Вы получаете ошибку String, потому что то, что вы пишете, когда a ComboBox доступно для редактирования, это TextField, которое возвращает String. Когда вы снимаете фокус с этого поля (например, нажимаете Alt + Tab, щелкаете по другому полю и т. Д. c.) Или нажимаете «Enter», система пытается добавить этот String в список ComboBox, но поскольку указанный ComboBox относится к типу Customer, он не может.
Чтобы справиться с этим, вам нужно использовать StringConverter. См. this о том, как этого добиться.
EDIT :
Попробовав, я нашел this . Мне удалось адаптировать его к вашему случаю.
package sample;
public class Customer {
private int id;
private String name;
public Customer(int id, String name) {
this.id = id;
this.name = name;
}
// Getters & Setters
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
// You don't need to override the toString() method for this
}
CustomerConverter - это нестандартный Converter класс.
package sample;
import javafx.util.StringConverter;
public class CustomerConverter extends StringConverter<Customer> {
private int customerId;
// Method to convert a Customer-Object to a String
@Override
public String toString(Customer customer)
{
return customer == null? null : customer.getName();
}
// Method to convert a String to a Customer-Object
@Override
public Customer fromString(String string) {
Customer customer = null;
if (string == null) {
return customer;
}
customer = new Customer(customerId, string);
return customer;
}
public void setCustomerId(int customerId) {
this.customerId = customerId;
}
}
Controller класс из FXML.
package sample;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.ComboBox;
import javafx.scene.input.KeyCode;
import java.net.URL;
import java.util.ArrayList;
import java.util.ResourceBundle;
public class Controller implements Initializable {
@FXML
ComboBox<Customer> selectionBox;
private ArrayList<Customer> customerList = new ArrayList<Customer>();
@Override
public void initialize(URL url, ResourceBundle resourceBundle) {
selectionBox.getItems().addAll(addItemsToComboBox());
selectionBox.setConverter(new CustomerConverter());
// This will add the New Customer object from the ComboBox's TextField to the list of Customers
// on pressing ENTER
selectionBox.setOnKeyPressed(e -> {
if (e.getCode() == KeyCode.ENTER) {
// To create a new ID, get the total number of items in the ArrayList of Customer objects
// and add 1.
// You can also call your Order method here or read the ArrayList and get the Customer from there.
addCustomer(new Customer(customerList.size() + 1, selectionBox.getEditor().getText()));
}
});
// By default, when the ComboBox TextField is un-focused, the system will try to add it to the list
// You can tell by the 'System.out.print's in the two methods below this one, but by doing things this
// way, it will not be able to because your ComboBox is populated by the ArrayList.
// If you still want to add Customer Objects when it's un-focused, uncomment this part.
/*selectionBox.focusedProperty().addListener(new ChangeListener<Boolean>() {
@Override
public void changed(ObservableValue<? extends Boolean> observableValue, Boolean outOfFocus, Boolean onFocus) {
if (outOfFocus) {
// You can also call your Order method here or read the ArrayList and get the Customer from there.
addCustomer(new Customer(customerList.size() + 1, selectionBox.getEditor().getText()));
}
}
});*/
// Handles the selected Customer item from the ComboBox.
selectionBox.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<Customer>() {
public void changed(ObservableValue<? extends Customer> ov,
final Customer oldvalue, final Customer newvalue) {
// This IF check exists, because the first time you select an item,
// there will be no old item that has been previously selected.
// If this check is removed, you'll get a NullPointerException when trying to get values from
// 'oldvalue' Object.
if (oldvalue != null){
System.out.println("Customer changed from: " + oldvalue.getName()
+ " with ID: " +oldvalue.getId() + " to: "
+ newvalue.getName() + " with ID: " + newvalue.getId());
}
else {
System.out.println("New customer has been selected who's name is: "
+ newvalue.getName() + " with ID: " + newvalue.getId());
}
}
});
// Handles the selected Customer item index from the ComboBox.
selectionBox.getSelectionModel().selectedIndexProperty().addListener(new ChangeListener<Number>()
{
public void changed(ObservableValue<? extends Number> ov,
final Number oldvalue, final Number newvalue) {
System.out.println("Old ComboBox Index: " + oldvalue + " changed to: " + newvalue);
}
});
}
// Adds a new Customer Object to the list.
// Clears the ComboBox and re-populates it.
public void addCustomer(Customer customer) {
customerList.add(customer);
selectionBox.getItems().clear();
selectionBox.getItems().addAll(customerList);
}
// Adds the initial Customer Objects for testing purposes.
public ArrayList<Customer> addItemsToComboBox(){
customerList = new ArrayList<Customer>();
customerList.add(new Customer(1,"John"));
customerList.add(new Customer(2,"Mark"));
customerList.add(new Customer(3,"Roger"));
customerList.add(new Customer(4,"David"));
customerList.add(new Customer(5,"Rick"));
return customerList;
}
}