Jeff Langr

51 articles

Working With Design Patterns: Odds and Ends

The Wikipedia page on Design Patterns contains a nice classification table for about 40 different patterns. I've discussed about 25 of these patterns in...

Working With Design Patterns: Abstract Factory

Like many design patterns, the abstract factory pattern and the builder pattern appear very similar in terms of their class structure. They are both...

Working With Design Patterns: Factory Method

Inheritance hierarchies containing an abstract base class present a small challenge for unit testing: How do common superclass methods get tested? Because you can't...

Building a Simple BlackBerry Application Interface

As I dig deep into building applications for the BlackBerry, I'd like to employ test-driven development (TDD). I've constructed a simple assertion-based framework, BBTest,...

A Unit Testing Framework for the BlackBerry

The software development scene currently offers an overwhelming menu of programming languages and frameworks. That's a good thing—it means that people are still trying...

Working With Design Patterns: Iterator

Iterator is a pattern? Come on, now! You've known how to step sequentially through a collection of objects since childhood. Programmer childhood, anyway. Remember that...

Working With Design Patterns: State

Conditional logic is essential to building any application, yet too much can make an application incomprehensible. Many of the applications I build require that...

Working With Design Patterns: Mediator

Unless you've been living in Antarctica, you've encountered the self-checkout line at the grocery store. And, if you're reading this article, well, you're a...

Working With Design Patterns: Interpreter

The Design Patterns book suggest that the interpreter pattern is the same as the composite design pattern, except for intent. A composite is an...

Working With Design Patterns: Chain of Responsibility

To understand the use of the chain of responsibility design pattern, think "chain of command." A request lands in Jane's inbox. Depending on the...

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