Scala Conditional Expressions

Scala has similar conditional expressions as available in other programming languages.

1. If Statement

The statement inside the if block will only execute when the expression is true.

Syntax: 

if(expression) { // statements }

Note : In Scala, adding a semicolon(;) at the end of statements is optional and generally avoided, unlike Java .

Example : 

val color = "RED"

if (color == "BLUE") {
  println("Hey! This is Red Color")
}

println("Hey i skipped the if condition!")

Output : 

val color: String = RED

Hey i skipped the if condition!

2. If else Statement

In the if-else statement, either if or else will execute based on the result of the expression. If the expression is true, then the statement inside the if block will execute; otherwise, statements inside the else block will execute.

Syntax : 

If (expression) {
   //Statement or statements
} else {
  //statement or statements
}

Example : 

val age =17

if (age>18) {
 println("Candidate is eligible for voting")

} else {
  println("Candidate is not eligible for  voting")
}

Output : 

val age: Int = 17
Candidate is not eligible for  voting

3. If else ladder

This conditional expression is used when we need to provide multiple related conditions, and one of them will execute to provide the result.

Syntax: 

If (expression) {
   // statements
} else if(expression) {
   //statements
} else {
   // statements
}

Example: 

val marks = 75

val result = if (marks < 40) {
  "The student has failed"
} else if (marks < 50) {
  "Student has scored Grade D"
} else if (marks < 60) {
  "Student has scored Grade C"
} else if (marks < 75) {
  "Student has scored Grade B"
} else {
  "Student has scored Grade A"
}

Output: 

val marks: Int = 75
val result: String = Student has scored Grade A

4. Nested If else

This expression is used when one if-else is needed inside another if-else block. It is said to be nested if-else.

Example: 

val number1 = 2
val number2 = 3
val number3 = 2

if(number1 == number2) {

  if (number1 == number3) {
    "All three numbers are equal"
  
   } 
   else {
    "Numbers are unequal"
  }

}
else {
  "Numbers are unequal"
}

Output: 

val number1: Int = 2
val number2: Int = 3
val number3: Int = 2
val res3: String = Numbers are unequal

Another example: 

val marks = 175

val result = if (marks >= 0 && marks <= 100) {

    if (marks < 40) {
      "The student has failed"
    } else if (marks < 50) {
      "Student has scored Grade D"
    } else if (marks < 60) {
      "Student has scored Grade C"
    } else if (marks < 75) {
      "Student has scored Grade B"
    } else {
      "Student has scored Grade A"
    }

  } else
    "Invalid marks"

Output: 

val marks: Int = 175
val result: String = Invalid marks
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