How to Convert a Java Map to a Scala Map with Set Values

How can I convert a Java Map with Collection values to a Scala Map with Set values?

import scala.jdk.CollectionConverters._
import scala.collection.immutable.Set

val javaMap: java.util.Map[SomeObject, java.util.Collection[OtherObject]] = ???
val scalaMap: Map[SomeObject, Set[OtherObject]] = 
  javaMap.asScala.toMap.map { case (key, value) => 
    key -> Set(value.asScala.toSeq: _*)
  }

Converting a Java Map with Collection values into a Scala Map that requires Set values involves using Scala's collection conversion utilities. This process ensures that each value in the Map is transformed from a Java Collection to a Scala Set, preserving the uniqueness of elements.

import scala.jdk.CollectionConverters._

val javaMap: java.util.Map[SomeObject, java.util.Collection[OtherObject]] = ???
val scalaMap: Map[SomeObject, Set[OtherObject]] = 
  javaMap.asScala.map { case (key, value) => 
    key -> Set(value.asScala.toSeq: _*)
  }.toMap
// This will yield a Map[SomeObject, Set[OtherObject]]

Causes

• Using mapAsScalaMap directly, which retains Java collection types instead of converting to Scala collections.
• Not correctly handling the conversion from ICollection to Scala Set.

Solutions

• Use a combination of `asScala` and `Set` to achieve the desired conversion.
• Incorporate Scala’s collection conversion utilities such as `scala.jdk.CollectionConverters._` for seamless transformation.

Mistake: Forgetting to import scala.jdk.CollectionConverters._ leading to compilation errors.

Solution: Ensure to include the necessary import statement for collection conversion.

Mistake: Directly assigning the result without transforming collections, ending up with Java types in Scala.

Solution: Always apply the required transformation to ensureScala types are returned.