How to Format Strings in Scala

In this tutorial, we will discuss the string formatting procedure in Scala.

A string is a sequence of characters and is an immutable data type as in Java. We can create a string using string literals and append (join) using the plus (+) operator.

After creating it, Scala provides several ways to format a string to make it more readable. In Scala, we can format the string using string interpolation.

Creating a String in Scala

We create a string by assigning it to a variable and printing it.

object MyClass {
    def main(args: Array[String]) {
        var str = "Scala String"
        print(str)
    }
}

Output:

Scala String

As we have already mentioned, a string is immutable, and modifying the string does not alter the original string. Here, we created a string and then modified it by adding a new string using the plus (+) operator.

object MyClass {
    def main(args: Array[String]) {
        var str = "Scala String"
        "Hello "+str
        print(str)
    }
}

Output:

Scala String

String Formatting Using the s Placeholder in Scala

String interpolation is the process of formatting string in Scala. It provides some keys/placeholders that we can use with the string.

We used the s placeholder with the string that allows to use of variables with the string and replace with the values during execution.

object MyClass {
    def main(args: Array[String]) {
        var a = 10
        var b = 20.5;
        println(s"value of a = $a")
        println(s"value of b = $b")
    }
}

Output:

value of a = 10
value of b = 20.5

String Formatting Using the f Placeholder in Scala

We used the f with the string that allows to use of variables with the string and replace with the values during execution. The variable must include $ with the variable.

object MyClass {
    def main(args: Array[String]) {
        var a = 10
        var b = 20.5;
        println(f"value of a = $a")
        println(f"value of b = $b")
    }
}

Output:

value of a = 10
value of b = 20.5

String Formatting Using the raw Placeholder in Scala

If you want to print a raw string that includes all the formatting symbols, then use the raw placeholder as a prefix with the string. You can clearly understand the difference between printing strings with or without this placeholder in the output.

object MyClass {
    def main(args: Array[String]) {
        var a = "Scala \tstring \n formatting"
        var b = raw"Scala \tstring \n formatting"
        println(a)
        println(b)
    }
}

Output:

Scala string
 formatting
Scala \tstring \n formatting

String Formatting Using the format() Function in Scala

Scala provides a string function format() which acts as a print() function of C. It is used to create a formatted string that you can use anywhere in your code.

object MyClass {
    def main(args: Array[String]) {
        var a = 1
        var b = 10
        var str1 = "This is %s string".format(a)
        var str2 = "This is %s string".format(b)
        println(str1)
        println(str2)
    }
}

Output:

This is 1 string
This is 10 string