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Comparison operators

Learn to compare values with ==, !=, <, >, <= and >=.

Comparison operators

Comparison operators compare two values and return a Boolean: == (equal), != (not equal), < (less than), > (greater than), <= (less or equal), >= (greater or equal).

These operators are commonly used in if conditions and loop conditions.

println(5 == 5)   // true
println(3 < 2)    // false
println(10 >= 10) // true

Practice Try comparison

Write a fun main(). Declare val a = 7 and val b = 10. Compare with println(a < b).

Sample solution

Main.kt
fun main() {
    val a = 7
    val b = 10
    println(a < b)
}

Expected output

true

== vs ===

In Kotlin == checks structural equality (is the content the same). For reference equality (is it the same object) use ===.

For simple types (Int, String) == is enough; it does a content comparison. For objects, == actually calls the equals() method. So you can safely use == to check whether two separate lists hold the same content.

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Comparison operators: match the terms

Term Meaning
== Equal
!= Not equal
&lt; Less than
&gt;= Greater or equal

2 What does `3 < 2` return?

  • true
  • false Correct answer
  • 3
  • It throws an error

Explanation: 3 is not less than 2, so it returns false.

3 Comparison operators: fill in the missing part

Question 
val same = (5 ____ 5)
println(same)  // true
Answer 
val same = (5 == 5)
println(same)  // true

Explanation: Use == for equality.

All lessons in Beginner

1 Kotlin basics

  1. What is Kotlin?
  2. Your first program
  3. The main function
  4. Comments
  5. String templates
  6. Summary - Kotlin basics

2 Variables

  1. val and var
  2. Type inference
  3. const
  4. lateinit
  5. by lazy
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. Boolean and Char
  4. String
  5. Any and Unit
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Elvis operator
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String templates
  3. String methods
  4. substring
  5. split and replace
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. if expression
  4. when
  5. when expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. Range
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Creating arrays
  2. Array access
  3. Array size
  4. Array loop
  5. Array methods
  6. Summary - Arrays

11 Lists

  1. Creating lists
  2. List operations
  3. List access
  4. List iteration
  5. List methods
  6. Summary - Lists

12 Maps and Sets

  1. Creating sets
  2. Set operations
  3. Creating maps
  4. Map operations
  5. Map iteration
  6. Summary - Maps and Sets

13 Functions

  1. Defining functions
  2. Return values
  3. Expression body
  4. Default parameters
  5. Named arguments
  6. Summary - Functions

14 Null safety

  1. Nullable types
  2. ?, !! and ?:
  3. let
  4. Null check
  5. lateinit
  6. Summary - Null safety

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string operations

  1. Regex
  2. matches and find
  3. replace
  4. StringBuilder
  5. trim and pad
  6. Summary - Advanced strings

17 Enums

  1. enum class
  2. Enum values
  3. Enum properties
  4. when with enum
  5. Enum and range
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. try expression
  5. Custom exceptions
  6. Summary - Exceptions

19 Class basics

  1. class
  2. Constructor
  3. Properties
  4. Methods
  5. this
  6. Summary - Class basics

20 Beginner final

  1. Project design
  2. Classes
  3. Collections
  4. Error handling
  5. Putting it together