CellCache renders unexpectedly in TableView with tornadoFX - javafx

Question

I just puzzled by the cellCache funtion usage in TornadoFX with Kotlin. The render is always strange and unexpected, what happens with that? The code is here:
data class Person(var name : String, var age : Int, var sex : Boolean)
class MyView: View()
{
val list = listOf<Person>(
Person("Name A", 20, false),
Person("Name B", 22, false),
Person("Name C", 21, true),
Person("Name D", 30, true),
Person("Name E", 35, true)
).observable()
override val root = stackpane {
vbox {
tableview(items = list) {
column("Name", Person::name)
column("Age", Person::age)
column("Sex", Person::sex).cellCache{
checkbox{
isSelected = it
setOnAction {
println("Selection: $isSelected")
}
}
}
}
}
}
}
I expect all the rows will render with a checkbox in column "Sex", but the code above will just display two: one selected and another unselected, what the hell is going on with cellcache?
I also find changing the data class with the one below, and it is all right:
data class Person(var name : String, var age : Int, var sex : SimpleBooleanProperty)
However I must change a lot with the data class properties in this way, I also don't know why.
Help me, and thanks in advance!

Answer 1

The cellCache creates a unique cell per item in your list. If your items does not implement meaningful equals and hashCode functions you will run into trouble with cellCache since the same cell will be used for multiple underlying items.
Adding equals and hashCode implementation that ensures each item is unique should solve the problem. It seems that the default implementation in a Kotlin data class doesn't cut it :)
If you can't or won't provide equals and hashCode implementations I would suggest using cellFormat instead, which doesn't rely on object equality to produce a unique cell.
I'm sorry this isn't made clear in the guide, I will update the TableView part with more information and a warning about the use of cellCache.