使用泛型类型构造一个ObservableList

Question

I'm trying to extend the JavaFX TableView class so that I can literally pass an Entity class to it and it will display all the saved objects for that class. I'm able to make it work like this but I want my custom class to be generic enough to just accept a Class variable and take care of the rest :

private void showSuppliers()
{
    tabPane.getTabs().stream().filter((tab) -> (tab.getText().compareTo("Fournisseurs") == 0)).map((tab) -> (VBox)tab.getContent()).forEachOrdered((vBox) -> 
    {
        TableView<Supplier> table = new TableView<>();

        TableColumn nameColumn = new TableColumn("Nom");
        nameColumn.setCellValueFactory(new PropertyValueFactory<>("name"));

        TableColumn addressColumn = new TableColumn("Addresse");
        addressColumn.setCellValueFactory(new PropertyValueFactory<>("address"));

        TableColumn contactColumn = new TableColumn("Contact");
        contactColumn.setCellValueFactory(new PropertyValueFactory<>("contactPerson"));

        TableColumn phoneNumberColumn = new TableColumn("Téléphone");
        phoneNumberColumn.setCellValueFactory(new PropertyValueFactory<>("phoneNumber"));

        TableColumn emailColumn = new TableColumn("Courriel");
        emailColumn.setCellValueFactory(new PropertyValueFactory<>("emailAddress"));

        TableColumn creationDateColumn = new TableColumn("Date de création");
        creationDateColumn.setCellValueFactory(new PropertyValueFactory<>("enteredDate"));

        table.getColumns().addAll(nameColumn, addressColumn, contactColumn, phoneNumberColumn, emailColumn, creationDateColumn);

        ObservableList<Supplier> suppliers = FXCollections.observableArrayList(supplierService.findAll());
        table.setItems(suppliers);

        vBox.getChildren().add(table);
    });
}

Again, the above method works perfectly but I would have to repeat it for every table listing different data which i want to avoid. My plan is to extend TableView with a generic type, something like this :

public class EntityTable<T> extends TableView<T>
{
    private final Class<T> entityClass;

    public EntityTable(Class<T> entityClass) 
    {
        this.entityClass = entityClass;

        init();
    }

    private void init()
    {
        for (Field field : entityClass.getDeclaredFields())
        {
            if ((field.getType() != Set.class) && (field.getName().compareTo("id") != 0))
            {
                TableColumn column = new TableColumn(field.getName());
                column.setCellValueFactory(new PropertyValueFactory<>(field.getName()));

                getColumns().add(column);
            }
        }
    }
}

Adding the columns is not a problem as you can see. What I don't understand is how to use my T to make something like this ObservableList :

ObservableList<Supplier> suppliers = FXCollections.observableArrayList(supplierService.findAll());

I tried just replacing <Supplier> by <T> or <Class<T>> and that does not seem to be valid. I learned Java way back when this stuff barely even existed and the information i found online about it is a bit confusing to be honest.

How can I construct my list using my T variable as a type?

Thanks!

Answer 1

Well, this was simple, I just removed it altogether! Here is the end result, just pass an entity class and a list and the table takes care of the rest!

public class EntityTable<T> extends TableView<T>
{
    private final Class<T> entityClass;

    private final List<T> entityList;

    public EntityTable(Class<T> entityClass, List<T> entityList) 
    {
        this.entityClass = entityClass;
        this.entityList = entityList;

        init();
    }

    private void init()
    {
        for (Field field : entityClass.getDeclaredFields())
        {
            if ((field.getType() != Set.class) && (field.getName().compareTo("id") != 0))
            {
                TableColumn column = new TableColumn(field.getName());
                column.setCellValueFactory(new PropertyValueFactory<>(field.getName()));

                getColumns().add(column);
            }
        }

        ObservableList list = FXCollections.observableArrayList(entityList);
        setItems(list);
    }
}

The downside is that this will display column headers with the actual property name in the class (not always very user friendly). Any suggestions to put something nicer in the column headers automatically will be welcome!

EDIT

For my column names, i ended up creating a custom annotation called FriendlyName with just a value parameter. I now populate the column headers like this :

FriendlyName friendlyName = field.getAnnotation(FriendlyName.class);

TableColumn column = new TableColumn(friendlyName.value());