Understanding Data Types in Kotlin

Think of data types as different kinds of containers for your information. Just like you use different boxes for different items (shoebox for shoes, food containers for meals), Kotlin uses different data types for different kinds of data!

📊 What Are Data Types?

Data types tell Kotlin what kind of information you're storing. This helps Kotlin understand how to handle your data and what you can do with it.

Real-Life Example:

Imagine you're organizing your room:

✅ Numbers - like your age or item counts (use Int, Double)
✅ Text - like names or messages (use String)
✅ True/False - like yes/no questions (use Boolean)
✅ Single Characters - like grades or initials (use Char)

🔢 Number Types - For Counting and Measuring

📏 Whole Numbers (No Decimals)

Int - The All-Purpose Counter

Perfect for most counting situations

val age = 25
val itemsInCart = 3
val numberOfStudents = 30

Long - For Really Big Numbers

Use when numbers get very large

val worldPopulation = 8000000000L
val bigNumber = 1234567890123L

📐 Decimal Numbers (With Fractions)

Double - Precise Measurements

Great for prices, measurements, percentages

val price = 19.99
val temperature = 98.6
val percentage = 85.5

Float - Lighter Decimal Numbers

Less precise but uses less memory

val weight = 68.5F
val distance = 3.14F

📝 Text Types - For Words and Messages

String - For Text and Sentences

Anything that involves words or messages

val name = "John Doe"
val message = "Hello, welcome to Kotlin!"
val email = "[email protected]"

Char - Single Characters

For when you only need one letter or symbol

val grade = 'A'
val firstInitial = 'J'
val symbol = '$'

✅❌ Boolean - For Yes/No Decisions

The simplest type - only two possible values: true or false

Boolean - Decision Maker

Perfect for conditions and switches

val isSunny = true
val hasPermission = false
val isLoggedIn = true
val isEmpty = false

🎯 Quick Guide: Which Type to Use?

👤 Storing a person's name?

String - because names are text

val userName = "Alice"

🎂 Storing someone's age?

Int - because age is a whole number

val userAge = 30

💰 Storing a product price?

Double - because prices often have decimals

val productPrice = 29.99

🔔 Tracking if a user is online?

Boolean - because it's either true or false

val isOnline = true

🧪 Let's Practice Together!

For each situation, choose the right data type:

1. Storing a person's email address:

val email: String = "[email protected]"

Why? Email addresses are text, so we use String

2. Tracking the number of likes on a post:

val likes: Int = 150

Why? Likes are whole numbers, so we use Int

3. Storing a product rating (like 4.5 stars):

val rating: Double = 4.5

Why? Ratings often have decimals, so we use Double

4. Remembering if a user is premium:

val isPremium: Boolean = true

Why? This is a yes/no question, so we use Boolean

📝 Simple Rules to Remember

For Whole Numbers

Int - regular numbers

Long - really big numbers

For Decimal Numbers

Double - precise decimals

Float - lighter decimals

For Text

String - words & sentences

Char - single characters

For True/False

Boolean - yes/no decisions

Only true or false

💡 Pro Tip: Kotlin is Smart!

Most of the time, Kotlin can guess the type automatically:

val name = "Alice"        // Kotlin knows this is String
val age = 25 // Kotlin knows this is Int
val price = 19.99 // Kotlin knows this is Double
val isActive = true // Kotlin knows this is Boolean

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