Question

I want to send class data through the Scala RemoteActor API. I made a custom ClassLoader but it has trouble loading the class [B. I have found out that it represents byte[] in Java. How could I handle this problem? Here is the loadClass method of my ClassLoader.

override def loadClass(name: String): Class[_] = {
if(ClientEntry.verbose) println("loadClass "+name)
var c = findLoadedClass(name)

if (c == null) {
  try {
    c = findSystemClass(name)
  } catch { case _ => null}
}
if (c == null) {
  try {
    c = defaultloader.loadClass(name)
  } catch {
    case _ => c = loadRemoteClass(name)
  }
}
  resolveClass(c)
  c
}   

Answer 1

The java class byte[] is synonymous with Array[Byte] so if you encounter a class named "[B" then one could simply get the class directly classOf[Array[Byte]] since is a primitive of the language.

if ( name == "[B" )
  c = classOf[Array[Byte]]

Unfortunately, things are more complicated than that. There are more java array primitives that need to be handled as well. See how the following classes are named.

println( classOf[Array[Boolean]].getName ) // "[Z"
println( classOf[Array[Byte]].getName ) // "[B"
println( classOf[Array[Char]].getName ) // "[C"
println( classOf[Array[Int]].getName ) // "[I"
println( classOf[Array[Long]].getName ) // "[J"
println( classOf[Array[Double]].getName ) // "[D"
println( classOf[Array[Float]].getName ) // "[F"
println( classOf[Array[String]].getName ) // "[Ljava.lang.String;"
println( classOf[Array[Any]].getName ) // "[Ljava.lang.Object;"
println( classOf[Array[Option[Any]]].getName ) // "[Lscala.Option;"

Notice the type erasure on the last one. And also nested arrays need to be handled as well.

println( classOf[Array[Array[Boolean]]].getName ) // "[[Z"
println( classOf[Array[Array[Array[Boolean]]]].getName ) // "[[[Z"
println( classOf[Array[Array[Option[_]]]].getName ) // "[[Lscala.Option;"
println( classOf[Array[Array[Array[Option[_]]]]].getName ) // "[[[Lscala.Option;"