我的代码看起来没有问题，我一直收到这个错误

Question

所以我试图使用JavaFX。我尝试使用BPF和JavaFX进行动画处理。在这个节目中，我试图让地球围绕太阳运动。它在运行之前没有给出任何错误，但是当我运行它时会遇到这个错误。可能会发生这种情况，因为我可能没有正确导入图像，但我对此非常有信心。

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.image.Image;
import javafx.stage.Stage;

public class Animation extends Application {
    public int canvasSize = 512;                // constants for relevant sizes
    public double orbitSize = canvasSize / 3;
    public double sunSize = 80;
    public double earthSize = 30;
    public GraphicsContext gc; 
    public Image earth = new Image(getClass().getResourceAsStream("earth.png"));
    public Image sun = new Image(getClass().getResourceAsStream("sun.png"));
            // note loading of images, which should be in package

    /**
     * drawIt ... draws object defined by given image at position and size
     * @param i
     * @param x
     * @param y
     * @param sz
     */
    public void drawIt (Image i, double x, double y, double sz) {
        gc.drawImage(i, x - sz/2, y - sz/2, sz, sz );
    }
    /**
     *  draw system, with Earth at x,y
     * @param x
     * @param y
     */
    private void drawSystem(double x, double y) {
        // now clear canvas and draw sun and moon
        gc.clearRect(0,  0,  canvasSize,  canvasSize);      // clear canvas
        drawIt( sun, canvasSize/2, canvasSize/2, sunSize ); // draw Sun
        drawIt( earth, x, y, earthSize );                   // draw Earth
    }

    /**
     * draw system with Earth at specified angle
     * @param t
     */
    private void drawSystem(double t) {
        double x = canvasSize/2 + orbitSize * Math.cos(t);  // calc x coord
        double y = canvasSize/2 + orbitSize * Math.sin(t);  // and y
        drawSystem(x,y);                                    // and draw system
    }

    /**
     * main function ... sets up canvas and timer
     */
    @Override
    public void start(Stage stagePrimary) throws Exception {
        stagePrimary.setTitle("Solar System");  // set title

        Group root = new Group();               // create group of what is to be shown
        Canvas canvas = new Canvas( canvasSize, canvasSize );
                                                // create canvas to draw on
        root.getChildren().add( canvas );       // add canvas to root
        gc = canvas.getGraphicsContext2D();
                                                // remember context of canvas drawn on
        Scene scene = new Scene( root );        // put root  in a scene
        stagePrimary.setScene( scene );         // apply the scene to the stage

        final long startNanoTime = System.nanoTime();
                                                // for animation, note start time

        new AnimationTimer()                    // create timer
            {
                public void handle(long currentNanoTime) {
                        // define handle for what do at this time
                    double t = (currentNanoTime - startNanoTime) / 1000000000.0; 
                                                // calculate time
                    drawSystem(t);              // draw system with Earth at this time
                }
            }.start();                          // start timer

        stagePrimary.show();                    // show scene
    }

    public static void main(String[] args) {
        Application.launch(args);           // launch the GUI
    }

}

以下是代码：

{{1}}

提前致谢。