600+ Scala Interview Questions Practice Test

1. **flatMap** in Scala Collections: The correct answer is **b) It applies a function to each element of a collection and flattens the result.** `flatMap` is used when you want to transform each element of a collection into another collection, and then you want to work with all the elements from these nested collections as if they were in a single flat collection. For example, if you have a collection of strings and you want to create a collection of their lengths, you can use `flatMap` to flatten this collection of numbers (integers representing lengths) into a single list.2. **Purpose of case classes in Scala:** The correct answer is **a) To facilitate pattern matching.** Case classes in Scala are designed to make it easy to deconstruct instances for pattern matching with the help of auto-generated methods like `equals`, `hashCode`, and `toString`. They are immutable by default, which makes them safer for pattern matching as their state won’t change during pattern matching.3. **Scala Feature for Generic Classes/Methods:** The correct answer is **d) Type parameterization.** Scala’s type parameterization (generics) allows developers to write classes and methods that can operate on any data type, with the compiler ensuring type safety at compile time. This avoids runtime errors associated with incorrect data types and promotes code reuse and abstraction.

4. **Significance of the Option Type in Scala:** The correct answer is **a) A collection that can contain zero or one element of a specified type.** The `Option` type is a container that encapsulates an optional value, which can either be `Some(value)` if the value is present or `None` if it is absent. This helps in handling the absence of values explicitly and avoids runtime exceptions related to null references.

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