Kotlin Variables and Data Types

In Kotlin, one of the statically typed programming languages, understanding variables and data types is key to mastering the language. This guide will take you from the basics to the more advanced aspects of these crucial elements.

Deep Dive into Kotlin Variables

In Kotlin, variables are declared using val and var. The val keyword is used to declare a read-only (immutable) variable, while var declares a mutable variable.

val immutableVar: String = "I can't be changed"
var mutableVar: Int = 25

Once you declare a val variable, you can’t change its value, while you can change the value of a var variable:

mutableVar = 30  // This is perfectly valid
immutableVar = "Let's change!"  // Compilation error: Val cannot be reassigned

Kotlin’s Rich Palette of Data Types

Kotlin provides a rich set of built-in data types, including:

  • Numbers: Byte, Short, Int, Long, Float, Double
  • Characters: Char
  • Booleans: Boolean
  • Arrays
  • Strings

Here is a brief example demonstrating some of these types:

val myInt: Int = 10
val myLong: Long = 100L
val myFloat: Float = 100.00f
val myDouble: Double = 100.00
val myByte: Byte = 1
val myShort: Short = 1
val myBoolean: Boolean = true
val myChar: Char = 'a'
val myString: String = "Hello Kotlin"
val myArray: Array<Int> = arrayOf(1, 2, 3, 4, 5)

Embracing String Manipulation in Kotlin

Strings in Kotlin are arrays of characters. They are immutable and come with a rich API for manipulation.

val myString: String = "Hello Kotlin"
val len: Int = myString.length
val subString: String = myString.substring(0 until 5)

In this code, len will be 12, and subString will be Hello.


Mastering variables and data types is the first step towards becoming proficient in Kotlin. Practice these concepts, experiment with them, and remember, in the words of Sheryl Sandberg,

“Done is better than perfect.”

Happy Kotlin coding!