Clean architecture isn’t optional — it’s survival.
7 Software Engineering Principles I Never Skip in Android Projects
From scalability to sanity, these foundational principles have guided my Android development journey — saving time, reducing bugs, and making codebases a joy to work with.
Not a Medium Member? “Read For Free”
You can chase the latest libraries — Jetpack Compose, KMM, Hilt — but if your fundamentals are shaky, your app will eventually crumble under complexity.
After building and contributing to numerous Android projects over the years, I’ve realized that software engineering principles are the difference between code that just works… and code that lasts.
In this article, I’ll walk you through 7 core principles I apply to every Android project — regardless of tech stack, architecture pattern, or team size.
1. Single Responsibility Principle (SRP)
One class, one job.
This is the hill I’ll die on. A MainActivity that also handles networking? A ViewModel that's 900 lines long? Big red flags.
In practice:
- Split responsibilities: use
UiState,UiEvent, andUseCaselayers. - Compose Screens should delegate UI logic to ViewModels only.
- Avoid “God classes” — they’re hard to test, harder to maintain.
Jetpack Compose + SRP = Lightweight Composables and Clean Architecture that scales.
2. DRY: Don’t Repeat Yourself
Repetition breeds bugs and burnout.
If you’re copy-pasting the same error handling, loading states, or Modifier.padding(16.dp)… it's time to refactor.
Use shared components and extensions:
fun Modifier.defaultPadding() = this.padding(16.dp)- Centralize error handling logic
- Create reusable UI components
- Abstract network state into a sealed class
Example: Create a UiState<T> sealed class with Loading, Success, and Error once, and reuse it across screens.
3. KISS: Keep It Simple, Stupid
Just because you can use coroutines, Flow, and channels doesn’t mean you should — not all at once.
Simplicity beats cleverness. Especially in Android where too many layers = performance hits and onboarding nightmares.
Tips to stay simple:
- Use
StateFlowinstead ofLiveData+ custom observers - Don’t over-abstract early
- Avoid unnecessary generics, reflection, or metaprogramming
Rule of thumb: If you have to explain it twice, it’s too complex.
4. YAGNI: You Aren’t Gonna Need It
That “just-in-case” feature? Probably never gonna happen.
Premature optimization leads to bloated code and wasted time. Focus on what’s needed now.
Example:
Don’t build an offline mode, multilingual support, or complex themes unless:
- It’s a business requirement
- You’re shipping it this sprint
“Maybe one day” = “Definitely a maintenance headache later”
5. Favour Composition Over Inheritance
Android encourages composition — embrace it.
Inheritance is rigid. Composition is flexible. Prefer delegating behaviour via interfaces and high-order functions.
Example: Compose makes this easy
@Composable
fun ErrorScreen(onRetry: () -> Unit)Pass behaviours down instead of subclassing screens or fragments.
Easier testing
Better modularity
More reusable components
6. Explicit > Implicit
If something is “magic,” it better be documented or obvious.
Implicit dependencies — like using Hilt without @Inject fields clearly marked — cause confusion.
Practice:
- Make dependencies obvious in constructors
- Avoid magic strings and reflection where possible
- Prefer clarity over brevity
When a dev joins your project, they shouldn’t need a seance to figure out how navigation or DI works.
7. Design for Testability
If it’s not testable, it’s probably not well designed.
No, you don’t have to hit 100% coverage. But writing testable code means writing clean code.
Patterns I follow:
- Business logic in UseCases
- Keep ViewModels thin
- Use fake data sources for testing
- Prefer interfaces over concrete implementations
Tip: Jetpack Compose’s @Preview is not a replacement for real UI tests!
Conclusion
No matter how modern your stack is — Jetpack Compose, Kotlin Multiplatform, or AI-powered UIs — if your fundamentals are weak, your app won’t scale.
These software engineering principles have saved me countless times:
- During painful bug hunts
- In fast-paced feature releases
- While onboarding new devs
Start applying them today, and your future self (and your teammates) will thank you.
