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copied!<p>Fixing the first sample you provided, see the comments:</p> <pre><code>classnames = List[String]("fqcn", "fqcn", "fqcn"....) // close ( with ) not ] for (name <- classnames) { val clazz = classLoader.forName(name) // forName is what loads a class //val actRef = actorSystem.actorOf(Props[clazz]) // still wrong I will explain later } </code></pre> <p>The second sample has a few more issues.</p> <p>First <code>HashMap([String, String, ActorRef]("commonname" -> "Fqcn", someThing))</code>, it's close to be right but with a few key syntactic mistakes. </p> <p>In Scala the <code>[]</code> is used to declare or define type parameters, it seems our case in hand is a matter of definition, in other words, we want to state what type paramaters. There are only a few places Scala allows placing type parameters, it's right classes after class instanciation (e.g <code>new HashMap[String, Int]</code>) and in method call (e.g <code>list.map[String](...)</code>.</p> <p>So, placing the type parameter as in <code>HashMap[String, String, ActorRef](...)</code> would be valid Scala syntax and since HashMap is companion object it would end up after desugaring something like <code>HashMap.apply[String, String, ActorRef](...)</code>.</p> <p>But this expression still have a big problem, HashMap only take two type parameters, one for the keys and one for the values. Looking at your code it seems that the desired key is a tuple. So to make it work: <code>HashMap[(String, String), ActorRef](...)</code></p> <p>Now for the last fix <code>Props[new classobject]</code>, again confusion regarding type parameters. Type parameters takes <strong>types</strong> not instances, any 'new something' would be creating a instance of something. You have to do <code>Props[SomeClass]</code>. As a quick side not the term "class object" usually refers to instance of a class, not the class itself. </p> <p>A syntactic valid version of the second sample:</p> <pre><code>val activeClasses = HashMap[(String, String), ActorRef]( ("commonname" -> "Fqcn", actorOf(Props[SomeClass])) ) </code></pre> <p>Coming back to the first sample and this particular line:</p> <pre><code>val actRef = actorSystem.actorOf(Props[clazz]) </code></pre> <p><code>clazz</code> here is a instance of Class[_], again the above wouldn't even be valid code. It seems that <code>Props.apply[T <: ActorRef]...</code> requires a type and it will take care of instantiating it for you. But you only have Class[_]'s containing the classes. How to solve this? It happens there is another Props.apply that instead takes constructs for the actor classes that will take of the instantiation, look it's signature:</p> <pre><code>def apply(creator: ⇒ Actor) </code></pre> <p>Why not use this one?</p> <pre><code>classnames = List[String]("fqcn", "fqcn", "fqcn"....) for (name <- classnames) { val clazz = classLoader.forName(name) val actRef = actorSystem.actorOf(Props( clazz.newInstance.asInstanceOf[Actor] )) } </code></pre> <p>Assuming the second sample will somehow rely classes from the first:</p> <pre><code>val activeClasses = HashMap[(String, String), ActorRef]( ("commonname" -> "Fqcn", actorOf(Props( clazz.newInstance.asInstanceOf[Actor] ) ) ) </code></pre> <p>A few comments about these samples:</p> <ul> <li>Both type parameters are unnecessary. The compiler can infer then for you.</li> <li>Instead of using <code>(a -> b, c)</code> for defining a tuple whose first element is a tuple, you can use <code>a -> b -></code>, which will result into <code>((a,b),c)</code>. The <code>-></code> is left associative.</li> </ul>

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