97 Things Every Java Programmer Should Know

Chapter 31. Hey Fred, Can You Pass Me the HashMap?

Kirk Pepperdine

Picture the scene: an old, cramped office with several old wooden desks set back-to-back. Each desk equipped with an old black rotary phone and ashtrays dotted about. On one of the desks is a black HashMap that contains an ArrayList filled with customer data. Sam, needing to contact Acme Inc., scans the office looking for the HashMap. Eyes darting, he spots the HashMap and shouts out, “Hey Fred, can you please pass me the HashMap?” Can you picture that…yup, I didn’t think so…

An important part of writing a program is the development of a vocabulary. Each word in that vocabulary should be an expression of something that is part of the domain we’re modeling. After all, it is this code expression of our model that others will have to read and understand. Consequently, our choice of vocabulary can either help or hinder understanding of our code. Oddly enough, the choice of vocabulary impacts much more than readability: the words we use affect how we think about the problem at hand, which, in turn, impacts the structure of our code, our choice of algorithms, how we shape our APIs, how well the system will fit our purpose, how easily it will be maintained and extended, and, finally, how well it will perform. Yes, the vocabulary we develop when writing code matters a lot. So much so that keeping a dictionary at hand can ...