Kotlin Cheat Sheet

Hello World:

        
fun main() {
    println("Hello, World!")
}
        
    

Variables:

        
// Immutable variable
val name: String = "John Smith"

// Mutable variable
var age: Int = 25

// Type inference
val pi = 3.14159

// Nullable variable
var nullableValue: String? = null
        
    

Data Types:

        
// Numeric types
val number: Int = 10
val floatingPoint: Double = 3.14

// Boolean type
val boolean: Boolean = true

// Character type
val char: Char = 'A'

// String type
val text: String = "Hello"
        
    

Operators:

        
// Arithmetic operators
val sum = 5 + 3
val difference = 10 - 4
val division = 15 / 2
val remainder = 15 % 2
val product = 4 * 6

// Comparison operators
val isEqual = (5 == 5)
val isGreater = (10 > 5)
val isLessThanOrEqual = (15 <= 20)

// Logical operators
val logicalAnd = true && false
val logicalOr = true || false
val logicalNot = !true
        
    

Conditional Statements:

        
// If statement
if (condition) {
    // Code to execute if the condition is true
} else {
    // Code to execute if the condition is false
}

// When expression
val day = 3
when (day) {
    1 -> println("Monday")
    2 -> println("Tuesday")
    3 -> println("Wednesday")
    else -> println("Invalid day")
}
        
    

Loops:

        
// For loop
for (i in 1..5) {
    println(i)
}

// While loop
var count = 0
while (count < 5) {
    println(count)
    count++
}

// Do-While loop
var index = 0
do {
    println(index)
    index++
} while (index < 5)
        
    

Functions:

        
// Function declaration
fun functionName(parameters) {
    // Code to execute
}

// Function with return value
fun multiply(a: Int, b: Int): Int {
    val result = a * b
    return result
}

// Function call
functionName(arguments)
        
    

Classes:

        
// Class declaration
class MyClass {
    // Properties
    var name: String = ""
    var age: Int = 0

    // Member function
    fun greet() {
        println("Hello, my name is $name")
    }
}

// Creating an instance
val myObject = MyClass()

// Accessing class members
myObject.name = "John"
myObject.age = 25
myObject.greet()