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POHow to convert from from java.util.Map to a Scala Map
 

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    <p>A Java API returns a <code>java.util.Map&lt;java.lang.String,java.lang.Boolean&gt;</code>;. I would like to put that into a <code>Map[String,Boolean]</code></p> <p>So imagine we have:</p> <pre><code>var scalaMap : Map[String,Boolean] = Map.empty val javaMap = new JavaClass().map() // Returns java.util.Map&lt;java.lang.String,java.lang.Boolean&gt; </code></pre> <p>You can't do <code>Map.empty ++ javaMap</code>, because the ++ method does not know about Java maps. I tried:</p> <pre><code>scalaMap = Map.empty ++ new collection.jcl.MapWrapper[String,Boolean] { override def underlying = javaMap } </code></pre> <p>and:</p> <pre><code>scalaMap = Map.empty ++ new collection.jcl.MapWrapper[java.lang.String,java.lang.Boolean] { override def underlying = javaMap } </code></pre> <p>These both fail to compile, because of the generics - <code>java.lang.String</code> is not the same as a scala String.</p> <p>Is there a good way of doing this, short of copying the map manually?</p> <p>EDIT: Thanks, all good answers, I learned a lot from all of them. However, I made a mistake by posting a simpler problem here than the one I actually have. So, if you allow me, I'll generalise the question - What the API actually returns is</p> <pre><code>java.util.Map&lt;java.lang.String, java.util.Map&lt;SomeJavaEnum,java.lang.String&gt;&gt; </code></pre> <p>And I need to move this to Map[String, Map[SomeJavaEnum,String]]</p> <p>It probably does not seem like too much of a complication, but it adds an extra level of type erasure, and the only way I found of moving this to a Scala map was deep-copying it (using some of the techniques you suggested below). Anyone any hints? I kind of solved my problem by defining an implicit conversion for my exact types, so at least the ugliness is hidden in its own trait, but still feels a bit clumsy deep copying the lot.</p>
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    1. COI quite like the Conversions answer I got from the scala-user group. Just need to check if it works... But it's way too late here now, so will post back soon...
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