This content originally appeared on Level Up Coding - Medium and was authored by Maximiliano Contieri
Code Smell 181 — Nested Classes
Nested or Pseudo-Private Classes seem great for hiding implementation details.
TL;DR: Don’t use nested classes
Problems
- Bijection fault to real world concepts.
- Lack of testability
- Lack of reuse
- Scopes and namespaces complexity
Solutions
- Make the class public
- Keep the public class under your own namespace/module.
- Use a Facade to the external world to hide it.
Context
Some languages allow us to create private concepts that only live inside a more significant idea.
These classes are harder to test, harder to debug, and reuse.
Sample Code
Wrong
class Address {
String description = "Address: ";
public class City {
String name = "Doha";
}
}
public class Main {
public static void main(String[] args) {
Address homeAddress = new Address();
Address.City homeCity = homeAddress.new City();
System.out.println(homeAddress.description + homeCity.name);
}
}
// The output is "Adress: Doha"
//
// If we change privacy to 'private class City'
//
// We get an error " Address.City has private access in Address"Right
class Address {
String description = "Address: ";
}
class City {
String name = "Doha";
}
public class Main {
public static void main(String[] args) {
Address homeAddress = new Address();
City homeCity = new City();
System.out.println(homeAddress.description + homeCity.name);
}
}
// The output is "Adress: Doha"
//
// Now we can reuse and test City conceptDetection
[X] Automatic
Since this is a language feature, we can detect it and avoid its usage.
Tags
- Hierarchies
Conclusion
Many features are bloated with complex features.
We seldom need these new pop culture features.
We need to keep a minimal set of concepts.
More Info
Disclaimer
Code Smells are just my opinion.
Credits
Photo by Dana Ward on Unsplash
Developers are drawn to complexity like moths to a flame, frequently with the same result.
Neal Ford
Software Engineering Great Quotes
This article is part of the CodeSmell Series.
How to Find the Stinky parts of your Code
Code Smell 181 — Nested Classes was originally published in Level Up Coding on Medium, where people are continuing the conversation by highlighting and responding to this story.
This content originally appeared on Level Up Coding - Medium and was authored by Maximiliano Contieri
Maximiliano Contieri | Sciencx (2022-11-23T02:31:15+00:00) Code Smell 181 — Nested Classes. Retrieved from https://www.scien.cx/2022/11/23/code-smell-181-nested-classes/
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