Converting Map[String, Double] to java.util.Map[String, java.lang.Double]

Question

I thought we can rely on implicit conversion which converts scala.Double to java.lang.Double. So I tried the following:

import scal         


        

Answer 1

You need the boxed version of double:

import scala.collection.JavaConverters._

m.mapValues(Double.box).asJava

The implicits are able to convert a value of Double to java.lang.Double, but not a Map[String,Double] to java.util.Map[String,java.lang.Double].

String requires no conversion because String is a java.lang.String while Double is a double (primitive).