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Kotlin Snippets

These examples show some of the key commands and syntax of the Kotlin language.

See the Kotlin language documentation for information about the full language.

Area	Notes
Console Output	Showing messages on the console
Console Input	Getting user input from the console
Numbers	Defining and using numbers
Booleans	Using true / false values
Strings	Creating and working with text
Characters	Using individual characters
Escaped Characters	Using special characters
Variables	Creating and using variables to store data
Collections	Creating and using lists/sets of data
Arithmetic Operators	Mathmatical operations such as adding
Boolean/Logical Operators	Logical operations such as AND, OR
Branching / Decisions	Allowing a program to make choices
Loops / Iteration	Repeating sections of a program

Numbers

Numeric data types can be used to store both integer and real (fractional) values. By default, whole numbers are type Int and real/decimal numbers are type Double, however other types are available: Byte, Long and Float are common.

See the Kotlin docs for the full list and details of what values can be held by each type.

val age = 18                    // Int by default
val cost = 12345                // Int by default
val profit = 123456789000       // Long due to large value
val height = 1.85               // Double by default

Numeric types can be explicit:

val age: Byte = 18              // Byte due to given type
val cost: Long = 12345          // Long due to given type
val cost = 12345L               // Long due to 'L'
val height = 1.85f              // Float due to 'f'

Other ways of specifying values:

val profit = 123_456_789_000    // Underscores for readability
val distance = 1.2345e10        // Scientific notation
val code = 0x0FFF               // Hexadecimal value via '0x...'
val code = 0b01101110           // Binary value via '0b...'

Numbers can be manipulated using arithmetic operators:

val cost = 1234
val taxRate = 0.175
val finalCost = cost + (cost * taxRate)

Booleans

Boolean data types can be just one of two values: true or false.

var isUser = true
var isLoggedIn = true
var isManager = true
var isAdmin = false

Booleans can be combined using boolean operators:

if (isUser && isLoggedIn) {
    if (isManager || isAdmin) {
        ...
    }
}

Strings

Strings are collections of characters, defined using double quotation marks: "Hello!".

See the Kotlin docs for full details on how strings can be used and manipulated.

val name = "Jimmy Pickles"
val phone = "022 123 456"
val message = "Hello, World!"

Strings can contain escaped characters:

val info = "Line one\nLineTwo\nLineThree"

Strings can be concatenated (joined) using the + operator:

val forename = "Jimmy"
val surname = "Pickles"
val fullName = forename + " " + surname     // Jimmy Pickles

Variables can be included within strings using string templates:

val forename = "Jimmy"
val surname = "Pickles"
val greeting = "Hello, $forename $surname!"  // Hello, Jimmy Pickles!

Characters

Characters are individually defined using single quotation marks: 'A'

val initial = 'J'
val prompt = '>'
val digit = '9'

Escaped Characters

Escaped characters are defined with a leading slash \ and are used within strings where the literal value can’t be used: \n (new line), \' (single quote), \" (double quote), \\ (backslash) and \$ (dollar sign). The full list is here.

println("I shouted \"Hello!\" to her.\nThen I gave her a gift of \$200.")

would result in:

I shouted "Hello!" to her.
Then I gave her a gift of $200.

Unicode characters can be used via hex escape sequences:

println("Here is a kitty: \u0x1f63a")

would result in

Here is a kitty: 😺