➕ Kotlin – Operators: Arithmetic, Logical, Relational & More
🧲 Introduction – Why Learn Kotlin Operators?
Operators are symbols that perform computations, comparisons, and logic operations on variables and values. Kotlin supports a wide range of operators similar to Java but with added clarity and null-safety. Mastering Kotlin operators allows you to write efficient, readable, and expressive code.
🎯 In this guide, you’ll learn:
- All major categories of Kotlin operators
- Syntax and examples for arithmetic, logical, and relational operations
- How Kotlin handles null-safe operations and operator overloading
- Best practices for operator usage
🧮 Arithmetic Operators
Used to perform basic mathematical operations.
| Operator | Name | Example | Output |
|---|---|---|---|
+ | Addition | 10 + 5 | 15 |
- | Subtraction | 10 - 5 | 5 |
* | Multiplication | 10 * 5 | 50 |
/ | Division | 10 / 2 | 5 |
% | Modulus | 10 % 3 | 1 |
✨ Example:
val a = 12
val b = 4
println("Sum: ${a + b}, Product: ${a * b}")
✅ Output:
Sum: 16, Product: 48
⚖️ Relational (Comparison) Operators
Used to compare values. They return true or false.
| Operator | Description | Example | Output |
|---|---|---|---|
== | Equal to | 5 == 5 | true |
!= | Not equal to | 5 != 3 | true |
> | Greater than | 6 > 2 | true |
< | Less than | 2 < 5 | true |
>= | Greater than or equal | 3 >= 3 | true |
<= | Less than or equal | 2 <= 1 | false |
🔁 Assignment Operators
Used to assign and update values in variables.
| Operator | Description | Example | Equivalent To |
|---|---|---|---|
= | Assignment | a = 10 | – |
+= | Add and assign | a += 5 | a = a + 5 |
-= | Subtract and assign | a -= 3 | a = a - 3 |
*= | Multiply and assign | a *= 2 | a = a * 2 |
/= | Divide and assign | a /= 2 | a = a / 2 |
%= | Modulo and assign | a %= 3 | a = a % 3 |
⚙️ Unary Operators
Operate on a single operand.
| Operator | Meaning | Example |
|---|---|---|
+ | Unary plus | +a |
- | Unary minus | -a |
++ | Increment | a++ |
-- | Decrement | a-- |
! | Logical NOT | !true |
🤔 Logical Operators
Used to build compound boolean expressions.
| Operator | Description | Example | Result |
|---|---|---|---|
&& | Logical AND | true && false | false |
| ` | ` | Logical OR | |
! | Logical NOT | !true | false |
val age = 25
val isMember = true
if (age > 18 && isMember) {
println("Eligible")
}
✅ Output:
Eligible
🔎 Kotlin Identity & Equality Operators
| Operator | Description | Example |
|---|---|---|
== | Structural equality | a == b (content match) |
=== | Referential equality | a === b (same object) |
val str1 = "Hello"
val str2 = "Hello"
println(str1 == str2) // true
println(str1 === str2) // might be true (same reference in memory)
❔ Null-Safety Operators
Kotlin introduces special operators for handling nulls safely.
| Operator | Name | Example | Purpose |
|---|---|---|---|
?. | Safe call | name?.length | Avoids NullPointerException |
?: | Elvis operator | name ?: "Guest" | Default value if null |
!! | Not-null assert | name!! | Throws NPE if null |
💡 Operator Overloading in Kotlin
Kotlin allows custom operator overloading for classes using predefined keywords.
✅ Example:
data class Point(val x: Int, val y: Int) {
operator fun plus(other: Point) = Point(x + other.x, y + other.y)
}
val p1 = Point(2, 3)
val p2 = Point(4, 1)
println(p1 + p2) // Output: Point(x=6, y=4)
📌 Summary – Recap & Next Steps
Kotlin offers a rich set of operators that make arithmetic, logic, and comparison tasks intuitive and expressive. It also introduces null-safe operators and operator overloading, making Kotlin highly flexible and safe.
🔍 Key Takeaways:
- Use arithmetic, logical, and relational operators like in Java.
- Kotlin supports structural (
==) and referential (===) equality. - Use null-safety operators to avoid
NullPointerExceptions. - Operator overloading enables expressive custom logic in classes.
⚙️ Practical Use:
Operators are critical in every Kotlin application—from simple calculations to complex conditions in Android, backend services, and business logic.
❓ FAQs – Kotlin Operators
❓ What’s the difference between == and === in Kotlin?
✅ == checks value equality, while === checks reference equality (if two variables point to the same object).
❓ How does Kotlin handle nulls with operators?
✅ Use the safe call operator ?., the Elvis operator ?:, or !! for asserting non-null.
❓ Can I overload operators in Kotlin?
✅ Yes. Kotlin allows operator overloading by defining functions with the operator keyword in classes.
❓ Does Kotlin support all Java-style operators?
✅ Yes, including arithmetic, comparison, assignment, and logical operators—plus Kotlin adds null-safety operators.
❓ Can I use ++ and -- in Kotlin like in Java?
✅ Yes. Kotlin supports a++, --b, etc., for increment/decrement operations.
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