How to create a new ButtonGroup in scala containing RadioButtons?

Question

I am having trouble creating a ButtonGroup containing radio buttons in the Scala Programming Language. The code I am using is as following:

val buttongroup = new ButtonGroup {
  buttons += new RadioButton("One")
  buttons += new RadioButton("Two")
}

and my code for displaying the button group is within a BorderPanel:

layout += new BoxPanel(Orientation.Vertical) {
  buttongroup
} -> BorderPanel.Position.West

However, nothing displays... I've consulted the API and I'm not sure what is wrong!!

Answer 1

You should add a list containing the buttons to the panel, not the buttongroup itself, e.g.:

val radios = List(new RadioButton("One"), new RadioButton("two"))
layout += new BoxPanel(Orientation.Vertical) {
  contents ++= radios         
}

See also this example in the scala swing package itself.

Answer 2

While the button group makes the buttons mututaly exclusive, you still need to add individual buttons to the panel. You can use ButtonGroup.buttons to obtain the list of the buttons:

layout += new BoxPanel(Orientation.Vertical) {
  val buttongroup = new ButtonGroup {
    buttons += new RadioButton("One")
    buttons += new RadioButton("Two")
  }
  contents ++= buttongroup.buttons
} -> BorderPanel.Position.West

If you want the first button to be selected when the toolbar is created, you can add:

buttongroup.select(buttongroup.buttons.head)