Scala function programming

1. Arbitrary multi parameters funcs

sum(1,2,3,4,5) = sum(1 to 5: _*)
the equal '=' can be ignored if there is none  return val

1 def sum(args: Int*) = {
2     var result = 0
3     for(arg <- args) result += arg
4     result    
5 }

 

　　 scala Array Buffer to Java List:

1 import scala.collection.JavaConversions.bufferAsJavaList
2 import scala.collection.mutable.ArrayBuffer
3 val command = ArrayBuffer("ls","-al","/home/mike")
4 val pb = new ProcessBuilder(command)

　　reverse operation

1 import scala.collection.JavaConversion.asScalaBuffer
2 import scala.collection.mutable.Buffer
3 val cmd:Buffer[String] = pb.command()

　　Hash Map

1 val hs01 = Map("s01" -> 342342,"s02" -> 4245)
2 hs01.getOrElse("s01",0)