java - JList DefaultListModel ListSelectionListener

Question

我在 JSplitPane 中有 2 个 DefaultListModel。 JSplitPane 的左侧有 RssChannel 标题。当选择 RssChannel 标题时，RssItem 标题应该显示在 JSplitPane 的右侧。

首次选择 RssChannel 标题时，会显示正确的 RssItem 标题。但是当我在 RssChannel 标题之间来回切换时，正确的 RssItem 标题不要开火。

如何修复我的监听器，以便始终从各自的 RssChannel 激发正确的 RssItem 标题？

感谢您的建议

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.util.List;
import java.util.ArrayList;
import java.io.*;


public class GuiDriver extends JFrame{
    JList channelTitleList, itemTitleList;
    DefaultListModel cModel, iModel;
    List<RssReader> feedList = new ArrayList<RssReader>();
    int nextFeed=0;

    public GuiDriver(){
    }

    public void addFeed(RssReader feed){
       feedList.add(feed);
    }


    public JToolBar createToolBar(){
       JToolBar bar = new JToolBar();
       Action newToolBarButton = new AddAction("New");
       Action deleteToolBarButton = new RemoveAction("Delete");
       Action clearToolBarButton = new ClearAction("Clear");

       bar.add(newToolBarButton);  
       bar.add(deleteToolBarButton);
       bar.add(clearToolBarButton);

       bar.setFloatable(false);      
       return bar;
    }


    public JSplitPane createJSplitPane(){
       JSplitPane hSplitPane  = new JSpli tPane(JSplitPane.HORIZONTAL_SPLIT,createChannelJScrollPane(), createItemJScrollPane());
       hSplitPane.setDividerLocation(500);
       return hSplitPane;
   }


   public JScrollPane createChannelJScrollPane(){            
      cModel = new DefaultListModel(); 
      channelTitleList = new JList(cModel);
      JScrollPane channelJScrollPane = new JScrollPane(channelTitleList);
      channelTitleList.setVisibleRowCount(20);
      channelTitleList.getSelectionModel.addListSelectionListener(new ChannelListListener());      

      return channelJScrollPane;     
   }


   public JScrollPane createItemJScrollPane(){
      iModel = new DefaultListModel();
      itemTitleList = new JList(iModel);
      JScrollPane itemJScrollPane = new JScrollPane(itemTitleList);

      return itemJScrollPane;
   }   


   public class AddAction extends AbstractAction{
      public AddAction(String name){
         super(name);
      }

      public void actionPerformed(ActionEvent e){
         System.out.println(getValue(Action.NAME)+" selected.");
         JOptionPane message = new JOptionPane();
         String firstInput = message.showInputDialog(null, "Enter URL");
         try{
            DumpStockPage.readXml(firstInput);
            File f = new File("RSSFeed.xml");
            addFeed(new RssReader(f));

            cModel.addElement(feedList.get(nextFeed).rssChannel.getTitle());
            nextFeed++;
            iModel.clear();
         }
         catch (IOException ee){
            System.err.println(ee);
         }
      }
   }


   public class RemoveAction extends AbstractAction{
      public RemoveAction(String name){
         super(name);
      }

      public void actionPerformed(ActionEvent e){
         cModel.removeElement(channelTitleList.getSelectedValue());
         feedList.remove(e);
         iModel.clear();
      } 
   }

   public class ClearAction extends AbstractAction{
      public ClearAction(String name){
         super(name);
      }

      public void actionPerformed(ActionEvent e){
         iModel.clear();
      } 
   }


   private class ChannelListListener implements ListSelectionListener {
      public void valueChanged (ListSelectionEvent e) {        
         boolean adjust = e.getValueIsAdjusting();
         if (!adjust) {
            int i = e.getLastIndex();
            for (int j=0; j<feedList.get(i).rssChannel.getItems().size(); j++)
               iModel.addElement(feedList.get(i).rssChannel.items.get(j).getTitle());
         }
      }
   }


   public static void main(String[] args) { 
      EventQueue.invokeLater(new Runnable() { 
         public void run() { 
            GuiDriver frame = new GuiDriver(); 

            frame.setTitle("RSS Reader");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
            frame.add(frame.createJSplitPane(), BorderLayout.NORTH);
            frame.add(frame.createToolBar(), BorderLayout.SOUTH);

            frame.setVisible(true);
            frame.setSize(800,400);
         }   
      });  
   }
}

Answer 1

我不确定 RssReader 的实现，但您的 ChannelListListener 不断向项目列表添加数据。您需要的是从 channelTitleList 中所选项目的标题列表。使用JList 的getSelectedIndex() 获取选定的索引。接下来，根据所选提要构建 itemTitleList 的内容，例如作为字符串列表。以下是 ChannelListListener 的示例，可帮助您入门:

public void valueChanged (ListSelectionEvent e) {        
     boolean adjust = e.getValueIsAdjusting();
     if (!adjust) {
        List<String> titles = new ArrayList<String>();
        int i = channelTitleList.getSelectedIndex(); //the index of the selected item in the left list

        //Change RssFeed to the appropriate class for these 'items'
        for(RssFeed feed: feedList.get(i).rssChannel.items) {
            titles.add(feed.getTitle());  //build a list of titles, to be shown in the right list
        }

        itemTitleList.setListData(titles.toArray()); //change the content of the right list
    }
}