Scala Interview Questions and Answers
Freshers / Beginner level questions & answers
Ques 1. What is Scala and why is it used?
Scala is a programming language that combines object-oriented and functional programming. It is used for building scalable and concise applications on the Java Virtual Machine (JVM).
Ques 2. Explain the difference between val and var in Scala.
val is a keyword used for defining immutable variables, while var is used for defining mutable variables.
Ques 3. What is the significance of 'Option' in Scala?
'Option' is used to represent optional values. It can either be 'Some(value)' if a value is present or 'None' if the value is absent.
Ques 4. What is a higher-order function?
A higher-order function is a function that takes other functions as parameters or returns functions as results.
Ques 5. How does Scala handle null values?
Scala encourages the use of 'Option' types to represent optional values instead of using null. 'Some' is used for a present value, and 'None' is used for an absent value.
Ques 6. Explain the 'yield' keyword in Scala.
In a 'for' comprehension, 'yield' is used to produce a value that is included in the resulting collection. It is often used to transform and filter data.
Ques 7. How does Scala handle exceptions?
Scala uses the 'try', 'catch', and 'finally' blocks to handle exceptions. However, it does not distinguish between checked and unchecked exceptions.
Ques 8. What is the purpose of the 'case' keyword in Scala?
The 'case' keyword is used to define classes for pattern matching. It automatically generates equals, hashCode, and toString methods, making it suitable for use in pattern matching and collections.
Ques 9. What are the advantages of using the 'Option' type over null in Scala?
Using 'Option' type forces the developer to handle the absence of a value explicitly, reducing the likelihood of null pointer exceptions. It leads to safer and more robust code.
Ques 10. Explain the 'yield' keyword in the context of Scala collections.
In the context of Scala collections, 'yield' is used within a 'for' comprehension to produce elements for the resulting collection. It is often used for transforming and filtering data.
Ques 11. What is the 'type' keyword used for in Scala?
The 'type' keyword is used to define type aliases in Scala. It allows developers to create alternative names for existing types, improving code readability and maintainability.
Ques 12. What is the purpose of the 'Seq' trait in Scala?
'Seq' is a trait in Scala that represents sequences—ordered collections of elements. It is a subtrait of 'Iterable' and provides methods for indexing, length, and more.
Ques 13. Explain the 'copy' method in case classes.
The 'copy' method is automatically generated for case classes in Scala. It allows you to create a new instance of the case class with some fields modified, providing a convenient way to copy and update objects.
Ques 14. Explain the 'partition' method in Scala collections.
The 'partition' method in Scala collections divides a collection into two parts based on a predicate. Elements that satisfy the predicate are placed in one part, while the rest go into the other part.
Ques 15. Explain the 'zip' method in Scala collections.
The 'zip' method in Scala collections combines two collections element-wise, creating a new collection of pairs. If the original collections have different lengths, the resulting collection will have the length of the shorter one.
Most helpful rated by users:
- Explain the difference between val and var in Scala.
- What is a higher-order function?
- Explain the 'yield' keyword in Scala.
- What is the purpose of the 'case' keyword in Scala?
- What are the advantages of using the 'Option' type over null in Scala?
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