将 VBox 和 StackPane 放入另一个 StackPane 后，按钮不起作用

Question

我试图在屏幕中间放置一个TextField，同时在其周围放置一个Circle，并在圆圈下方放置一个按钮。所以我用圆圈和按钮制作了一个VBox，以及一个只有TextField 的StackPane。我制作了另一个StackPane 将VBox 和StackPane 放在同一个场景中，但现在按钮不起作用。我真的不知道是什么原因造成的。

以下是我目前的代码。

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package circleandtextbox;

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

/**
 *
 * @author diego
 */
public class CircleAndTextBox extends Application {
    
    @Override
    public void start(Stage primaryStage) {
        int programX = 400;
        int programY = 400;
        int circleRadius = 100;
        Circle circle = new Circle(programX / 2,programY / 2,circleRadius);
        circle.setStroke(Color.RED);
        circle.setStrokeWidth(3);
        circle.setFill(Color.TRANSPARENT);
        
        TextField input = new TextField();
        input.setMaxWidth(100);
        
        Button btn = new Button();
        btn.setText("Change the size of the circle");
        btn.setOnAction((ActionEvent event) -> {
            System.out.println("It worked!");
        });
        
        VBox root = new VBox();
        root.setAlignment(Pos.CENTER);
        root.setSpacing(10);
        root.getChildren().addAll(circle,btn);
        

        StackPane textBox = new StackPane();
        textBox.setAlignment(Pos.CENTER);
        textBox.getChildren().add(input);
        
        StackPane together = new StackPane();
        together.getChildren().addAll(root,textBox);
        
        Scene scene = new Scene(together, programX, programY);
        
        primaryStage.setTitle("Circle code");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }
    
}

Answer 1

您的第二个StackPane 覆盖了您的VBox，隐藏了它的Button。要查看效果，请更改

together.getChildren().addAll(root, textBox);

到

together.getChildren().addAll(textBox , root);

当然，现在TextField 已覆盖。相反，对圆圈和字段使用单个 StackPane：

StackPane textBox = new StackPane();
textBox.setAlignment(Pos.CENTER);
textBox.getChildren().addAll(circle, input);

然后使用按钮将结果添加到VBox。

VBox root = new VBox();
root.setAlignment(Pos.CENTER);
root.setSpacing(10);
root.setPadding(new Insets(16));
root.getChildren().addAll(textBox, btn);

还可以考虑使用Spinner 和/或Slider（见here）来控制大小。测试代码：

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TextField;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

/**
 * @author diego
 * @see https://stackoverflow.com/a/64852023/230513
 * @see https://stackoverflow.com/a/37935114/230513
 */
public class CircleAndTextBox extends Application {
    
    @Override
    public void start(Stage primaryStage) {
        int programX = 400;
        int programY = 400;
        int circleRadius = 100;
        Circle circle = new Circle(programX / 2,programY / 2,circleRadius);
        circle.setStroke(Color.RED);
        circle.setStrokeWidth(3);
        circle.setFill(Color.TRANSPARENT);
        
        TextField input = new TextField();
        input.setMaxWidth(100);
        
        Button btn = new Button();
        btn.setText("Change the size of the circle");
        btn.setOnAction((ActionEvent event) -> {
            System.out.println("It worked!");
        });
        
        StackPane textBox = new StackPane();
        textBox.setAlignment(Pos.CENTER);
        textBox.getChildren().addAll(circle, input);
        VBox root = new VBox();
        root.setAlignment(Pos.CENTER);
        root.setSpacing(10);
        root.setPadding(new Insets(16));
        root.getChildren().addAll(textBox, btn);
        
        Scene scene = new Scene(root);
        
        primaryStage.setTitle("Circle code");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }
}