Use cases / Interactors in Android Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Use Case (Interactor) in Android app architecture?

A Use Case, also called an Interactor, is a class that contains the business logic of the app. It handles a specific task or action, like fetching data or processing user input, separate from UI or data layers.

beginner

Why should Use Cases be separate from UI and data layers?

Separating Use Cases keeps business logic independent. This makes the app easier to test, maintain, and change without affecting UI or data code.

intermediate

In Kotlin, how might a simple Use Case class look?

A Use Case class usually has a single public function, like `execute()`, that performs the task. It can use repositories to get or save data.

intermediate

What role do repositories play in Use Cases?

Repositories provide data to Use Cases. Use Cases ask repositories for data or tell them to save data, keeping data access details hidden from the business logic.

intermediate

How do Use Cases improve app testing?

Because Use Cases contain business logic separate from UI and data, you can test them easily by giving fake data sources and checking the results without running the full app.

What is the main responsibility of a Use Case (Interactor)?

A Handle user interface rendering

B Store data in a database

C Handle network communication

D Manage business logic for a specific task

Use Cases focus on business logic, not UI or data storage.

Why do we separate Use Cases from UI code?

A To make UI code more complex

B To mix data and UI logic

C To keep business logic testable and independent

D To slow down app performance

Separating Use Cases keeps business logic independent and easier to test.

Which layer typically provides data to Use Cases?

A UI layer

B Repository layer

C Network layer

D ViewModel layer

Repositories provide data to Use Cases, hiding data source details.

What is a common function name in a Use Case class?

A execute()

B render()

C saveData()

D loadUI()

Use Cases often have an execute() function to run their task.

How do Use Cases help with app testing?

A By making business logic independent and testable

B By mixing UI and data code

C By requiring the full app to run

D By hiding business logic inside UI

Use Cases separate business logic so it can be tested without UI or data dependencies.

Explain what a Use Case (Interactor) is and why it is important in Android app architecture.

Think about how your app handles tasks behind the scenes, separate from what the user sees.

Describe how Use Cases interact with repositories and why this separation matters.

Imagine a waiter (Use Case) asking the kitchen (repository) for food without knowing how the kitchen works.