ComboBox does not populate with observable array list (JavaFX) [duplicate] - javafx

Question

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed last year.
Improve this question
I will be very grateful for your help, I am trying to create JavaFX applications, I want to start creating something on the canvas panel, the code is compiling but no effects, it seems to me that the canvas panel view is not refreshed, maybe some spec will advise what I forgot, I throw in the whole class, below the code the window structure from the scene builder and the project structure.
[![package com.example.rpgfxmaven;
import javafx.animation.AnimationTimer;
import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.AnchorPane;
import javafx.scene.media.MediaPlayer;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.Duration;
import java.io.IOException;
public class GameControler{
final int oryginalnyRozmiarLudzika = 16; // 16x16 tile
final int skala = 3;
final int rozmiarLudzika = skala * oryginalnyRozmiarLudzika;
final int dlugoscPlanszy = 20;
final int szerokoscPlanszy = 15;
final int dlugoscEkranu = rozmiarLudzika*dlugoscPlanszy;
final int szerokoscEkranu = rozmiarLudzika*szerokoscPlanszy;
#FXML
private Canvas canvaspane = new Canvas(dlugoscEkranu, szerokoscEkranu);
GraphicsContext content;
public static MediaPlayer mediaPlayer;
public void start(Stage primaryStage) throws IOException {
FXMLLoader loader = new FXMLLoader(this.getClass().getResource("maingame-window.fxml"));
AnchorPane anchorPane= loader.load();
anchorPane.setPrefSize(dlugoscEkranu+100, szerokoscEkranu+75);
Scene scene = new Scene(anchorPane);
primaryStage.setScene(scene);
primaryStage.show();
content = canvaspane.getGraphicsContext2D();
startGame();
}
public void startGame()
{
Timeline timeline = new Timeline(new KeyFrame(Duration.millis(10), e ->run(content)));
timeline.setCycleCount(Timeline.INDEFINITE);
}
public void run(GraphicsContext content) {
content.setFill(Color.BLUE);
content.fillRect(100, 100, rozmiarLudzika,rozmiarLudzika);
}
}

Answer 1

This is wrong:
#FXML
private Canvas canvaspane = new Canvas(dlugoscEkranu, szerokoscEkranu);
You should never set an #FXML injected field to a new value.
The fxml loader will already have created an instance of the #FXML field and linked that into the object tree returned by the loader.
If you assign the field to a new value, the new value will not be in the loaded object tree added to the scene graph, so it will never be seen. Only the empty canvas created by the loader will be seen.
You almost definitely have other issues with your application outside of this, but I can't really outline them in detail here.