连接具有StringConverter的Slider和Spinner

本文介绍了连接具有StringConverter的Slider和Spinner的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

对于数字输入，将模拟控件同步到文本显示有时会很方便.在此Swing 示例中，一个JSpinner和JSlider分别监听更改事件，并分别更新对方的模型匹配.如下所示，一个类似的JavaFX程序将 Spinner 和 Slider ，并且这些侦听器可以使控件保持协调一致:

For numeric input, it's sometimes convenient to synchronize an analog control to a text display. In this Swing example, a JSpinner and a JSlider each listen for change events, and each updates the other's model to match. A similar JavaFX program, shown below, connects a Spinner and a Slider, and these listeners keep the controls coordinated:

slider.valueProperty().addListener((Observable o) -> { spinner.getValueFactory().setValue(slider.getValue()); }); spinner.valueProperty().addListener((Observable o) -> { slider.setValue((double) spinner.getValue()); });

不幸的是，当我在微调器的SpinnerValueFactory中添加StringConverter时，初始值是未格式化的，直到更改了任何一个控件为止-即使在再次明确设置初始值的情况下，在之后添加了转换器:

Unfortunately, when I added a StringConverter to the spinner's SpinnerValueFactory, the initial value was unformatted until either control was changed—even when setting the initial value explicitly again, after adding the converter:

spinner.getValueFactory().setConverter(…); spinner.getValueFactory().setValue(INITIAL_VALUE);

我要去哪里错了?

import java.text.NumberFormat; import javafx.application.Application; import javafx.beans.Observable; import javafx.geometry.Insets; import javafx.scene.Scene; import javafx.scene.control.Slider; import javafx.scene.control.Spinner; import javafx.scene.layout.GridPane; import javafx.stage.Stage; import javafx.util.converter.PercentageStringConverter; /** * @see stackoverflow/a/6067986/230513 */ public class SpinSlider extends Application { private static final double MIN = 0; private static final double MAX = 1; private static final double INITIAL_VALUE = 0.5; private static final double STEP_INCREMENT = 0.1; @Override public void start(Stage primaryStage) { primaryStage.setTitle("SpinSlider"); Slider slider = new Slider(MIN, MAX, INITIAL_VALUE); slider.setBlockIncrement(STEP_INCREMENT); Spinner spinner = new Spinner(MIN, MAX, INITIAL_VALUE, STEP_INCREMENT); spinner.getValueFactory().setConverter( new PercentageStringConverter(NumberFormat.getPercentInstance())); spinner.getValueFactory().setValue(INITIAL_VALUE); slider.valueProperty().addListener((Observable o) -> { spinner.getValueFactory().setValue(slider.getValue()); }); spinner.valueProperty().addListener((Observable o) -> { slider.setValue((double) spinner.getValue()); }); GridPane root = new GridPane(); root.addRow(0, slider, spinner); root.setPadding(new Insets(8, 8, 8, 8)); root.setHgap(8); Scene scene = new Scene(root); primaryStage.setScene(scene); primaryStage.show(); } public static void main(String[] args) { launch(args); } }

推荐答案

您的INITIAL_VALUE首先用作微调器的构造函数的initialValue参数.在内部，微调器的具体 SpinnerValueFactory 是在其value属性中添加ChangeListener的DoubleSpinnerValueFactory；当再次设置初始值时，该值实际上并没有更改.有两种方法可以说明自己:

Your INITIAL_VALUE is first used as the initialValue parameter to the spinner's constructor. Internally, the spinner's concrete SpinnerValueFactory is a DoubleSpinnerValueFactory that adds a ChangeListener to its value property; when the initial value is set again, the value hasn't really changed. Two approaches suggest themselves:

为构造函数指定一个不同的值，并在添加转换器后设置所需的值:

Specify a different value to the constructor and set the desired one after adding the converter: Spinner spinner = new Spinner(MIN, MAX, -42, STEP_INCREMENT); spinner.getValueFactory().setConverter(…); spinner.getValueFactory().setValue(INITIAL_VALUE);

构造具有所需初始值的SpinnerValueFactory并将其用于构造微调器:

Construct a SpinnerValueFactory with the desired initial value and use it to construct the spinner:

SpinnerValueFactory factory = new SpinnerValueFactory .DoubleSpinnerValueFactory(MIN, MAX, INITIAL_VALUE, STEP_INCREMENT); factory.setConverter(…); Spinner spinner = new Spinner(factory);

此外，下面的示例将两个侦听器替换为双向绑定，该双向绑定使用弱侦听器允许垃圾回收属性:

In addition, the example below replaces the two listeners with a bidirectional binding, which uses weak listeners to allow garbage collection of properties:

slider.valueProperty().bindBidirectional( spinner.getValueFactory().valueProperty());

微调器和滑块可以相互控制.更常见的是，每个人在控制其他模型拥有的财产的过程中都可以保持同步:

Trivially, the spinner and slider can control each other. More commonly, each can stay synchronized in the course of controlling a property held by another model:

model.xProperty().bindBidirectional(slider.valueProperty()); model.xProperty().bindBidirectional(spinner.getValueFactory().valueProperty());

import java.text.NumberFormat; import javafx.application.Application; import javafx.geometry.Insets; import javafx.scene.Scene; import javafx.scene.control.Slider; import javafx.scene.control.Spinner; import javafx.scene.control.SpinnerValueFactory; import javafx.scene.layout.GridPane; import javafx.stage.Stage; import javafx.util.converter.PercentageStringConverter; /** * @see stackoverflow/a/55427307/230513 * @see stackoverflow/a/6067986/230513 */ public class SpinSlider extends Application { private static final double MIN = 0; private static final double MAX = 1; private static final double INITIAL_VALUE = 0.5; private static final double STEP_INCREMENT = 0.1; @Override public void start(Stage primaryStage) { primaryStage.setTitle("SpinSlider"); Slider slider = new Slider(MIN, MAX, INITIAL_VALUE); slider.setBlockIncrement(STEP_INCREMENT); SpinnerValueFactory factory = new SpinnerValueFactory .DoubleSpinnerValueFactory(MIN, MAX, INITIAL_VALUE, STEP_INCREMENT); factory.setConverter(new PercentageStringConverter( NumberFormat.getPercentInstance())); Spinner spinner = new Spinner(factory); slider.valueProperty().bindBidirectional(spinner.getValueFactory().valueProperty()); GridPane root = new GridPane(); root.addRow(0, slider, spinner); root.setPadding(new Insets(8, 8, 8, 8)); root.setHgap(8); Scene scene = new Scene(root); primaryStage.setScene(scene); primaryStage.show(); } public static void main(String[] args) { launch(args); } }