Building an extensible architecture
TL;DR
Subtype polymorphism is great for adding more entity types. Pattern matching is a better choice for adding more functionality. In many use cases, it’s likelier that more functionality is requested than that more entity types are requested.
In this article, we implement a program based on a set of simple requirements. First, we implement it using subtype polymorphism, then using pattern matching. Given these implementations, we add two more requirements and compare the necessary changes to implement the new requirements.
Disclaimer
When use the term pattern matching, I’m referring to a limited subset. …
An introduction to Optional.flatMap
TL;DR
null is bad for representing the absence of a value, use Optionals instead. Use Optional.flatMap to chain multiple operations that might not return a value.
The problem with null
Let’s quickly recap what nullis and what problem it entails.
The language Java allows every non-primitive variable to take the value null. If a variable holds the value null, then all method calls to it will fail with a NullPointerException at runtime. The compiler can only give limited hints if a method call on a variable is safe. Therefore, the programmer needs to make assumptions if a method call is safe. If he is wrong…
Fabian Böller
I’m a senior software engineer working in Bonn at LeanIX. I write about software development best practices across multiple programming languages.
