Boolean type and logical operators in Kotlin

Introduction

Boolean type helps us store true or false values. Logical operators let us combine or change these true/false values to make decisions.

Checking if a light switch is on or off

Deciding if a user can log in based on username and password

Determining if a number is both positive and even

Checking if a door is locked or if an alarm is active

Combining multiple conditions to control game actions

Syntax

Kotlin

val isTrue: Boolean = true
val isFalse: Boolean = false

// Logical operators
val andResult = true && false  // AND
val orResult = true || false   // OR
val notResult = !true          // NOT

Boolean values are either true or false.

Logical operators combine Boolean values: && means both must be true, || means at least one is true, ! flips true to false and vice versa.

Examples

AND operator returns true only if both sides are true.

Kotlin

val a = true
val b = false
val c = a && b  // false because both are not true

OR operator returns true if at least one side is true.

Kotlin

val a = true
val b = false
val c = a || b  // true because one side is true

NOT operator flips true to false and false to true.

Kotlin

val a = true
val b = !a  // false because NOT flips the value

Sample Program

This program uses Boolean values and logical operators to decide if we should take an umbrella and if we can go outside.

Kotlin

fun main() {
    val isRaining = true
    val haveUmbrella = false

    // Should we take an umbrella?
    val takeUmbrella = isRaining && haveUmbrella
    println("Take umbrella: $takeUmbrella")

    // Should we go outside?
    val canGoOutside = !isRaining || haveUmbrella
    println("Can go outside: $canGoOutside")
}

Important Notes

Remember, && needs both sides true to return true.

|| returns true if any side is true.

! flips the Boolean value.

Summary

Boolean type stores true or false.

Use && for AND, || for OR, and ! for NOT.

Logical operators help make decisions by combining true/false values.