/m? And did you ever wonder what the cause of all this bad code is? Most of the time cause number 1 are the use of design and coding antipatterns. If you like definitions, here is one: An AntiPattern is a literary form that ...

Read More »

Java EE6 Decorators: Decorating classes at injection time

A common design pattern in software is the decorator pattern. We take a class and we wrap another class around it. This way, when we call the class, we always pass trough the surrounding class before we reach the inner class. Java EE 6 lets us create decorators through CDI, as part of their AOP features. If we want to ...

Read More »

Poor man’s approach in practice

One day we ran into problem when an application was randomly starting using more CPU resources as usual. It continued picking more and more CPU resources from time to time. Thread dump showed many threads though we couldn’t understand wich of them is problematic…and I remembered about poor man’s profiler and its approach: the stack that’s all we need to! ...

Read More »

Design Patterns in the JDK

Brian Du Preez, our JCG partner from Zen in the art of IT has made a very fine job of collecting the most common design patterns found in the JDK. The pattern list is indeed impressive and long, so let us babble no more and present it to you. I saw an article (well more of a rant) the other day, by ...

Read More »

Using the State pattern in a Domain Driven Design

java-interview-questions-answers

Domain driven design (DDD) is an approach to developing software where the complexity of the problem is addressed by connecting the implementation to an evolving model of the core business concepts. The term was coined by Eric Evans and there is a DDD dedicated site which promotes its use. According to their definition (Glossary of Domain-Driven Design Terms), DDD is ...

Read More »