Java GUI使用一个Jtextfield同时输入文本和数字

Question

我有一个带有一些方法的DAO类，例如从数据库中按ID和按名称获取雇员。这些方法工作正常。

这是我的代码

public class EmployeeApp extends JFrame {
private JPanel panelMain;
private JButton searchButton;
private JScrollPane scrollPane;
private JTextField idTextField;
private JLabel lastNameLabel;

private EmployeesDao employeesDao;


public EmployeeApp() {

    // create the DAO
    try {
        employeesDao = new EmployeesDao();
    } catch (Exception exc) {
        JOptionPane.showMessageDialog(this, "Error: " + exc, "Error", JOptionPane.ERROR_MESSAGE);
    }

    searchButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {

            try {
                String searchValue = idTextField.getText();

                List<Employee> employees;

                if (searchValue != null && searchValue.trim().length() > 0) {
                    employees = employeesDao.searchEmployees(searchValue);
                } else {
                    employees = employeesDao.getAllEmployees();
                }
                for (Employee temp : employees) {
                    System.out.println(temp);
                }

            } catch (Exception exc) {
                JOptionPane.showMessageDialog(EmployeeApp.this, "Error: " + exc, "Error", JOptionPane.ERROR_MESSAGE);

            }

        }
    });
}

public static void main(String[] args) {
    JFrame frame = new JFrame("EmployeeApp");
    frame.setContentPane(new EmployeeApp().panelMain);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
}}

编辑：我试图修改try/catch块，现在当我在JTextField中输入一个数字时，getEmployeeById方法可以正常工作。但是，当输入字符串时，我会得到一个NumberFormatException。

        searchButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            String searchValue = idTextField.getText();
            List<Employee> employees;
            Employee employee;

            try {
                int numValue = Integer.parseInt(searchValue);
                employee = employeesDao.getEmployeeById(numValue);
                System.out.println(employee);

                if (searchValue != null && searchValue.trim().length() > 0) {
                    employees = employeesDao.searchEmployees(searchValue);
                }

                else {
                    employees = employeesDao.getAllEmployees();
                }
                for (Employee temp : employees) {
                    System.out.println(temp);
                }

            } catch (Exception exc) {
                JOptionPane.showMessageDialog(EmployeeApp.this, "Error: " + exc, "Error", JOptionPane.ERROR_MESSAGE);

            }

        }
    });

Answer 1

我们建议您从catch块中获取错误消息，并在那里执行更有用的操作。如果输入了catch块，则您知道idTextField没有保存有效的数值数据，您应该使用文本提取您的数据，使用名称或文本数据，而不是数值数据。类似于：

    @Override
    public void actionPerformed(ActionEvent e) {
        String idText = idTextField.getText().trim();
        try {
            int value = Integer.parseInt(idText);

            // if we have reached this line, then idText is numeric

            // code here to get Employee by value number

        } catch (NumberFormatException e1) {

            // don't show an error message here!
            // If we get here we know that idText is **not** numeric

            // code here to to get Employee by name using idText
        }
    }

但我自己不喜欢这种胡闹，相反，我会努力使我的代码更好地防止白痴。您可以使用JRadioButtons允许用户使用文本或数值进行数据提取，然后对JTextField进行调整，使其在用户选择数值选项时不接受文本。例如，可以通过在JTextField的文档上设置和移除DocumentFilter来实现。