Question

所以我正在编写一个包含这段代码的程序

final ListModel listModel = new DefaultListModel();
JButton btnBuscar = new JButton("Buscar");
btnBuscar.addActionListener(new ActionListener() {
    public void actionPerformed(ActionEvent e) {
        listModel = MySQL("SELECT * FROM catalogos WHERE id = '" +
                           searchField.getText() +
                           "' OR name LIKE '%" +
                           searchField.getText() +
                            "%' OR keywords LIKE '%" +
                           searchField.getText() + "%'", "SELECT");             
    }
});

btnBuscar.setBounds(336, 11, 89, 23);
searchPanel.add(btnBuscar);

JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(10, 44, 316, 185);
searchPanel.add(scrollPane);
JList list = new JList(listModel);
scrollPane.setViewportView(list);

正如您所看到的，我创建了一个ListModel变量，然后想要在按下按钮时使用它。函数MySQL返回一个listModel。

然后，我想创建一个列表，并在listmodel中为其提供元素。这段代码有什么问题？

Answer 1

请阅读JDBC(TM) Database Access
尝试examples

示例的快捷方式

    try {
        String sqlSyntax = "SELECT * FROM ........";
        Statement stmt = myDbConnection.createStatement();
        ResultSet rsts = stmt.executeQuery(sqlSyntax);
        while (rsts.next()) {
            final String str = rsts.getString(1); // or another data types
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    listModel.add(str.trim());
                }
            });
        }
    } catch (SQLException ex) {
        // exeption handling
    } finally {
        try {
            rsts.close();
            stmt.close();
        } catch (SQLException ex) {
            // not important  
        }
    }

Answer 2

除了SQL问题，您正在尝试重新分配final变量。您应该使listModel字段（实例变量）而不是最终的局部变量，以便您的actionListener可以访问并更改它。

而不是

public class YourClassName {
  public ? yourMethodName() {
    final ListModel listModel = new DefaultListMode();
    JButton btnBuscar = new JButton("Buscar");
    ...

你会写

public class YourClassName {
  private ListModel listModel = new DefaultListModel();
  public ? yourMethodName() {
    JButton btnBuscar = ...

按下按钮定义listModel

2 个答案: