同步组合盒Java秋千

Question

我想在Java swing 中创建同步组合框。当我选择其中一个省时，Kabupaten（区）组合框将包含所选省的所有地区。但是有一个问题。区组合盒仅选择省份组合框的第一个条目，当我在省份组合框中选择另一个条目时不会更改。为了获得完全同步的组合框，我需要做什么？ tia。

public void getProvince() {
    DBConnection dBConnection = new DBConnection();
    dBConnection.connection();
    Statement statement = null;
    try {
        statement = dBConnection.con.createStatement();
        String sql = "SELECT * FROM provinsi";
        ResultSet rs = statement.executeQuery(sql);
        while (rs.next()) {
            String provinceName = rs.getString("nama");
            String provinceId = rs.getString("id");
            provinsiCombo.addItem(provinceId);
        }
        dBConnection.con.close();
    } catch (SQLException e) {
        JOptionPane.showMessageDialog(null, "Gagal Terhubung");
    }
}

public void getKabupaten() {
    DBConnection dBConnection = new DBConnection();
    dBConnection.connection();
    Statement statement = null;
    try {
        statement = dBConnection.con.createStatement();
        String sql = "SELECT * FROM kabupaten WHERE id_prov = '"
                + provinsiCombo.getSelectedItem()
                + "'";
        ResultSet rs = statement.executeQuery(sql);
        while (rs.next()) {
            String kabupaten = rs.getString("nama");
            kabupatenCombo.addItem(kabupaten);
        }
        dBConnection.con.close();
    } catch (SQLException e) {
        JOptionPane.showMessageDialog(null, "Gagal Terhubung");
    }
}

Answer 1

如果要根据省份组合框的价值动态加载值到District Combobox，则需要使用侦听器。示例如下。最好将加载值从数据库移动到分开类，并在您的应用程序中使用加载值。

更新的代码：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ItemEvent;

public class SyncronizedComboboxExample extends JPanel
{
  String[] provinces= {"A","B","C"};
  String[] districtsForA = {"l","m","n"};
  String[] districtsForB = {"x","y","z"};
  String[] districtsForC = {"p","q","r"};

  public SyncronizedComboboxExample() {

    JComboBox provincesComboBox = new JComboBox(provinces);

    final DefaultComboBoxModel model = new DefaultComboBoxModel(districtsForA);
    JComboBox districtsComboBox = new JComboBox(model);

    provincesComboBox.addItemListener(e -> {
      if(e.getStateChange() == ItemEvent.SELECTED){
        DefaultComboBoxModel comboBoxModel;

          if(provincesComboBox.getSelectedItem().equals("A")){
            comboBoxModel = new DefaultComboBoxModel(districtsForA);
            districtsComboBox.setModel(comboBoxModel);
          }
          if(provincesComboBox.getSelectedItem().equals("B")){
            comboBoxModel = new DefaultComboBoxModel(districtsForB);
            districtsComboBox.setModel(comboBoxModel);
          }
          if(provincesComboBox.getSelectedItem().equals("C")){
            comboBoxModel = new DefaultComboBoxModel(districtsForC);
            districtsComboBox.setModel(comboBoxModel);
          }

      }
    });

    add(provincesComboBox, BorderLayout.PAGE_START);
    add(districtsComboBox, BorderLayout.AFTER_LAST_LINE);
    setBorder(BorderFactory.createEmptyBorder(20,20,20,20));
  }

  private static void createAndShowGUI() {
    //Create and set up the window.
    JFrame frame = new JFrame("CustomComboBoxDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Create and set up the content pane.
    JComponent newContentPane = new SyncronizedComboboxExample();
    newContentPane.setOpaque(true); //content panes must be opaque
    frame.setContentPane(newContentPane);

    //Display the window.
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    javax.swing.SwingUtilities.invokeLater(() -> createAndShowGUI());
  }

}