Create Nodes within Loop - javafx

Question

Note: this is an updatet version of the initial question.
Whats now beeing asked is how I can get access to the values of a certain row for calculations purposes. For example how can I calculate the difference betweeen values of the expensesColumn and the earningsColumn? (Because there was to much code within my questions, I deleted most of the imports)
package application;
import javafx.application.Application;
import javafx.stage.Stage;
public class Main extends Application {
#Override
public void start(Stage primaryStage) {
try {Table.create(primaryStage);}
catch(Exception e) {e.printStackTrace();}
}
public static void main(String[] args) {
launch(args);
}
}
package application;
public class UserJava {
private String member;
private double expenses;
private double earnings;
//Getter und Setter
public String getMember() {
return member;
}
public void setMember(String member) {
this.member = member;
}
public double getExpenses() {
return expenses;
}
public void setExpenses(double expenses) {
this.expenses = expenses;
}
public double getEarnings() {
return earnings;
}
public void setEarnings(double earnings) {
this.earnings = earnings;
}
}
package application;
import javafx.stage.Stage;
public class Table {
static TableView<UserJava> table;
public static void create (Stage primaryStage){
try {
GridPane primarygridpane = new GridPane();
HBox hboxTable = new HBox(10);
//Definition der Tabelle
TableColumn<UserJava, String> userColumn = new TableColumn<>("Name");
userColumn.setCellValueFactory(new PropertyValueFactory<>("member"));
userColumn.setMinWidth(200);
TableColumn<UserJava, Double> expensesColumn = new TableColumn<>("Ausgaben");
expensesColumn.setCellValueFactory(new PropertyValueFactory<>("expenses"));
expensesColumn.setMinWidth(100);
TableColumn<UserJava, Double> earningsColumn = new TableColumn<>("Pfand");
earningsColumn.setCellValueFactory(new PropertyValueFactory<>("earnings"));
earningsColumn.setMinWidth(100);
table = new TableView<>();
table.getColumns().addAll(userColumn, expensesColumn, earningsColumn);
TextField tfMember = new TextField();
tfMember.setMinWidth(200);
tfMember.setPromptText("Name");
TextField tfExpenses = new TextField();
tfExpenses.setMinWidth(100);
tfExpenses.setPromptText("Ausgaben");
TextField tfEarnings = new TextField();
tfEarnings.setMinWidth(100);
tfEarnings.setPromptText("Pfand");
Button btnAdd = new Button("Hinzufügen");
Button btnDelete = new Button("Löschen");
hboxTable.getChildren().addAll(tfMember, tfExpenses, tfEarnings, btnAdd, btnDelete);
table.setEditable(true);
userColumn.setCellFactory(TextFieldTableCell.forTableColumn());
// table.setItems(getUser());
//Sonstiges
Scene scene = new Scene(primarygridpane,725,400);
Text titel = new Text("Application");
titel.setFont(Font.font("Arial", FontWeight.BOLD, 28));
primarygridpane.add(titel, 0, 0, 2, 1);
primarygridpane.add(table, 0, 2);
primarygridpane.add(hboxTable, 0, 3);
// scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.show();
//Funktionen
btnAdd.setOnAction(new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent e) {
try {
UserJava user = new UserJava();
user.setMember(tfMember.getText());
user.setExpenses(Double.parseDouble(tfExpenses.getText()));
user.setEarnings(Double.parseDouble(tfEarnings.getText()));
table.getItems().add(user);
tfMember.clear();
tfExpenses.clear();
tfEarnings.clear();
System.out.println(table.getItems());
}
catch (NumberFormatException Ausnahme) {}
}
});
btnDelete.setOnAction(new EventHandler<ActionEvent>(){
#Override
public void handle(ActionEvent e) {
try {
ObservableList<UserJava> userSelected, userAll;
userAll = table.getItems();
userSelected = table.getSelectionModel().getSelectedItems();
userSelected.forEach(userAll::remove);
System.out.println();
}
catch (java.util.NoSuchElementException Ausnahme) {}
}
});
}
catch (Exception e) {e.printStackTrace();}
}
public ObservableList<UserJava> getUser(){
ObservableList<UserJava> user = FXCollections.observableArrayList();
user.add(new UserJava());
return user;
}
public void changeCell(CellEditEvent<?, ?> ediditedCell) {
UserJava personSelected = table.getSelectionModel().getSelectedItem();
personSelected.setMember(ediditedCell.getNewValue().toString());
}
}