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Integer types

Learn Int, Long, Short and Byte types.

Integer types

In Kotlin, integers come in four types: Byte (8 bit), Short (16 bit), Int (32 bit) and Long (64 bit). Int is the most common; type inference picks Int in most cases.

Long is used for very large numbers (e.g., millisecond timestamps). Long literals are written with an L suffix: val big = 100L.

val a: Byte = 12        // -128..127
val b: Short = 1000     // -32768..32767
val c: Int = 100000     // ~±2 billion
val d: Long = 100L      // very large

Practice Try Long

At the top level, declare val timestamp: Long = 1700000000L. Inside fun main(), print with println(timestamp).

Sample solution

Main.kt
val timestamp: Long = 1700000000L

fun main() {
    println(timestamp)
}

Expected output

1700000000

Which type to choose?

In most cases Int is enough; its range of about ±2 billion covers most applications. For very large numbers (timestamps, large calculations) you use Long.

Byte and Short are used less; the memory saving is small on modern systems and they are promoted to Int in operations. Still, Byte is common when reading binary data.

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Which is the most common integer type?

  • Int Correct answer
  • Byte
  • Short
  • Long

Explanation: Int is the default integer type in most cases.

2 Long suffix

Question 
val big = 100____
Answer 
val big = 100L

Explanation: Long literals are written with the L suffix.

3 Integer types: match the terms

Term Meaning
Byte 8 bit
Short 16 bit
Int 32 bit
Long 64 bit

All lessons in Beginner

1 Kotlin basics

  1. What is Kotlin?
  2. Your first program
  3. The main function
  4. Comments
  5. String templates
  6. Summary - Kotlin basics

2 Variables

  1. val and var
  2. Type inference
  3. const
  4. lateinit
  5. by lazy
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. Boolean and Char
  4. String
  5. Any and Unit
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Elvis operator
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String templates
  3. String methods
  4. substring
  5. split and replace
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. if expression
  4. when
  5. when expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. Range
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Creating arrays
  2. Array access
  3. Array size
  4. Array loop
  5. Array methods
  6. Summary - Arrays

11 Lists

  1. Creating lists
  2. List operations
  3. List access
  4. List iteration
  5. List methods
  6. Summary - Lists

12 Maps and Sets

  1. Creating sets
  2. Set operations
  3. Creating maps
  4. Map operations
  5. Map iteration
  6. Summary - Maps and Sets

13 Functions

  1. Defining functions
  2. Return values
  3. Expression body
  4. Default parameters
  5. Named arguments
  6. Summary - Functions

14 Null safety

  1. Nullable types
  2. ?, !! and ?:
  3. let
  4. Null check
  5. lateinit
  6. Summary - Null safety

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string operations

  1. Regex
  2. matches and find
  3. replace
  4. StringBuilder
  5. trim and pad
  6. Summary - Advanced strings

17 Enums

  1. enum class
  2. Enum values
  3. Enum properties
  4. when with enum
  5. Enum and range
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. try expression
  5. Custom exceptions
  6. Summary - Exceptions

19 Class basics

  1. class
  2. Constructor
  3. Properties
  4. Methods
  5. this
  6. Summary - Class basics

20 Beginner final

  1. Project design
  2. Classes
  3. Collections
  4. Error handling
  5. Putting it together