Kotlin Basic Syntax

Welcome to the world of Kotlin programming! In this blog, we will cover some basic syntax elements in Kotlin.

Variables:

Variables in Kotlin can be declared using the var keyword for mutable variables and the val keyword for immutable variables. For example:

var x = 5 // mutable variable
val y = 10 // immutable variable

You can also specify the data type of a variable using the : operator. For example:

var x: Int = 5
val y: Double = 3.14

Creating classes:

In Kotlin, you can create classes using the class keyword. For example:

class MyClass {
  val x: Int = 10
  fun printX() {
    println(x)
  }
}

You can create an instance of a class using the new keyword or by calling the class name as a function. For example:

val obj1 = MyClass()
val obj2 = MyClass

Comments:

In Kotlin, you can use single-line comments by starting a line with //. For example:

// This is a single-line comment

You can also use multi-line comments by enclosing them in /* and */. For example:

/*
This is a
multi-line
comment
*/

String:

In Kotlin, a string is a sequence of characters represented by the String data type. You can create a string using double quotes (") or triple quotes ("""). For example:

val str1 = "Hello, Kotlin"
val str2 = """Hello,
Kotlin"""

Triple quotes are useful for creating multi-line strings. They preserve the line breaks and whitespace in the string.

Conditional expressions

fun main() {
  val x = 10
  if (x > 5) {
    println("x is greater than 5")
  } else {
    println("x is less than or equal to 5")
  }
}

while loop:

 while (count < 5) {
        println(count)
        count++
    }

when:

val x = 3
    when (x) {
        1 -> println("x is 1")
        2 -> println("x is 2")
        3 -> println("x is 3")
        else -> println("x is something else")
    }

Ranges:

val x = 3
val y = 10

// Check if x is in the range 1 to 10 (inclusive)
if (x in 1..10) {
    println("x is between 1 and 10")
}

// Check if y is outside the range 1 to 10 (exclusive)
if (y !in 1 until 10) {
    println("y is not between 1 and 10")
}

Collections:

val numbers = listOf(1, 2, 3, 4, 5)

val firstItem = numbers[0] // firstItem is 1
val lastItem = numbers[numbers.size - 1] // lastItem is 5

for (number in numbers) {
    println(number)
}

Nullable:

In Kotlin, a nullable type is a type that can hold either a value or null. You can declare a nullable type by adding a ? after the type name. For example:

val s: String? = null
val length = s?.length // length is null

val x = "hello"
if (x is String) {
  println("x is a string")
}