Unable to update button display data - button

Question

I am learning Kotlin and TornadoFX to program a very simple task: two buttons, one with Int 1 and other with Int 200. When I click the button one, I would like to update and display button one with Int 2 and the other with Int 201. The following program will allowed me to check the update data and all seemed to be correct. My question is why the display on the buttons would not be updated according.
Please help.
class MainView : View("Hello TornadoFX") {
val controllera: ControllerA by inject()
val i: Int? = 1
val j: Int? = 2
override val root = hbox {
button(controllera.s1.toString()) {
setOnAction {
setId(i.toString())
println(" in view button 1 s1: { ${controllera.s1.toString()} }")
controllera.temp(i)
}
}
button(controllera.s2.toString()) {
setOnAction {
setId(j.toString())
println(" in view button 2 s2: { ${controllera.s2.toString()} }")
controllera.temp(j)
}
}
label(title) {
addClass(Styles.heading)
}
}
}
class ControllerA :Controller(){
var s1: Int =1
var s2: Int = 200
fun temp(k: Int?) {
when( k) {
1 -> {println("botton ID " +k)
println(" current value of s1: $s1 ")
s1 = s1+1
println(" new value of s1 to update: $s1 ")
s2 = s2 +1
println(" new value of s2 to update: $s2 ")}
2 -> {
println("botton ID " + k)
println("current value of s2: $s2 ")}
else -> println("default")
}
}
}
test output at various location:
in view button 1 s1: { 1 } //In MainView
botton ID 1 //in ControllerA
s1: 1
new value of s1 to update: 2
new value of s2 to update: 201
in view button 2 s2: { 201 } //in MainView
botton ID 2 //in ControllerA
current value of s2: 201
Note: those updated data will not be display on button text.

Answer 1

You need to use observable properties and bindings. Just starting writing code without reading about the framework is not a good approach. I suggest you read the guide as a starting point. Here is your code rewritten so that each button will display and increase the corresponding number on click:
class MainView : View("Hello TornadoFX") {
val controllera: ControllerA by inject()
val myModel: MyModel by inject()
override val root = hbox {
button(myModel.s1.asString()) {
action {
controllera.inc(myModel.s1)
}
}
button(myModel.s2.asString()) {
action {
controllera.inc(myModel.s2)
}
}
label(title)
}
}
class MyModel : ViewModel() {
val s1 = SimpleIntegerProperty(1)
val s2 = SimpleIntegerProperty(200)
}
class ControllerA : Controller() {
fun inc(v: IntegerProperty) {
v.value = v.value + 1
}
}