Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
855 views
in Technique[技术] by (71.8m points)

scala - How can I access a method which return Option object?

I have to call method which returns Option[List[Obj]].

After I call I need to iterate the List and print the Obj attributes.

object Tester{
  def main(args:Array[String]) {
    val ymlFilename ="some.yml";
  val entities: Option[QueryEntities] =  InputYamlProcessor.process(ymlFilename)

        for( e: QueryEntities  <- entities ){
          /// this is not working
           //How to access the columnFamily, fromData and toDate ?
        }
  }

Complete sample

https://gist.github.com/shatestest/fdeaba767d78e171bb6c08b359fbd1bf

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

The most iconic way ot do it is to unwrap values with scala is to use pattern matching to unwrap the value.

entities match {
    case Some(queryEntities: QueryEntities) => 
      queryEntities.entities.foreach { case e =>
        println(e.columnFamily)
        println(e.fromDate.getOrElse("defaultFromDateHere")
        println(e.toDate.getOrElse("defaultToDateHere"))
      }
    case None => println("No value")
}

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...