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Scala Quiz – Information
| Quiz Name | Scala Quiz |
| Exam Type | MCQ (Multiple Choice Questions) |
| Category | Technical Quiz |
| Mode of Quiz | Online |
Scala Online Practice Tests
What is Scala?
a) A programming language
b) A database management system
c) A web development framework
d) An operating system
Answer: a) A programming language
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Explanation: Scala is a general-purpose programming language that is designed to be concise, expressive, and efficient. It is a statically typed language that is compatible with Java and can run on the JVM.
Which of the following is not a feature of Scala?
a) Functional programming
b) Object-oriented programming
c) Imperative programming
d) Declarative programming
Answer: c) Imperative programming
Explanation: Scala supports functional programming, object-oriented programming, and declarative programming. Imperative programming, on the other hand, involves changing the state of variables through a series of commands or instructions.
What is a trait in Scala?
a) A type of class
b) A method of inheritance
c) A programming language construct
d) A design pattern
Answer: a) A type of class
Explanation: A trait is a type of class in Scala that can be mixed into other classes to provide additional functionality. It is similar to an interface in Java.
What is the purpose of the ‘val’ keyword in Scala?
a) To declare a variable that can be reassigned
b) To declare a variable that cannot be reassigned
c) To declare a constant
d) To declare a function
Answer: b) To declare a variable that cannot be reassigned
Explanation: The ‘val’ keyword is used to declare a variable that is immutable and cannot be reassigned. It is similar to a final variable in Java.
What is the purpose of the ‘var’ keyword in Scala?
a) To declare a variable that can be reassigned
b) To declare a variable that cannot be reassigned
c) To declare a constant
d) To declare a function
Answer: a) To declare a variable that can be reassigned
Explanation: The ‘var’ keyword is used to declare a mutable variable that can be reassigned. It is similar to a regular variable in Java.
Which of the following is not a collection type in Scala?
a) List
b) Set
c) Map
d) Stack
Answer: d) Stack
Explanation: Stack is not a built-in collection type in Scala, although it can be implemented using other collection types.
What is a higher-order function in Scala?
a) A function that takes one or more functions as arguments
b) A function that returns another function
c) A function that can only be called from within another function
d) A function that takes no arguments
Answer: a) A function that takes one or more functions as arguments
Explanation: A higher-order function is a function that takes one or more functions as arguments or returns a function as its result. This is a fundamental concept in functional programming.
What is the purpose of the ‘yield’ keyword in a for loop in Scala?
a) To declare a new variable
b) To create a new collection
c) To filter elements in a collection
d) To loop through a collection
Answer: b) To create a new collection
Explanation: The ‘yield’ keyword is used to create a new collection from the elements in the original collection that meet certain criteria.
What is a case class in Scala?
a) A class that is used for pattern matching
b) A class that cannot be extended
c) A class that is used for serialization
d) A class that is used for encryption
Answer: a) A class that is used for pattern matching
Explanation: A case class is a special type of class in Scala that is primarily used for pattern matching. It is immutable by default, and it automatically generates implementations of useful methods such as equals(), hashCode(), and toString().
What is a singleton object in Scala?
a) An object that can only be instantiated once
b) An object that is instantiated multiple times
c) An object that can be extended by other classes
d) An object that can be instantiated as a regular class
Answer: a) An object that can only be instantiated once
Explanation: A singleton object is a special type of object in Scala that can only be instantiated once. It is often used to hold utility methods or provide global configuration settings.
What is the difference between a method and a function in Scala?
a) A method is an object-oriented concept, while a function is a functional programming concept.
b) A method is a block of code that is part of a class, while a function is a standalone block of code.
c) A method can take arguments and have a return type, while a function cannot take arguments or have a return type.
d) A method and a function are the same thing in Scala.
Answer: b) A method is a block of code that is part of a class, while a function is a standalone block of code.
Explanation: In Scala, a method is a block of code that is part of a class and can be called on an object of that class. A function, on the other hand, is a standalone block of code that can be called directly. Both can take arguments and have a return type.
What is tail recursion in Scala?
a) A type of recursion that uses a stack data structure
b) A type of recursion that uses a heap data structure
c) A type of recursion that eliminates the need for a stack frame on each recursive call
d) A type of recursion that requires an explicit base case
Answer: c) A type of recursion that eliminates the need for a stack frame on each recursive call
Explanation: Tail recursion is a type of recursion where the recursive call is the last operation in the function. This allows the Scala compiler to optimize the function so that it does not require a new stack frame on each recursive call, which can lead to improved performance and reduced memory usage.
What is a future in Scala?
a) A type of collection that is used for asynchronous programming
b) A type of function that is used for parallel programming
c) A type of object that is used for multithreading
d) A type of promise that is used for concurrent programming
Answer: d) A type of promise that is used for concurrent programming
Explanation: A future is a type of promise in Scala that represents a value that may not yet be available. It is commonly used in concurrent programming to allow one part of a program to wait for the result of a computation that is being performed in another part of the program.
What is pattern matching in Scala?
a) A way of testing for specific types of objects
b) A way of matching regular expressions
c) A way of testing for specific values in a collection
d) A way of testing for specific conditions in a program
Answer: a) A way of testing for specific types of objects
Explanation: Pattern matching is a powerful feature in Scala that allows you to test for specific types of objects and extract their values. It can be used in a variety of contexts, including matching on case classes, matching on collections, and matching on regular expressions.
What is a partial function in Scala?
a) A function that is only defined for some input values
b) A function that takes multiple arguments
c) A function that returns a collection
d) A function that can be used for parallel programming
Answer: a) A function that is only defined for some input values
Explanation: A partial function is a function in Scala that is not defined for all possible input values. Instead, it is defined only for a subset of the input values. When the function is called with an input value outside of its defined subset, a runtime error occurs.
What is the difference between val and var in Scala?
a) val is immutable, while var is mutable
b) val is a reference to an object, while var is a value
c) val is used for loop variables, while var is used for class variables
d) val and var are the same thing in Scala
Answer: a) val is immutable, while var is mutable
Explanation: In Scala, val is used to define a variable that cannot be reassigned once it has been initialized, while var is used to define a variable that can be reassigned. This makes val variables immutable and var variables mutable.
What is a higher-order function in Scala?
a) A function that takes another function as an argument or returns a function as its result
b) A function that has a return type of Unit
c) A function that takes multiple arguments
d) A function that cannot be used for parallel programming
Answer: a) A function that takes another function as an argument or returns a function as its result
Explanation: A higher-order function is a function in Scala that takes another function as an argument or returns a function as its result. This allows for powerful functional programming patterns, such as composing functions, passing functions as arguments to other functions, and returning functions as values.
What is an anonymous function in Scala?
a) A function that has no name and is defined inline
b) A function that has no arguments
c) A function that takes multiple arguments
d) A function that cannot be used with pattern matching
Answer: a) A function that has no name and is defined inline
Explanation: An anonymous function is a function in Scala that has no name and is defined inline. It is commonly used with higher-order functions to pass a function as an argument without having to define a separate named function.
What is currying in Scala?
a) A technique for transforming a function that takes multiple arguments into a series of functions that each take a single argument
b) A technique for transforming a function that takes a single argument into a function that takes multiple arguments
c) A technique for defining a function that returns a collection of functions
d) A technique for defining a function that takes a variable number of arguments
Answer: a) A technique for transforming a function that takes multiple arguments into a series of functions that each take a single argument
Explanation: Currying is a technique in functional programming for transforming a function that takes multiple arguments into a series of functions that each take a single argument. This allows for greater flexibility in composing functions and can lead to more concise and readable code.
What is a stream in Scala?
a) A lazy, potentially infinite sequence of elements
b) A collection of elements that are stored in memory
c) A collection of elements that are stored on disk
d) A collection of elements that are sorted in a specific order
Answer: a) A lazy, potentially infinite sequence of elements
Explanation: A stream is a data structure in Scala that represents a lazy, potentially infinite sequence of elements. It is evaluated lazily, meaning that elements are computed only when they are needed. This can lead to improved performance and reduced memory usage in certain cases.
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