java - 为什么这个 JList 不更新以显示 ArrayList 属性

Question

下面有一个方法，在调用时应该显示列表中 arrayList 元素的属性:

public void updateList(){

    DefaultListModel<String> model = (DefaultListModel<String>)jCustomerList.getModel();

        for(User user: theUserList.Users){        
        model.addElement(user.getName());   

        jCustomerList.setModel(model); 

        }
}

但是，当调用它时，会出现以下错误:

线程“AWT-EventQueue-0”中的异常 java.lang.ClassCastException:supermarketiteration2.ShopJFrame$63 无法转换为 javax.swing.DefaultListModel

如何解决这个问题？

编辑**

模型已全局化，如下所示，但是现在实例化模型时出现错误:

public class ShopJFrame extends javax.swing.JFrame {
private UserList theUserList;
private User currentCustomer;
private Customer castedCustomer;
private SupplierList theSupplierList;
private DeliveryCompanyList theDeliveryCompanyList;
private ProductList theProductList;
private Product selectedProduct;
private Supplier aSupplier;
private DeliveryCompany aDeliveryCompany;
//private JList jCustomerList;

private java.awt.Component jTabInMemory1;
private java.awt.Component jTabInMemory2;
private java.awt.Component jTabInMemory3;
private java.awt.Component jTabInMemory4;
private java.awt.Component jTabInMemory5;
private java.awt.Component jTabInMemory6;

DefaultListModel<String> model;




    public ShopJFrame() throws IOException, FileNotFoundException, ParseException {
        initComponents();
    theUserList = new UserList();
    User currentCustomer = new Customer();
    Customer castedCustomer = null;
    theDeliveryCompanyList = new DeliveryCompanyList();
    aDeliveryCompany = new DeliveryCompany();
    theSupplierList = new SupplierList();
    aSupplier = new Supplier();
    theProductList = new ProductList();

    jTabInMemory1 = jMainTabbedPane.getComponent(1);//PRODUCTS
    jMainTabbedPane.remove(1);
    jTabInMemory2 = jMainTabbedPane.getComponent(1);//REORDER
    jMainTabbedPane.remove(1);
    jTabInMemory3 = jMainTabbedPane.getComponent(1);//SUPPLY CHAIN
    jMainTabbedPane.remove(1);
    jTabInMemory4 = jMainTabbedPane.getComponent(1);//CATALOGUE
    jMainTabbedPane.remove(1);
    jTabInMemory5 = jMainTabbedPane.getComponent(1);//MY ACCOUNT
    jMainTabbedPane.remove(1);
    jTabInMemory6 = jMainTabbedPane.getComponent(1);//MY ACCOUNT
    jMainTabbedPane.remove(1);

    theProductList.loadFromFile(theProductList.getFilename());
    theSupplierList.loadFromFile();
    theDeliveryCompanyList.loadFromFile();
    theUserList.loadFromFile();
    theProductList.displayReorders(jProductReorderTextArea);

    this.updateComboBox("Supplier");
    this.updateComboBox("Delivery Company");
    this.updateComboBox("Products");
    model = (DefaultListModel<String>)jCustomerList.getModel();
    jCustomerList.setModel(model); 

Answer 1

正在 Swing model被传递给 JComponent。

DefaultListModel<String> model = new DefaultListModel<>();
jCustomerList = new JList<String>(model);

model.addElement("Albert Einstein");
...

_(后来的 JavaFX 有可观察数据类型，有点像您想要的绑定(bind)。)_

现在不应创建新的 JList 或 ListModel。

public void updateList() {

    DefaultListModel<String> model = (DefaultListModel<>)jCustomerList.getModel();
    model.addElement("Madame Curie");
}