Kotlin Data Types
Kotlin Data Types – Simplified & Fresh!
In Kotlin, every piece of data has a type — it tells Kotlin what kind of data you’re dealing with.
Kotlin usually figures out the type by looking at the value. But you can also declare it directly if needed.
Basic Examples
val number = 10 // Kotlin knows it's an Int val price = 10.99 // This becomes a Double Val grade = 'A' // A single character → Char val isActive = false // Boolean type val greeting = "Hey!" // Text → String
You can also mention the type clearly like this:
val number: Int = 10 val price: Double = 10.99 val grade: Char = 'A' val isActive: Boolean = false Val greeting: String = "Hey!"
Number Types
Kotlin splits numbers into two main families:
Whole Numbers (No Decimals)
| Type | Range | Example |
|---|---|---|
| Byte | -128 to 127 | val a: Byte = 100 |
| Short | -32,768 to 32,767 | val b: Short = 5000 |
| Int | -2B to +2B | val c: Int = 100000 |
| Long | Massive values (ends with L) | val d: Long = 15000000000L |
If the value is huge, use Long.
Decimals (Numbers With Points)
Used when you need to deal with fractions or real-world values.
| Type | Precision | Example |
|---|---|---|
| Float | 6–7 digits | val pi: Float = 3.14F |
| Double | ~15 digits | val value: Double = 9.999 |
Always add F to the end of a Float.
Scientific Notation
Yes, Kotlin supports scientific formats too!
val bigFloat: Float = 6E2F // 600.0 Val hugeDouble: Double = 1.2E4 // 12000.0
Boolean Type
This type only knows two answers: yes or no.
val isOnline: Boolean = true Val isDarkMode: Boolean = false
Great for decisions, conditions, and flags.
Character Type
This type stores a single letter or symbol. You must wrap it in single quotes.
val letter: Char = 'K'
You can’t use numbers like 66 to represent letters — unlike Java, Kotlin doesn’t accept ASCII values.
Strings – Text Storage
A String holds words, sentences, or anything inside double quotes.
val message: String = "Welcome to Kotlin"
A String is basically a bunch of characters put together.
Arrays – Storing Many Values
Arrays allow you to store several items in one variable.
val colors = arrayOf("Red", "Blue", "Green")
Type Conversion – Changing Types
Kotlin doesn’t convert types automatically like Java. You need to manually convert values with special functions:
This is the correct way:
val count: Int = 5 val bigCount: Long = count.toLong()
Conversion Functions:
- toByte()
- toShort()
- toInt()
- toLong()
- toFloat()
- toDouble()
- toChar()
Recap – Quick View
| Type Group | Types | Purpose |
|---|---|---|
| Whole #s | Byte, Short, Int, Long | Counted values |
| Decimal #s | Float, Double | Prices, measurements |
| Text | Char, String | Characters & words |
| Logic | Boolean | True/False conditions |
| Multiple | Array | Group of items together |
Prefer Learning by Watching?
Watch these YouTube tutorials to understand KOTLIN Tutorial visually:
What You'll Learn:
- 📌 Kotlin Variables and Data Types. Kotlin Basic Syntaxes #3.2
- 📌 Kotlin Tutorial for Beginners - Kotlin Data Types