Conditional Statements in Scala: A Complete Guide

Introduction

Conditional statements are fundamental in programming, allowing developers to control the flow of execution based on conditions. In Scala, the primary conditional constructs include if-else and match, which provide powerful ways to handle decision-making in code.

In this guide, we will explore conditional statements in Scala, their syntax, use cases, and best practices for writing clean and efficient code.

If-Else Statements in Scala

The if-else statement in Scala works similarly to other programming languages, evaluating a condition and executing the corresponding block of code.

Basic If-Else Syntax

object IfElseExample {
  def main(args: Array[String]): Unit = {
    val num = 10

    if (num > 0) {
      println("Positive number")
    } else {
      println("Non-positive number")
    }
  }
}

Output:

Positive number

If-Else If Ladder

val age = 18

if (age < 13) {
  println("Child")
} else if (age < 20) {
  println("Teenager")
} else {
  println("Adult")
}

Single-Line If Statement

Scala allows writing concise if statements without curly braces for single-line expressions:

if (age >= 18) println("Eligible to vote")

If-Else as an Expression

In Scala, if-else can return a value, making it more functional:

val result = if (num % 2 == 0) "Even" else "Odd"
println(result)

Match Expression in Scala

The match expression in Scala is an advanced alternative to if-else statements, similar to switch-case in other languages but more powerful.

Basic Match Syntax

val day = "Monday"
day match {
  case "Monday" => println("Start of the week")
  case "Friday" => println("Weekend is near")
  case _ => println("A regular day")
}

Match Expression with Return Value

Scala's match can return a value, making it more expressive:

val numType = num match {
  case n if n > 0 => "Positive"
  case 0 => "Zero"
  case _ => "Negative"
}
println(numType)

Match with Multiple Conditions

val vowelCheck = 'a' match {
  case 'a' | 'e' | 'i' | 'o' | 'u' => "Vowel"
  case _ => "Consonant"
}
println(vowelCheck)

Pattern Matching with Case Classes

case class Person(name: String, age: Int)
val person = Person("John", 25)

person match {
  case Person("John", 25) => println("Matched John")
  case Person(_, age) if age > 18 => println("Adult")
  case _ => println("Unknown Person")
}

When to Use If-Else vs. Match

Best Practices for Using Conditional Statements

1. Prefer match for multiple conditions – It is more readable and concise.
2. Use expressions instead of side effects – Return values from if-else or match instead of just printing.
3. Avoid deep nesting – Refactor complex logic into functions.
4. Use pattern matching for structured data – Makes code more robust and scalable.

Conclusion

Conditional statements in Scala provide flexibility and power through if-else and match. While if-else is suitable for simple conditions, match is preferred for complex decision-making and pattern matching.

By mastering these concepts, Scala developers can write clean, efficient, and maintainable code. Experiment with these constructs in your projects to leverage their full potential!