java - 如何在java中的组合框之间使用过滤器？

Question

我的数据库中有两个表，分别是学期表和课程表。学期表中有学期 ID、课程 ID、课程名称和 Sdepartment（部门名称）。课程表有课程 ID 和课程名称。 我的 jframe 有两个组合框。第一个用于选择部门。第二个是选择课程。我想选择所选部门的课程。 选择部门时如何在组合框中调用课程名称？ 这是我的代码；

      public void coursename(){
     Session session = HibernateUtil.getSessionFactory().getCurrentSession();
     session.beginTransaction();
     //Query query= session.createQuery("select a.courseName,e.semesterId from Semester e inner join e.course as a"); 
     Query query= session.createQuery("FROM Senior.entity.Semester S  ");
     //for (Iterator it = query.iterate(); it.hasNext();) {
      //Object  row[] = (Object[])   it.next();
      //combocourse.addItem(new CourseItem((String)row[0], (int)row[1]));
      //}  
     List <Semester>re= query.list(); 
     if (re.size() > 0){ 
     Iterator iterate= re.iterator(); 
     final Semester resultAccount= (Semester)iterate.next(); 
     combocourse.removeAllItems();
     for(Semester inv:re){
     combocourse.addItem(new CourseItem(inv.getSemesterId(),inv.getSCourse()));
     }        
     }
      session.close();
   }


      public void depart(){
     Session session = HibernateUtil.getSessionFactory().getCurrentSession();
     session.beginTransaction();

     Query query= session.createQuery("FROM Senior.entity.Semester f "); 
     List <Semester>results= query.list(); 
     if (results.size() > 0){ 
     Iterator iterate= results.iterator(); 
     final Semester resultAccount= (Semester)iterate.next(); 
     combodepart.removeAllItems();
     for(Semester inv:results){
     combodepart.addItem(new DepartItem(inv.getSemesterId(),inv.getSDepartment()));

         //  combodepart.addActionListener(combocourse); 
               /*
            @Override
         public void actionPerformed(ActionEvent e) {
              JComboBox combocourse;
             combocourse = (JComboBox) e.getSource();
         //     Object selected = combocourse.getSelectedItem();
          Session session = HibernateUtil.getSessionFactory().getCurrentSession();
     session.beginTransaction();

     Query query= session.createQuery("FROM Senior.entity.Semester f "); 
     List <Semester>results= query.list(); 
     if (results.size() > 0){ 
     Iterator iterate= results.iterator(); 
     final Semester resultAccount= (Semester)iterate.next(); 
     combodepart.removeAllItems();
     for(Semester inv:results){
     combodepart.addItem(new DepartItem(inv.getSemesterId(),inv.getSDepartment()));
         }
     });

     */

     }        
     }
     session.close();
     }

Answer 1

一种方法是每次从部门组合框中选择一个项目时重置课程组合框的模型。

类似：

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

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 );

        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()
    {
        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();
            }
        });
    }
}

如何将此示例转换为数据库？

在 ActionListener 中查询数据库以获取所选部门的课程，然后创建模型。