How to create an Option dialog in Scala

Question

I've been trying to create an Option dialog that isn't limited to two or three choices (Option.YesNo or Option.YesNoCancel), but I've been unable to find a way to use anything but these built-in options. Specifically, the following refuses to accept anything that I can put for optionType:

    object Choices extends Enumeration {
      type Choice = Value
      val red, yellow, green, blue = Value
    }
        val options = List("Red", "Yellow", "Green", "Blue")
        label.text = showOptions(null,
                    "What is your favorite color?",
                    "Color preference",
                    optionType = Choices.Value,
                    entries = options, 
                    initial = 2) match {
          case Choice.red => "Red"
          case Choice.yellow => "Yellow"
          case Choice.green => "Green"
          case Choice.blue => "Blue"
          case _ => "Some other color"
        }

score 1 · Answer 1 · answered Dec 07 '13 at 00:21

Yes, it's one of the many design bugs in Scala-Swing. You can write your own showOptions method:

import swing._
import Swing._
import javax.swing.{UIManager, JOptionPane, Icon}

def showOptions[A <: Enumeration](
                parent: Component = null, 
                message: Any, 
                title: String = UIManager.getString("OptionPane.titleText"),  
                messageType: Dialog.Message.Value = Dialog.Message.Question, 
                icon: Icon = EmptyIcon, 
                entries: A,
                initial: A#Value): Option[A#Value] = {
  val r = JOptionPane.showOptionDialog(
                  if (parent == null) null else parent.peer,  message, title, 0, 
                  messageType.id, Swing.wrapIcon(icon),  
                  entries.values.toArray[AnyRef], initial)
  if (r < 0) None else Some(entries(r))
}

val res = showOptions(message = "Color", entries = Choices, initial = Choices.green)

If you want to pass in strings instead, change to entries: Seq[Any], initial: Int, use entries(initial) in the call, and just return r of Int.

That works. I ended up using JOptionPane directly, since I'm more familiar with it. Still, I can't help but wonder if it's really a bug or if I just haven't found the right incantation to make showOptions accept my argument types. — David Matuszek, Dec 07 '13 at 02:56
It is a bug, because it interprets the result in terms of the `OptionPane.Result` enumeration which will fail for any indices exceeding this enumeration. — 0__, Dec 07 '13 at 03:13

score 0 · Answer 2 · answered Dec 06 '13 at 19:19

0

optionType isn't for passing in a Scala type, and actually I'm not sure what its purpose is in this API. But you can just set optionType = Options.YesNoCancel, and that should work, I think.

answered Dec 06 '13 at 19:19

Robin Green

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Options.YesNoCancel works for three of the choices, but crashes on the fourth. – David Matuszek Dec 06 '13 at 19:57
Can you be more specific? What happens? – Robin Green Dec 06 '13 at 19:58
After using up the three available responses (Result.Yes, Result.No, Result.Cancel), the only remaining thing I can match is _. So after those I use "case _ =>". I can map the three valid responses onto "red", "yellow", "green", but if I click blue, I get "java.util.NoSuchElementException: key not found: 3" instead of my final case. – David Matuszek Dec 06 '13 at 20:49
Ah yes. This does seem like a bug in scala-swing. The `showOptions` method really doesn't seem to have been properly designed. – Robin Green Dec 06 '13 at 20:52

How to create an Option dialog in Scala

2 Answers2