How to Convert Scala Map into JSON String?

In this article, we will learn to convert a Scala Map into JSON String. We can convert Scala Map to JSON String using various libraries and custom conversion functions.

What is Scala Map?

In Scala, a Map is a collection of key-value pairs where each key is unique and maps to a corresponding value. It is similar to a dictionary in other programming languages. The Scala uses the immutable Map by default. If we want to use a mutable Map, then we need to import the import scala.collection.mutable.Map class explicitly.

Syntax:

val mapName: Map[KeyType, ValueType] = Map(key1 -> value1, key2 -> value2, …)

What is JSON String?

A JSON string is a textual representation of data in JSON (JavaScript Object Notation) format. It is commonly used for data interchange between a client and a server in web development and for storing structured data in a human-readable and machine-readable format.

Syntax:

val jsonString: String = “{\”key1\”: \”value1\”, \”key2\”: 2, \”key3\”: true}”

Converting Scala Map into JSON String

Below are the possible approaches to convert the scala map into JSON string.

Approach 1: Using Play JSON Library

1. In this approach, we are using the Play JSON library in Scala to convert a Scala Map into a JSON string.
2. First, we create a Scala Map with key-value pairs, and then we use Json.toJson and Json. stringify functions from Play JSON to convert the map into a JSON string.

Example:

The below example uses Play JSON Library to convert Scala Map into JSON String.

Scala

// Scala program to convert Scala Map into JSON String
import play.api.libs.json.Json

// Creating object
object GFG {

  // Main method
  def main(args: Array[String]): Unit = {

    // Creating a map
    val map = Map(
      "name" -> "GeeksforGeeks",
      "founder" -> "Sandeep Jain",
      "Place" -> "Noida"
    )

    // Converting Map into JSON String
    val res = Json.stringify(Json.toJson(map))

    // Printing Output
    println(res)
  }
}

Output:

Approach 2: Using Scala Function

1. In this approach, we define a custom Scala function conversionFn that takes a Scala Map as input and converts it into a JSON string using string interpolation and map operations.
2. The function iterates over the map’s key-value pairs, formats them as JSON key-value pairs, and then joins them together to form a valid JSON string.

Example:

In this example, we are using a Scala function to convert a Map into a JSON String.

Scala

// Scala program to convert Scala Map into JSON String

// Creating object
object GFG {

  // Function to convert Map into JSON String
  def conversionFn(map: Map[String, String]): String = {
    map
      .map { case (key, value) => s""""$key":"$value"""" }
      .mkString("{", ",", "}")
  }

  // Main Method
  def main(args: Array[String]): Unit = {

    // Creating a map
    val map = Map(
      "name" -> "GeeksforGeeks",
      "founder" -> "Sandeep Jain",
      "Place" -> "Noida"
    )

    // JSON String
    val res = conversionFn(map)

    // Printing Output
    println(res)
  }
}

Output:

Approach 3: Using Circle Library

1. In this approach, we use the circle library to convert a Scala Map into a JSON string.
2. The conversionFn function takes a Map[String, String] as input, uses asJson to convert it into a JSON structure, and then noSpaces to format it as a string without any additional spaces.

Example 3:

In this example, we use the Circe library’s asJson and noSpaces methods to convert a Scala Map into a JSON string.

Scala

// Scala program to convert Scala Map into JSON String

import io.circe._
import io.circe.syntax._

// Creating object
object MapToJson {

  // Map to JSON String Conversion
  def conversionFn(map: Map[String, String]): String = {
    map.asJson.noSpaces
  }

  // Main Method
  def main(args: Array[String]): Unit = {

    // Creating a map
    val map = Map(
      "name" -> "GeeksforGeeks",
      "founder" -> "Sandeep Jain",
      "Place" -> "Noida"
    )

    // JSON String
    val res = conversionFn(map)

    // Printing Output
    println(res)
  }
}

Output: