JavaFX中FXMLLoader递归加载致空指针异常求助

我正在开发大学作业项目——一款名为RogerBook的JavaFX社交应用，当前遇到FXMLLoader递归加载导致LoadException，以及后续PostView类实例变量的空指针异常问题。

PostView类继承自AnchorPane，既是帖子展示组件，也是对应FXML文件的控制器。每次执行new PostView();时都会触发递归加载错误，错误栈如下：

at javafx.fxml@21/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2722)
    at javafx.fxml@21/javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:946)
    at javafx.fxml@21/javafx.fxml.FXMLLoader$RootElement.processAttribute(FXMLLoader.java:1302)
    at javafx.fxml@21/javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:230)
    at javafx.fxml@21/javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:757)
    at javafx.fxml@21/javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2853)
    at javafx.fxml@21/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2649)
    at javafx.fxml@21/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2563)
    at javafx.fxml@21/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2531)
    at com.rogerbook.ui/com.rogerbook.ui.PostView.<init>(PostView.java:31)

错误发生后，PostView类中所有实例变量都会抛出空指针异常，相关代码如下：

PostView类（省略导入语句） #

package com.rogerbook.ui;

public class PostView extends AnchorPane {
    PicPost post;
    @FXML
    private ImageView imageView = new ImageView();
    @FXML
    private Label Username = new Label();
    @FXML
    private Label Title = new Label();

    public PostView(PicPost post){
        this();
        this.post = post;
        initializePostView();
    }

    public PostView() {
        FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("Post.fxml"));
        fxmlLoader.setRoot(this);
        try{
            fxmlLoader.load();
        }catch(IOException e){
            e.printStackTrace();
        }
    }

    private void initializePostView() {
        if (post != null) {
            imageView.setImage(post.getImage());
            Username.setText(post.getAuthor().getProfile().getUserName());
            Title.setText(post.getTitle());
        }
    }
}

主启动类 #

public class HelloApplication extends Application {

    @Override
    public void start(Stage stage) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("hello-view.fxml"));
        Scene scene = new Scene(fxmlLoader.load());
        stage.setTitle("Hello!");
        stage.setScene(scene);
        stage.show();
    }

    public static void main(String[] args) {
        launch();
    }
}

注册页面控制器（HelloController） #

public class HelloController {

    private Stage stage;
    private Scene scene;
    private Parent root;

    @FXML
    private TextField username;
    @FXML
    public TextField password;
    @FXML
    public TextField name;
    @FXML
    private TextField password2;
    @FXML
    private Label errmsg;

    @FXML
    public void switchToHome(ActionEvent event) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("scenefeedpage.fxml"));
        stage = (Stage)((Node)event.getSource()).getScene().getWindow();
        root = fxmlLoader.load();
        scene = new Scene(root);
        stage.setScene(scene);
        stage.show();
    }

    @FXML
    public void onSignup(ActionEvent event) throws IOException {
        System.out.println(password.getText());
        if(password.getText().isEmpty() || username.getText().isEmpty() || name.getText().isEmpty() || password2.getText().isEmpty()){
            errmsg.setText("Please fill all the fields");
            return;
        }
        if(password.getText().equals(password2.getText())){
            if(Roger.signup(username.getText().toLowerCase().strip(), password.getText())) {
                switchToHome(event);
            }
            else {
                errmsg.setText("Incorrect Password, or user does not exist");
            }
        }
        else{
            errmsg.setText("Passwords do not match");
        }
    }
}

Feed页面控制器（FeedController） #

public class FeedController implements Initializable {
    private Stage stage;
    private Scene scene;
    private Parent root;
    Post post;

    @FXML
    ImageView imageView;

    @FXML
    VBox view;

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        System.out.println("Initializing Feed");
        ArrayList<Post> feed = Roger.getFeed();
        System.out.println("Feed done");

        feed.add(new PicPost("Hi", new Image("com/RogerBook/ui/R.png"), new User("maro", "aa")));

        //PostView postView1 = new PostView((PicPost)feed.get(0));
        post = feed.get(0);
        view.getChildren().add(new PostView((PicPost)post));
        //view.getChildren().add(new PostView());
    }

    public void ViewPost(ActionEvent event) throws IOException {
        FXMLLoader fxmlLoader = new FXMLLoader(HelloApplication.class.getResource("Post.fxml"));
        stage = (Stage)((Node)event.getSource()).getScene().getWindow();
        root = fxmlLoader.load();
        scene = new Scene(root);
        stage.setScene(scene);
        stage.show();
    }
}

应用流程：启动后进入注册页面，注册完成跳转至Feed页面，FeedController向VBox中添加PostView组件时触发上述问题。已排查数小时仍未解决，寻求帮助。

内容的提问来源于stack exchange，提问作者TheMaro