TableCell.setAlignment(..) and TreeTableCell.setAlignment(..) don't change the default state.

Neither

TableCell.setStyle("-fx-alignment: center-right;");

nor

.table-cell {
    -fx-alignment: center;
}

work.

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Pos;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.TableCell;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javafx.util.Callback;

public class TableViewApp extends Application {

    public Parent createContent() {
        
        final ObservableList<Person> data = FXCollections.observableArrayList(
            new Person("Jacob", "Smith"),
            new Person("Isabella", "Johnson"),
            new Person("Ethan", "Williams"),
            new Person("Emma", "Jones"),
            new Person("Michael", "Brown")
        );
        
        TableColumn<Person, String> firstNameCol = new TableColumn<>();
        firstNameCol.setText("First");
        firstNameCol.setCellValueFactory(new PropertyValueFactory("firstName"));
        firstNameCol.setCellFactory(new Callback<TableColumn<Person, String>, TableCell<Person, String>>() {
            public TableCell<Person, String> call(TableColumn<Person, String> p) {
                return new TableCell<Person, String>() {
                    {
                        this.setBackground(new Background(new BackgroundFill(Color.YELLOW, null, null)));
                        this.setAlignment(Pos.CENTER); // TODO doesn't work !!
                    }
                    @Override protected void updateItem(String item, boolean empty) {
                        super.updateItem(item, empty);
                        if (item == null || empty) {
                            this.setText("");
                        }
                        else {
                            this.setText(item);
                        }
                    }
                };
            }
        });
                
        TableColumn<Person, String> lastNameCol = new TableColumn<>();
        lastNameCol.setText("Last");
        lastNameCol.setCellValueFactory(new PropertyValueFactory("lastName"));
        lastNameCol.setCellFactory(new Callback<TableColumn<Person, String>, TableCell<Person, String>>() {
            public TableCell<Person, String> call(TableColumn<Person, String> p) {
                return new TableCell<Person, String>() {
                    {
                        this.setBackground(new Background(new BackgroundFill(Color.ORANGE, null, null)));
                        this.setAlignment(Pos.CENTER_RIGHT); // TODO doesn't work !!
                    }
                    @Override protected void updateItem(String item, boolean empty) {
                        super.updateItem(item, empty);
                        if (item == null || empty) {
                            this.setText("");
                        }
                        else {
                            this.setText(item);
                            System.out.println("Alignment = " + this.getAlignment());
                        }
                    }
                };
            }
        });
        
        TableView<Person> tableView = new TableView<>();
        tableView.setItems(data);
        tableView.getColumns().addAll(firstNameCol, lastNameCol);
        
        return tableView;
    }
   
    @Override public void start(Stage primaryStage) throws Exception {
        primaryStage.setScene(new Scene(createContent()));
        primaryStage.show();
    }

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

        private StringProperty firstName;
        private StringProperty lastName;

        public Person(String fName, String lName) {
            this.firstName = new SimpleStringProperty(fName);
            this.lastName = new SimpleStringProperty(lName);
        }

        public StringProperty firstNameProperty() {
            return firstName;
        }

        public StringProperty lastNameProperty() {
            return lastName;
        }
    }
}