Scala StringContext Class

Scala | StringContext Class: In this tutorial, we will learn about the StringContext Class in Scala and examples of the StringContext Class.
Submitted by Shivang Yadav, on July 13, 2020

StringContext

The stringContext class in Scala is used to support string interpolation. The class extends the product with serializable. And has linear supertypes Serializable, java.io.Serializable, Product, Equals, AnyRef, Any.

The class has the following members that support string interpolation:

Formatted string interpolater: macro def f[A >: Any] (argument : A*) : String
Raw string interpolater: def raw(argument: Any*) : String
Simple string interpolater: def s(argument: Any* ): String

All three functions are used for string interpolation. And are used to add variables between the formatted strings.

Let's see each of the methods in action to interpolate strings.

Formatted string interpolater

It is used to add the given arguments (variables/ expressions) in between the string. At the specified positions.

Syntax:

macro def f[A >: Any] (argument : A*) : String

Arguments: It can take any number of arguments that will be inserted in the string. The variable after $ is arguments.

Return Type: It returns a string which is interpolated string.

Example:

object MyClass {
    def strPrint(proglang : String , year : Int){
        printf(f"$proglang was released in the year $year.\n")
    }
        
    def main(args: Array[String]) {
        strPrint("Scala", 2004)
        strPrint("JavaScript", 1995)
    }
}

Output:

Scala was released in the year 2004.
JavaScript was released in the year 1995.

In the above code, we have created a function strPrint() which accepts two arguments a string and an integer value. And interpolate them to a string in the following way:
proglang + " was released in the year " + year + "." and prints the result based on the arguments.

2) Raw string interpolator

It is used to insert the given arguments (variables) in their places defined in the string.

Syntax:

def raw(argument: Any*) : String

Arguments: It can take any number of arguments that will be inserted in the string. The variable after $ is arguments.

Return Type: It returns a string which is interpolated string.

Example:

object MyClass {
    def RawStrInterpolator(employee : String , salary : Int){
        println(StringContext(""," gets a salary of Rs.", ".").raw(employee , salary))
    }
        
    def main(args: Array[String]) {
        RawStrInterpolator("Sudhir", 175000)
        RawStrInterpolator("Ramesh", 50000)
    }
}

Output:

Sudhir gets a salary of Rs.175000.
Ramesh gets a salary of Rs.50000.

In the above code, we have created a method RawStrInterpolator() that demonstrates the functioning of Raw String Interpolator. The method accepts two arguments named employee and salary and interpolates then to the string using the raw method. The output of the interpolated string is of the form :
employee + " gets a salary of Rs." + salary + ".". And then prints the output based on the arguments.

3) Simple string interpolator

This method is used to add the given arguments in their places in the given string.

Syntax:

def s(argument: Any*) : String

Arguments: It can take any number of arguments that will be inserted in the string. The variable after $ is arguments.

Return Type: It returns a string which is interpolated string.

Example:

object MyClass {
    def simpleStrInterpolator(principal : Int , rate : Int){
        println(s"The interest on $principal at the rate of $rate for 1 year is ${(principal*rate*1)/100 }")
    }
        
    def main(args: Array[String]) {
        simpleStrInterpolator(175000, 8)
        simpleStrInterpolator(50000, 10)
    }
}

Output:

The interest on 175000 at the rate of 8 for 1 year is 14000
The interest on 50000 at the rate of 10 for 1 year is 5000

In the above code, we have created a function simpleStrInterpolator() which interpolates the string using s method. We have passed two arguments to the string which are principal and rate. The output of the interpolated string is of the form:
"The interest on" + principal + "at the rate of" + rate + "for 1 year is" + {(principal*rate*1)/100 }