Scala is a high-level programming language that combines object-oriented and functional programming in one concise. Below are some Scala interview questions and answer
Scala interview questions
- What is the difference between a Java future and a Scala future?
- What is a companion object?
- List different types of literals available in Scala?
- What is a applicative?
- Explain the difference between a trait and an abstract class?
- What do you mean by implicit parameters?
- How does yield work in Scala?
- What is auxiliary constructor in Scala?
- Please explain closure is Scala?
- What is Scala option?
- List Types of identifiers available in Scala?
- Explain function currying in Scala?
- What is a higher-order function in Scala?
- Explain trait in Scala and its uses?
- Explain BitSet in Scala?
- List the default imports are available in Scala Language?
- What is Monad in Scala?
- What is "Type Inference" in Scala?
- Explain what is Unit in Scala?
- What is PreDef in Scala?
- Tell the advantages of companion objects when used in Scala?
- What do you mean by a case class in scala?
- What do you understand by apply and unapply methods in scala?
- Differentiate between Array and List in Scala.
- What do you understand by an implicit parameter in Scala ?
- What do you understand by tail recursion in Scala ?
- What do you mean by a Scala map?
- List the advantages of using scala over other functional programming languages.
- Which Scala library is used for the functional programming?
- Differentiate Nil, Null, None, and Nothing in scala.
Instead of having static methods or variables, scala has singleton or companion objects. These objects are then compiled to classes which have static methods. Some advantages of these companion objects are listed below:
- These are beneficial as they can be used for encapsulating things. They also act as a bridge and hence functional and object-oriented programs can be written easily.
- These companion objects also help in keeping the scala programming code more concise because the static keyword need not be added to each and every attribute.
- A clear separation between the static and non-static methods is maintained with the help of these companion objects.
- Apply method- this method is used to assemble an object from its components. For eg.- if an employee object needs to be created, then the two components namely- first name and last name should be used and should be composed using the apply method.
- Unapply method- when we want to decompose the objects from its components, then we make use of this unapply method. Reverse process is followed while making use of the unapply method. So, the employee object can be decomposed into two components namely- first name and last name.
- An array is a sequential mutable data structure. Whereas, a list is an immutable recursive data structure.
- In scala, an array is an invariant. Whereas, a list is a covariant data structure.
- The size of an array is fixed and cannot be changed easily. Whereas, the size of a list may increase or decrease based on the operations performed by it.
By default, immutable map is supported by scala. To use the mutable map, the programmer needs to import the “scala.collection.mutable”. It is an explicit class. “mutable.map” is the syntax for using the mutable and immutable class in the same program. To access the immutable class, we just have to use the name of the map and it can be accessed.
- As the name suggests, it is a scalable programming language. It is highly scalable. Its high maintainability, productivity, and testability features make it more usable which turns out to be an advantage and hence it is preferred more.
- Scala consists of singleton and companion objects. These objects in scala, unlike the JVM languages provide a clearer solution to every problem.
- The need of ternary operator gets eliminated in scala as “if blocks”, “for-yield loops”, and “code” in braces return a value.
- Nil- it is used to initialize an empty list since it is an object which extends list.
- Null- null in scala is used to provide compatibility with the java null keyword or to provide a type for the null keyword. It also represents the absence of type information for complex types.
- None- the “none” pattern in scala is used to remove null values from the scala code.
- Nothing- it is used for providing the return type for the operations that can affect the normal flow of program.
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