GUI中國家和城市的動態列表

Question

我想爲國家和城市創建兩個下拉列表。因此，如果用戶從下拉列表中選擇一個國家，則應該自動刷新另一個下拉列表以顯示其相應的城市。

public void fillCombo(){ 
     String sql = " select * from sallytimes.table_name " ; 
     try { 
      ps = con.prepareStatement(sql); 
      rs = ps.executeQuery(sql); 

      while (rs.next()){ 
       jComboBox_Country.addItem(rs.getString("_id")); 
       jComboBox_City.addItem(rs.getString("city"));  
      } 
     } catch (SQLException ex) { 
      Logger.getLogger(Location.class.getName()).log(Level.SEVERE, null, ex); 
     } 
} 

我該如何處理？

Answer 1

你需要一個ActionListener添加到第一個組合框，當一個項目被選中來執行操作。在ActionListener中，您想用新數據替換第二個組合框的模型。

喜歡的東西：

import java.awt.*; 
import java.awt.event.*; 
import java.util.*; 
import javax.swing.*; 
import javax.swing.plaf.basic.*; 

public class ComboBoxTwo extends JPanel implements ActionListener 
{ 
    private JComboBox<String> mainComboBox; 
    private JComboBox<String> subComboBox; 
    private Hashtable<String, String[]> subItems = new Hashtable<String, String[]>(); 

    public ComboBoxTwo() 
    { 
     String[] items = { "Select Item", "Color", "Shape", "Fruit" }; 
     mainComboBox = new JComboBox<String>(items); 
     mainComboBox.addActionListener(this); 

     // prevent action events from being fired when the up/down arrow keys are used 
     mainComboBox.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE); 
     add(mainComboBox); 

     // Create sub combo box with multiple models 

     subComboBox = new JComboBox<String>(); 
     subComboBox.setPrototypeDisplayValue("XXXXXXXXXX"); // JDK1.4 
     add(subComboBox); 

     JButton arrow = SwingUtils.getDescendantOfType(JButton.class, subComboBox, "Text", ""); 
     Dimension d = arrow.getPreferredSize(); 
     System.out.println(arrow.getClass()); 
     System.out.println(d); 
     d.width = 35; 
     arrow.setPreferredSize(d); 

     String[] subItems1 = { "Select Color", "Red", "Blue", "Green" }; 
     subItems.put(items[1], subItems1); 

     String[] subItems2 = { "Select Shape", "Circle", "Square", "Triangle" }; 
     subItems.put(items[2], subItems2); 

     String[] subItems3 = { "Select Fruit", "Apple", "Orange", "Banana" }; 
     subItems.put(items[3], subItems3); 
    } 

    public void actionPerformed(ActionEvent e) 
    { 
     String item = (String)mainComboBox.getSelectedItem(); 
     Object o = subItems.get(item); 

     if (o == null) 
     { 
      subComboBox.setModel(new DefaultComboBoxModel()); 
     } 
     else 
     { 
      subComboBox.setModel(new DefaultComboBoxModel((String[])o)); 
     } 
    } 

    private static void createAndShowUI() 
    { 
     try 
     { 
//   UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
     } 
     catch (Exception e) { } 
     JFrame frame = new JFrame("SSCCE"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.add(new ComboBoxTwo()); 
     frame.setLocationByPlatform(true); 
     frame.pack(); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) 
    { 
     EventQueue.invokeLater(new Runnable() 
     { 
      public void run() 
      { 
       createAndShowUI(); 
      } 
     }); 
    } 
} 

所以，你會需要修改的ActionListener的代碼即可獲得基於所選國家數據庫中的城市。