🎯

Kotlin Essentials

42 cards · 🇺🇸 English

Core Kotlin syntax, null safety, and Android-friendly language features.

Study all 42 cards for free

Flashcards, quizzes, pixel-art games and a daily review that remembers for you.

Study this deck free

Try the first 10 cards

1 / 10

Question

Kotlin

Knew itLearning

Tap the card for the answer · swipe right if you knew it, left if not

Already have an account? Sign in

Cards

1Kotlin
A cross-platform, statically typed, general-purpose high-level programming language with type inference, designed to interoperate fully with Java
2Origin of the name 'Kotlin'
It's named after Kotlin Island, a Russian island in the Gulf of Finland near Saint Petersburg
3What platforms can Kotlin target?
JVM, Android, iOS, JavaScript, WebAssembly, and native code via LLVM (Kotlin/Native)
4Are semicolons required in Kotlin?
No, semicolons are optional as statement terminators; in most cases a newline is sufficient
5Where do data types appear in Kotlin variable declarations?
After the variable name, separated by a colon (similar to TypeScript, Pascal, and Rust)
6What keyword declares a mutable variable in Kotlin?
var
7What keyword declares an immutable variable in Kotlin?
val
8Are Kotlin classes open for inheritance by default?
No, all classes are public and final (non-inheritable) by default
9What keyword is needed to make a Kotlin class inheritable?
open
10Are abstract classes in Kotlin open by default?
Yes, abstract classes are open by default
11Default visibility modifier for Kotlin classes and members
public
12Four visibility modifiers in Kotlin
public, internal, protected, and private
13'internal' visibility modifier
Visible within a module
14Entry point function name in a Kotlin program
main
15Does Kotlin's main function require parameters?
No, parameters are optional since Kotlin 1.3
16What symbol is used for string interpolation in Kotlin?
$ (dollar sign), e.g., "Hello, $name!"
17Extension functions in Kotlin
Functions that can be added to any class without creating a derived class, appearing exactly like a function of the class
18How many scope functions does Kotlin have, and what are they?
Five: let, run, with, apply, and also
19What operator unpacks an array's contents as individual arguments in Kotlin?
The spread operator asterisk (*)
20Destructuring declarations in Kotlin
A feature that decomposes an object into multiple variables at once, e.g., for ((key, value) in map)
21Can you declare local functions inside other functions in Kotlin?
Yes, Kotlin allows local functions to be declared inside of other functions or methods
22Sealed class in Kotlin
A class that restricts subclass hierarchies, where all subclasses must be defined at compile time
23Data class in Kotlin
A class whose primary purpose is storing data, with automatically generated equals, hashCode, and toString methods
24How does Kotlin handle nullable types?
By making a distinction between nullable and non-nullable data types, with nullable objects declared with a '?' postfix
25Safe navigation operator in Kotlin
?. - used to safely access a method or property of a possibly null object (returns null if the object is null)
26Elvis operator in Kotlin
?: - a binary operator that returns the first operand if non-null, else the second operand
27Does Kotlin support higher-order functions?
Yes, Kotlin provides support for higher-order functions and anonymous functions (lambdas)
28How are lambda expressions declared in Kotlin?
Using braces { }, with parameters declared within the braces followed by the -> operator
29Three main compile targets for Kotlin code
Kotlin/JVM (Java bytecode), Kotlin/JS (JavaScript), and Kotlin/Native (native code via LLVM)
30What Java bytecode version does the Kotlin/JVM compiler produce by default?
Java 8 compatible bytecode