如何建立三个下拉列表之间的连动关系？在线等侯！！！

Question

我在JBuilder中，用jComboBox做过这个，是两个的，三个应该也是一样的。下面是我的做法，不知道跟你情况一样不，给你参考一下。
添加jComboBox1的ActionPerformed事件，在该方法先判断选定的Item即jComboBox1.getSelectedItem().toString()是否变化，若变化了，则根据对jComboBox1的选择，查询出要在jComboBox2中显示的内容，然后先用jComboBox2.removeAllItems()方法删掉下一个相关下拉列表中的原有内容，再用jComboBox2.addItem()方法加入新的内容。
代码如下：
void jComboBox1_actionPerformed(ActionEvent e) {
    if(selectedItem != jComboBox1.getSelectedItem().toString()){
      selectedItem = jComboBox1.getSelectedItem().toString();
      jComboBox2.removeAllItems();
      parameterRow1.setString("queryColumn",selectedItem);
      queryDataSet1.refresh();
      queryDataSet1.open();
      rowCount1 = queryDataSet1.getRowCount();
      for(int i = 0;i < rowCount1;i++){
        jComboBox2.addItem(queryDataSet2.getString("displayColumn"));
        queryDataSet1.next();
      }
    }
}
再增加一个jComboBox也与此类似，只要在jComboBox2的ActionPerformed事件中做与上面类似的处理就可以了。

Answer 1

http://www.csdn.net/Expert/TopicView1.asp?id=949181

Answer 2

我写了一个简单的例子，就用于连动显示省、市和县的关系，如下，你试运行一下，但愿对你有所帮助：
import javax.swing.*;
import java.util.*;
import java.awt.event.*;
import java.awt.*;public class Control3Combox extends JFrame {
  private JComboBox comb1 ;
  private JComboBox comb2 ;
  private JComboBox comb3 ;  private Vector provinces = new Vector();
  public Control3Combox() {
//      comb1 = new JComboBox();
//      comb2 = new JComboBox();
//      comb3 = new JcomboBox();
     jb_init();
  }  private void jb_init(){
      // create the first province
      Province pro = new Province("Bei Jing");
      City  city1 = new City("海淀", pro);
      County coun1 = new County("hd1", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("hd2", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("hd3",city1);
      city1.addCounty(coun1) ;
      pro.addCity(city1) ;
      city1 = new City("chaoyang", pro);
      coun1 = new County("cy1", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("cy2",city1);
      city1.addCounty(coun1) ;
      pro.addCity(city1) ;
      city1 = new City("丰台", pro);
      coun1 = new County("ft1", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("ft2",city1);
      city1.addCounty(coun1) ;
      pro.addCity(city1) ;
      provinces.addElement(pro);      // create the second province
      pro = new Province("He Bei");
      city1 = new City("shijazhuang", pro);
      coun1 = new County("sjz1", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("sjz2", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("sjz3",city1);
      city1.addCounty(coun1) ;
      pro.addCity(city1) ;
      city1 = new City("handan", pro);
      coun1 = new County("hd1", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("hd2",city1);
      city1.addCounty(coun1) ;
      coun1 = new County("hd3",city1);
      city1.addCounty(coun1) ;
      pro.addCity(city1) ;
      city1 = new City("bbb", pro);
      coun1 = new County("bbb1", city1);
      city1.addCounty(coun1) ;
      coun1 = new County("bbb2",city1);
      city1.addCounty(coun1) ;
      pro.addCity(city1) ;
      provinces.addElement(pro);      // set data of each comboBox
      comb1 = new JComboBox(provinces);
      comb2 = new JComboBox(((Province)provinces.elementAt(0) ).getCities() );
      comb3 = new JComboBox(((City)(((ComboBoxModel)comb2.getModel()).getSelectedItem())).getCounties() );
      comb1.addActionListener(new ActionListener(){
          public void actionPerformed(ActionEvent ae){
              System.out.println(comb1.getSelectedItem());
              System.out.println(((Province)comb1.getSelectedItem()).getCities() );
              DefaultComboBoxModel model = new DefaultComboBoxModel(((Province)comb1.getSelectedItem()).getCities() );
              comb2.setModel(model) ;
          }
      });      comb2.addActionListener(new ActionListener(){
          public void actionPerformed(ActionEvent ae){
            if(comb2.getSelectedItem() != null){
              System.out.println(comb2.getSelectedItem());
              System.out.println(((City)comb2.getSelectedItem()).getCounties()  );
              DefaultComboBoxModel model = new DefaultComboBoxModel(((City)comb2.getSelectedItem()).getCounties() );
              comb3.setModel(model) ;
            }
          }
      });
      this.getContentPane() .setLayout(new BorderLayout()) ;
      getContentPane() .add(comb1,BorderLayout.WEST);
      getContentPane() .add(comb2, BorderLayout.CENTER );
      getContentPane() .add(comb3,BorderLayout.EAST );
      setSize(400,80);
      setVisible(true) ;  }  public static void main(String args[]){
      Control3Combox c3c = new Control3Combox();  }
}class Province {
    private String name;
    private Vector cities;
    public Province(String name, Vector cities){
       this.name = name;
       this.cities= cities;
    }
    public Province (String name){
        this(name, new Vector());
    }
    public String toString(){
        return this.name;
    }
    public String getName(){return name;}    public void setName(String name){
      this.name= name;
    }    public Vector getCities(){return cities;}
    public void addCity (City oneCity){
        this.cities.addElement(oneCity);
    }
    public void setCities (Vector cities){
      this.cities = cities;
    }
}class City {
    private String name;
    private Province province;
    private Vector counties;
    public City(String name, Province p, Vector counties){
        this.name = name;
        this.province =p;
        this.counties = counties;
    }
    public City(String name, Province p){
      this(name,p, new Vector());
    }    public String toString(){
        return this.name;
    }    public String getName(){return name;}    public void setName(String name){
      this.name = name;
    }    public Vector getCounties(){return this.counties;}
    public void addCounty(County oneCounty){
        this.counties.addElement(oneCounty);
    }
    public void setCounties(Vector counties){
        this.counties=counties;
    }}class County{
    private City city;
    private String name;
    public County(String name, City city){
        this.name = name;
        this.city = city;
    }    public String toString(){
        return name;
    }    public String getName(){return this.name;}    public void setName(String name){
      this.name= name;
    }}