如何解决NullPointerException异常用于填充在JavaFX的控制器？ [重复]

Question

这个问题已经在这里有一个答案：

• What is a NullPointerException, and how do I fix it? 12个回答

全面建设的JavaFX应用程序，使用一个表来填充客户名称和ID，然后加入一旦客户的名字被从表中选择一个启动另一种形式的按钮。我得到的错误。

我曾试图改变名称populateCustomerAllName，试图改变返回类型

 @FXML 
public void handleAddButton() {
    if(customerAllTable.getSelectionModel().getSelectedItem() != null) {
        selectedCustomer = customerAllTable.getSelectionModel().getSelectedItem();
    } else {
        return;
    }
    Dialog<ButtonType> dialog = new Dialog();
    dialog.initOwner(appointmentMain.getScene().getWindow());
    FXMLLoader fxmlLoader = new FXMLLoader();
    fxmlLoader.setLocation(getClass().getResource("AppointmentAdd.fxml"));
    try {
        dialog.getDialogPane().setContent(fxmlLoader.load());
    } catch(IOException e) {
        System.out.println("AppointmentAdd Error: " + e.getMessage());
    }
    ButtonType save = new ButtonType("Save", ButtonBar.ButtonData.OK_DONE);
    dialog.getDialogPane().getButtonTypes().add(save);
    dialog.getDialogPane().getButtonTypes().add(ButtonType.CANCEL);
    AppointmentAddController controller = fxmlLoader.getController();


//error with populating .getCustomerAllName         controller.populateCustomerAllName(selectedCustomer.getCustomerAllName());
    dialog.showAndWait().ifPresent((response -> {
        if(response == save) {
            if(controller.handleAddAppointment(selectedCustomer.getCustomerAllId())) {
                monthAptTable.setItems(AppointmentDB.getMonthlyAppointments(selectedCustomer.getCustomerAllId()));
                weekAptTable.setItems(AppointmentDB.getWeeklyAppoinments(selectedCustomer.getCustomerAllId()));
            } else {
                Alert alert = new Alert(Alert.AlertType.ERROR);
                alert.setTitle("Error");
                alert.setHeaderText("Add Appointment Error");
                alert.setContentText(controller.displayErrors());
                alert.showAndWait().ifPresent((response2 -> {
                    if(response2 == ButtonType.OK) {
                        handleAddButton();
                    }
                }));
            }
        }
    }));







public void populateCustomerAllName(String name) {
    customerAllName.setText(name);
}







Caused by: java.lang.NullPointerException
at   views.AppointmentAddController.populateCustomerAllName(AppointmentAddController.java:170)
at views.AppointmentMainController.handleAddButton(AppointmentMainController.java:155)

预期结果都在addAppointment按钮客户名称填充到客户现场，当点击。

Answer 1

需要更新FXML标签FX：ID = “customerAllName”