Pane will not add all children unless I individually add text first in JAVA / Java FX

DntMesArnd :

I'm working on a homework problem where I am making a cylinder using Java and Java FX. The cylinder is to re-size based on the size of the window.

I start by creating an ellipse at the top, two vertical lines, and two arc's at the bottom (one dashed). I have bound them to the pane, so they change as the window gets re-sized.

When I try to run it, the program compiles fine (in Intelli-J), the new Java window show up, but the program seems to hang there. I can't access the window, just see it in the program bar on my Mac.

For some reason, when I add text individually to the pane before I add all with my shapes, it works fine?

Code is below. Any help would be greatly appreciated!

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.Ellipse;
import javafx.scene.shape.Line;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class CylinderResize extends Application {
    @Override
    public void start(Stage primaryStage) {
        //Create Pane
        Pane pane = new Pane();
        Scene scene = new Scene(pane);

        //Create Elipse for top
        Ellipse ellipse = new Ellipse();
        //Make the Center X property half of the pane width
        ellipse.centerXProperty().bind(pane.widthProperty().divide(2));
        //Height starts 1/3 the way down
        ellipse.centerYProperty().bind(pane.heightProperty().divide(3));
        //X Radius  is 1/4 the width property and y radius is 1/8 WIDTH property
        ellipse.radiusXProperty().bind(pane.widthProperty().divide(4));
        ellipse.radiusYProperty().bind(pane.heightProperty().divide(8));
        ellipse.setStroke(Color.BLACK);
        ellipse.setFill(Color.WHITE);

        //Create Solid arch for  bottom
        Arc solidArc = new Arc();
        solidArc.centerXProperty().bind(pane.widthProperty().divide(2));
        solidArc.centerYProperty().bind(pane.heightProperty().multiply(2).divide(3));
        solidArc.radiusXProperty().bind(pane.widthProperty().divide(4));
        solidArc.radiusYProperty().bind(pane.heightProperty().divide(8));
        solidArc.setStartAngle(180);
        solidArc.setLength(180);
        solidArc.setType(ArcType.OPEN);
        solidArc.setStroke(Color.BLACK);
        solidArc.setFill(Color.WHITE);

        //Create dashed line for bottom
        Arc dashedArc = new Arc();
        dashedArc.centerXProperty().bind(pane.widthProperty().divide(2));
        dashedArc.centerYProperty().bind(pane.heightProperty().multiply(2).divide(3));
        dashedArc.radiusXProperty().bind(pane.widthProperty().divide(4));
        dashedArc.radiusYProperty().bind(pane.heightProperty().divide(8));
        dashedArc.setStartAngle(0);
        dashedArc.setLength(180);
        dashedArc.setType(ArcType.OPEN);
        dashedArc.setFill(Color.WHITE);
        dashedArc.setStroke(Color.BLACK);

        dashedArc.getStrokeDashArray().addAll(6.0, 21.0);


        //Create Vertical Lines for the sides
        Line leftLine = new Line();
        leftLine.startXProperty().bind(ellipse.centerXProperty().subtract(ellipse.radiusXProperty()));
        leftLine.startYProperty().bind(ellipse.centerYProperty());
        leftLine.endXProperty().bind(solidArc.centerXProperty().subtract(solidArc.radiusXProperty()));
        leftLine.endYProperty().bind(solidArc.centerYProperty());
        leftLine.setStroke(Color.BLACK);

        Line rightLine = new Line();
        rightLine.startXProperty().bind(ellipse.centerXProperty().add(ellipse.radiusXProperty()));
        rightLine.startYProperty().bind(ellipse.centerYProperty());
        rightLine.endXProperty().bind(solidArc.centerXProperty().add(solidArc.radiusXProperty()));
        rightLine.endYProperty().bind(solidArc.centerYProperty());
        rightLine.setStroke(Color.BLACK);

        //Test with a text box
        Text text = new Text(25, 25, "WHY IS THIS REQUIRED?????");

        //Add the objects to the pane
        pane.getChildren().add(text); //WHEN I TAKE THIS LINE OUT, THE PROGRAM JUST HANGS.........
        pane.getChildren().addAll(ellipse, solidArc, dashedArc, leftLine, rightLine);

        //Set Up Stage
        primaryStage.setTitle("Ellipse that scales");
        primaryStage.setScene(scene);
        primaryStage.show();

    }
}

Matt :

Its not that your program is hanging but it is the stage is not sizing to anything you can fix that by setting a height and width like so

primaryStage.setWidth(200);
primaryStage.setHeight(200);

The reason the text was fixing it was because it was making a base size that you can visibly see when you remove it you can no longer see it because its so small

Also well done on the project I think its cool