GUI enabling/disabling of controls: Difference between revisions

=={{header|Kotlin}}==

{{libheader|JavaFX}}

{{trans|Java}}

<lang scala>// version 1.2.21

import javafx.application.Application

import javafx.beans.property.SimpleLongProperty

import javafx.scene.Scene

import javafx.scene.control.Button

import javafx.scene.control.TextField

import javafx.scene.layout.HBox

import javafx.scene.layout.VBox

import javafx.stage.Stage

import javafx.util.converter.NumberStringConverter

import javafx.event.ActionEvent

val digits = Regex("[0-9]*")

class InteractFX : Application() {

override fun start(stage: Stage) {

val input = object : TextField("0") {

// only accept numbers as input

override fun replaceText(start: Int, end: Int, text: String) {

if (text.matches(digits)) super.replaceText(start, end, text)

}

// only accept numbers on copy + paste

override fun replaceSelection(text: String) {

if (text.matches(digits)) super.replaceSelection(text)

}

}

// when the textfield is empty, replace text with "0"

input.textProperty().addListener { _, _, newValue ->

if (newValue == null || newValue.trim().isEmpty()) input.text = "0"

}

// get a bi-directional bound long-property of the input value

val inputValue = SimpleLongProperty()

input.textProperty().bindBidirectional(inputValue, NumberStringConverter())

// textfield is disabled when the current value is other than "0"

input.disableProperty().bind(inputValue.isNotEqualTo(0))

val increment = Button("Increment")

increment.addEventHandler(ActionEvent.ACTION) { inputValue.set(inputValue.get() + 1) }

// increment button is disabled when input is >= 10

increment.disableProperty().bind(inputValue.greaterThanOrEqualTo(10))

val decrement = Button("Decrement")

decrement.addEventHandler(ActionEvent.ACTION) { inputValue.set(inputValue.get() - 1) }

// decrement button is disabled when input is <= 0

decrement.disableProperty().bind(inputValue.lessThanOrEqualTo(0))

// layout

val root = VBox()

root.children.add(input)

val buttons = HBox()

buttons.children.addAll(increment, decrement)

root.children.add(buttons)

stage.scene = Scene(root)

stage.sizeToScene()

stage.show()

}

}

fun main(args: Array<String>) {

Application.launch(InteractFX::class.java, *args)

}</lang>