JavaFX: How do I fill a table view with 2 different classes with the same super class

Question

I have 3 classes the first one is Library Item this is the super class. The other two classes are Book and Movie. When I want to fill my table view I want to make sure the correct property is called when populating the table view. I know it is easier to just call the director and author the same for ease of use, but I want to get it working for learning purposes. I have left out packages and imports for relevance.

LibraryItem class

public abstract class LibraryItem {
    private int itemCode;
    private String title;
    private boolean availability;
    private int memberIdentifier;
    private LocalDate dateLent;

    protected LibraryItem(int itemCode, String title, boolean availability, int memberIdentifier, LocalDate dateLent) {
        this.itemCode = itemCode;
        this.title = title;
        this.availability = availability;
        this.memberIdentifier = memberIdentifier;
        this.dateLent = dateLent;
    }

    public int getItemCode() {
        return itemCode;
    }

    public String getTitle() {
        return title;
    }

    public boolean isAvailability() {
        return availability;
    }

    public void setAvailability(boolean availability) {
        this.availability = availability;
    }

    public int getMemberIdentifier() {
        return memberIdentifier;
    }

    public void setMemberIdentifier(int memberIdentifier) {
        this.memberIdentifier = memberIdentifier;
    }

    public LocalDate getDateLent() {
        return dateLent;
    }

    public void setDateLent(LocalDate dateLent) {
        this.dateLent = dateLent;
    }
}

Book class

public class Book extends LibraryItem {
    private String author;

    protected Book(int itemCode, String title, boolean isLent, int memberIdentifier, LocalDate dateLent, String author) {
        super(itemCode, title, isLent, memberIdentifier, dateLent);
        this.author = author;
    }
}

Movie class

public class Movie extends LibraryItem {
    private String director;

    protected Movie(int itemCode, String title, boolean isLent, int memberIdentifier, LocalDate dateLent, String director) {
        super(itemCode, title, isLent, memberIdentifier, dateLent);
        this.director = director;
    }
}

I was thinking maybe there is some kind of check I can do for each row implemented so the correct value will be given,

This was my attempt:

public class CollectionController implements Initializable {
    @FXML
    private TableView<LibraryItem> libraryItemsTable;
    @FXML
    private TableColumn<LibraryItem, String> itemCodeColumn;
    @FXML
    private TableColumn<LibraryItem, String>  availableColumn;
    @FXML
    private TableColumn<LibraryItem, String>  titleColumn;
    @FXML
    private TableColumn<LibraryItem, String>  authorDirectorColumn;
    private LibraryService libraryService = new LibraryService();

    @Override
    public void initialize(URL location, ResourceBundle resources) {
        initializeTableView();
    }

    private void initializeTableView() {
        List<LibraryItem> libraryItems = libraryService.getLibraryItems();

        itemCodeColumn.setCellValueFactory(new PropertyValueFactory<>("itemCode"));
        availableColumn.setCellValueFactory(new PropertyValueFactory<>("availability"));
        titleColumn.setCellValueFactory(new PropertyValueFactory<>("title"));
        
        // implement here check for each new row
        if (checkIfBook(row))
            authorDirectorColumn.setCellValueFactory(new PropertyValueFactory<>("author"));
        else
            authorDirectorColumn.setCellValueFactory(new PropertyValueFactory<>("director"));
        //

        libraryItemsTable.getItems().addAll(libraryItems);
    }

Answer 1

If you follow the advice here and avoid the use of PropertyValueFactory, the solution becomes reasonably clear:

titleColumn.setCellValueFactory(data -> 
    new SimpleStringProperty(data.getValue().getTitle()));

authorDirectorColumn.setCellValueFactory(data -> {
    LibraryItem item = data.getValue();
    if (item instanceof Book book) {
        return new SimpleStringProperty(book.getAuthor());
    } else if (item instanceof Movie movie) {
        return new SimpleStringProperty(movie.getProducer());
    } else {
        return null ;
    }
});

Here's a complete example (I simplified the model classes for brevity, but retained enough to demonstrate the point):

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;

import java.io.IOException;

public class HelloApplication extends Application {
    @Override
    public void start(Stage stage) throws IOException {
        TableView<LibraryItem> table = new TableView<>();
        TableColumn<LibraryItem, String> titleColumn = new TableColumn<>("Title");
        TableColumn<LibraryItem, String> authorProducerColumn = new TableColumn<>("Author/Producer");
        table.getColumns().add(titleColumn);
        table.getColumns().add(authorProducerColumn);

        titleColumn.setCellValueFactory(data -> new SimpleStringProperty(data.getValue().getTitle()));

        authorProducerColumn.setCellValueFactory(data -> {
            LibraryItem item = data.getValue();
            if (item instanceof Book book) {
                return new SimpleStringProperty(book.getAuthor());
            } else if (item instanceof Movie movie) {
                return new SimpleStringProperty(movie.getProducer());
            } else return null ;
        });

        for (int i = 1 ; i <= 10 ; i++) {
            Book book = new Book("Book "+i, "Author "+i);
            Movie movie = new Movie("Movie "+i, "Producer "+i);
            table.getItems().addAll(book, movie);
        }

        BorderPane root = new BorderPane(table);
        Scene scene = new Scene(root);
        stage.setScene(scene);
        stage.show();
    }

    public class LibraryItem {
        private String title ;
        public LibraryItem(String title) {
            this.title = title ;
        }

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title;
        }
    }

    public class Movie extends LibraryItem {
        private String producer ;
        public Movie(String title, String producer) {
            super(title);
            this.producer = producer ;
        }

        public String getProducer() {
            return producer;
        }

        public void setProducer(String producer) {
            this.producer = producer;
        }
    }

    public class Book extends LibraryItem {
        private String author ;
        public Book(String title, String author) {
            super(title);
            this.author = author ;
        }

        public String getAuthor() {
            return author;
        }

        public void setAuthor(String author) {
            this.author = author;
        }
    }

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