Using this code as an example I have written the following to track changes of a slider and put the result into the "speed: Int" variable:
speedSlider.valueProperty.addListener(new ChangeListener[Number] {
@Override
def changed(o: ObservableValue[_ <: Number], oldVal: Number, newVal: Number) {
speed = newVal.intValue()
}
})
But it causes an error:
wrong number of type arguments for scalafx.beans.value.ObservableValue, should be 2
def changed(o: ObservableValue[_ <: Number], oldVal: Number, newVal: Number) {
If I change ObservableValue[_ <: Number]
to ObservableValue[_ <: Number, _ <: Number]
this error disappears but another emerges:
object creation impossible, since method changed in trait ChangeListener of type (x$1: javafx.beans.value.ObservableValue[_ <: Number], x$2: Number, x$3: Number)Unit is not defined
speedSlider.valueProperty.addListener(new ChangeListener[Number] {
^
Any ideas?
Update: I have resolved the errors by replacing ObservableValue
(which was being resolved into the ScalaFX version which I don't really understand) with javafx.beans.value.ObservableValue
. It compiles and throws no errors now, but still doesn't work - the code is never invoked.
Looking at the docs I see you don't need to pass a ChangeListener
but simply an anonymous function with the same signature as the onChange
method
speedSlider.valueProperty.addListener{ (o: javafx.beans.value.ObservableValue[_ <: Number], oldVal: Number, newVal: Number) =>
speed = newVal.intValue
}
Otherwise the method will expect a javafx.beans.value.ChangeListener
I hope this solves the issue.
Just in case someone else encounters this problem. With Scala 3 the following works:
rotate.statusProperty().addListener(new ChangeListener[Animation.Status]() {
override def changed(observableValue: ObservableValue[ _ <: Animation.Status],
oldValue: Animation.Status, newValue: Animation.Status) = {
text2.setText("Was - " + oldValue + ", Now - " + newValue)
}
})
Notice that the anonymous class must have the type parameter fully defined, but not the overridden method.
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