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Scala Identifiers

In this tutorial, we will learn about the identifiers in Scala, their examples, rules to declare them and its types. By Shivang Yadav Last updated : April 02, 2023

What are Identifiers?

Identifiers in a programming language are the names given to a class, method, variable or object to identify them in the program.

Example

Here is a sample Scala code:

object myObject {
    def main(args: Array[String]) {
        var value1 = 54
        var value2 = 65
        
        println("The sum of two values is " + (value1 + value2))
    }
}

Output

The sum of two values is 119

All identifiers in this program are, myObject, main, args, value1, value2.

The declaration of these identifiers is based on certain rules. And programs violating these rules will return a compiler-Time error on compilation.

Rules to declare an identifier

1. You cannot use a Scala keyword as identifier in Scala. Example, class is not a valid identifier.
2. Reserved words cannot be used as identifiers in Scala. Example, $ cannot be an identifier.
3. There is no upper limit to the number of characters used in the identifier. WelcomeToScalaProgrammingLanguage is also a valid identifier.
4. An identifier cannot start with digits. Example, 2421Scala is not a valid identifier.
5. Scala identifiers are case-sensitive. Example, isgreater and isGreater are different identifiers.

Types of identifiers

In Scala, we have 4 different types of identifiers defined. They are:

1. Alphanumeric Identifiers
2. Operator Identifiers
3. Mixed Identifiers
4. Literal Identifiers

1) Alphanumeric Identifiers

As the name suggests, these identifiers are named using alphabets and numbers and underscore. As an identifier cannot start with a number, the start of an alphanumeric identifier is underscore (_) or a character followed by a number.

Example

Scala123, is12thDigit

Scala Example of Alphanumeric Identifiers

object myObject {
    def main(args: Array[String]) {
        var _value1 = 54
        var value_2 = 65
        
        println("The sum of two values is " + (_value1 + value_2))
    }
}

Output

The sum of two values is 119

2) Operator Identifiers

This type of identifier contains only operators i.e., they are a combination of one or more operators in Scala. The operators include '+', '#', '*', '<='.

Example

=== , +

Scala Example of Operator Identifiers

object myObject {
    def main(args: Array[String]) {
        var _value1 = 54
        var value_2 = 65
        
        println("The result after using '+' identifier is " + (_value1 + value_2))
    }
}

Output

The result after using '+' identifier is 119

3) Mixed Identifiers

As the name suggests, these types of identifiers are a mixture of the above stated two types of identifiers. it contains an alphanumeric identifier followed by an operator identifier with an underscore in between.

Example

avg_+, val_=

Scala Example of Mixed Identifiers

object myObject {
    def main(args: Array[String]) {
        var _value1 = 54
        var value_2 = 65
    
        var val_+ = _value1 + value_2
    
        println("The sum is " + (val_+))
    }
}

Output

The sum is 119

4) Literal Identifiers

A string literal used as an identifier in Scala is a literal identifier. These are strings enclosed inside ticks ('...').

Example

`scala`, `value`

Scala Example of Literal Identifiers

object myObject {
    def main(args: Array[String]) {
        var `firstValue` = 54
        var `secondValue` = 65
        
        var `result` = `firstValue` + `secondValue`
        
        println("The result of sum is " + (`result`))
    }
}

Output

The result of sum is 119

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