JavaFX程序单选钮中挑选颜色

Question

编写一个JavaFX程序，允许用户从5个单选钮中挑选一种颜色，在一个正方形中显示相应的颜色。

想请教为什么我运行出来是白板，什么都没有

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.scene.control.RadioButton;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.layout.StackPane;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class ColorOptions extends Application
{
    public void start(Stage primaryStage)
    {
        ColorOptionsPane pane = new ColorOptionsPane();
        pane.setAlignment(Pos.CENTER);
        pane.setStyle("-fx-background-color:white");
        
        Scene scene = new Scene(pane,500,150);
        
        primaryStage.setTitle("Color Options");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}

import javafx.event.ActionEvent;
import javafx.geometry.Pos;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.layout.StackPane;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class ColorOptionsPane extends HBox
{
    //private rectangle color;
    private RadioButton redButton,greenButton,orangeButton,yellowButton,blueBUtton;
    private Rectangle colorBox;
    
    public void ColorOptionPane()
    {
        
        colorBox = new Rectangle(100, 100, Color.RED);
        StackPane colorPane=new StackPane(colorBox);
        colorPane.setPrefSize(300,100);
        
        //放到一个组里
        ToggleGroup group = new ToggleGroup();
        
        //设置红色单选钮
        RadioButton redButton = new RadioButton("Red");
        redButton.setToggleGroup(group);
        redButton.setSelected(true);
        redButton.setOnAction(this::processRadioButtonAction);
        //设置绿色单选钮
        RadioButton greenButton = new RadioButton("Green");
        greenButton.setToggleGroup(group);
        greenButton.setSelected(true);
        greenButton.setOnAction(this::processRadioButtonAction);
        //设置橘色单选钮
        RadioButton orangeButton = new RadioButton("Orange");
        orangeButton.setToggleGroup(group);
        orangeButton.setSelected(true);
        orangeButton.setOnAction(this::processRadioButtonAction);
        //设置黄色单选钮
        RadioButton yellowButton = new RadioButton("Yellow");
        yellowButton.setToggleGroup(group);
        yellowButton.setSelected(true);
        yellowButton.setOnAction(this::processRadioButtonAction);
        //设置蓝色单选钮
        RadioButton blueButton = new RadioButton("Blue");
        blueButton.setToggleGroup(group);
        blueButton.setSelected(true);
        blueButton.setOnAction(this::processRadioButtonAction);
        
        VBox options = new VBox(redButton,greenButton,orangeButton,yellowButton,blueBUtton);
        options.setAlignment(Pos.CENTER_LEFT);
        options.setSpacing(10);
        
        setSpacing(20);
        getChildren().addAll(options,colorBox);
    }
    
    public void processRadioButtonAction(ActionEvent event)
    {
        if(redButton.isSelected())
            colorBox.setFill(Color.RED);
        else if (greenButton.isSelected())    
            colorBox.setFill(Color.GREEN);
        else if (orangeButton.isSelected())
            colorBox.setFill(Color.ORANGE);
        else if (yellowButton.isSelected())
            colorBox.setFill(Color.YELLOW);    
        else
            colorBox.setFill(Color.BLUE);    
    }
}

```.

Answer 1

你这语法错的有点多，涉及到构造函数，局部变量 还有继承多看看，这个类代码替换一下就可以了

import javafx.event.ActionEvent;
import javafx.geometry.Pos;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.layout.StackPane;
import javafx.scene.text.Text;
import javafx.scene.text.Font;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class ColorOptionsPane extends HBox {
    //private rectangle color;
    private RadioButton redButton, greenButton, orangeButton, yellowButton, blueButton;
    private Rectangle colorBox;

    public ColorOptionsPane() {
        super();
        colorBox = new Rectangle(100, 100, Color.RED);
        StackPane colorPane = new StackPane(colorBox);
        colorPane.setPrefSize(300, 100);

        //放到一个组里
        ToggleGroup group = new ToggleGroup();

        //设置红色单选钮
        redButton = new RadioButton("Red");
        redButton.setToggleGroup(group);
        redButton.setSelected(true);
        redButton.setOnAction(this::processRadioButtonAction);
        //设置绿色单选钮
        greenButton = new RadioButton("Green");
        greenButton.setToggleGroup(group);
        greenButton.setSelected(true);
        greenButton.setOnAction(this::processRadioButtonAction);
        //设置橘色单选钮
        orangeButton = new RadioButton("Orange");
        orangeButton.setToggleGroup(group);
        orangeButton.setSelected(true);
        orangeButton.setOnAction(this::processRadioButtonAction);
        //设置黄色单选钮
        yellowButton = new RadioButton("Yellow");
        yellowButton.setToggleGroup(group);
        yellowButton.setSelected(true);
        yellowButton.setOnAction(this::processRadioButtonAction);
        //设置蓝色单选钮
        blueButton = new RadioButton("Blue");
        blueButton.setToggleGroup(group);
        blueButton.setSelected(true);
        blueButton.setOnAction(this::processRadioButtonAction);

        VBox options = new VBox(redButton, greenButton, orangeButton, yellowButton, blueButton);
        options.setAlignment(Pos.CENTER_LEFT);
        options.setSpacing(10);

        setSpacing(20);
        getChildren().addAll(options, colorBox);
    }

    public void processRadioButtonAction(ActionEvent event) {
        if (redButton.isSelected())
            colorBox.setFill(Color.RED);
        else if (greenButton.isSelected())
            colorBox.setFill(Color.GREEN);
        else if (orangeButton.isSelected())
            colorBox.setFill(Color.ORANGE);
        else if (yellowButton.isSelected())
            colorBox.setFill(Color.YELLOW);
        else
            colorBox.setFill(Color.BLUE);
    }
}