需要與列表選擇監聽器的幫助

Question

我想用代碼填充我的列表選擇監聽器方法，但我不知道如何處理它。從本質上講，我希望當從JList中選擇一個項目時，該方法可以填充多個文本字段。

我JList的是這樣的：

private JList <String> contactList; 
private DefaultListModel<String> model; 

//Textfields 
comboBookType = new JComboBox(BookType.values()); 
nameText = new JTextField("", 17); 
authorText = new JTextField("", 17); 
genreText = new JTextField ("", 17); 
comboCategory = new JComboBox (readCategory()); 

//initialize defaultlistmodel and jlist 
model = new DefaultListModel <String>(); 
bookList = new JList (model); 
bookList.setVisibleRowCount(10); 
bookList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); 
bookList.setFixedCellHeight (20); 
bookList.setFixedCellWidth (130); 
bookList.setBorder (BorderFactory.createLineBorder(Color.BLACK,1)); 
JPanel left = new JPanel(new BorderLayout()); 
left.add (new JScrollPane(bookList), BorderLayout.NORTH); 
bookList.addListSelectionListener (new ListSelection()); 

//populating Jlist 
class openFileListener implements ActionListener 
{ 

    public void actionPerformed(ActionEvent e) 
    { 

     book.getBooks(); 
     for (String name : addressBook.getBooks()) 
     { 
     model.addElement(name); 
     } 
    } 
} 

//the getBooks() method in my Library class 
public ArrayList<String> getBooks() 
{ 
    File file; 
    Scanner input; 
    BookType type; 
    ArrayList<String> books; 
    ArrayList<String> names = new ArrayList<String>(); 
    try 
    { 
    file = new File ("Books.txt"); 
    input = new Scanner (file);  

    while (input.hasNext()) 
    { 

     String line = input.nextLine (); 
     String [] book = line.split(","); 
     type = BookType.valueOf(info[0]); 
     String name = book[1]; 
     b = new Book (type, book[1], book[2], book[3], book[4], info[5]); 
     list.add (b); 
     information.add (name); 

     numOfBooks++; 
    } 
    input.close (); 
    } 
    catch (FileNotFoundException e) 
    { 
    JOptionPane.showMessageDialog (null, "File not found"); 
    } 
    return information; 
} 

這裏是我到目前爲止我的列表中選擇偵聽器：

private class ListSelection implements ListSelectionListener 
{ 
    public void valueChanged (ListSelectionEvent e) 
    { 
    book.getInfo (); 
    int index = bookList.getSelectedIndex (); 
} 


//getInfo() method in Library class 

public ArrayList<Book> getInfo() 
{ 
    File file; 
    Scanner input; 
    BookType type; 
    ArrayList<String> book; 
    try 
    { 
    file = new File ("Book.txt"); 
    input = new Scanner (file);  

    while (input.hasNext()) 
    { 
     String line = input.nextLine (); 
     String [] info = line.split(","); 
     type = BookType.valueOf(info[0]); 
     String name = info[1]; 
     Book b = new Contact (type, info[1], info[2], info[3], info[4],info[5]); 
     list.add (b); 
    } 
    input.close (); 
    } 
    catch (FileNotFoundException e) 
    { 
    JOptionPane.showMessageDialog (null, "File not found"); 
    } 
    return list; 

這不是很多，但我有從哪裏去沒轍這裏。我知道我必須利用從getSelectedIndex得到的index，但我不知道如何，請幫助，謝謝。

Answer 1

我知道我必須利用了我從getSelectedIndex得到了指數，但我不知道該怎麼

你會使用索引來從ListModel選擇項：

String book = model.getElementAt(index); 

或者更簡單的方法是使用getSelectedValue()方法來從JList元素：

private class ListSelection implements ListSelectionListener 
{ 
    public void valueChanged (ListSelectionEvent e) 
    { 
     if (e.getValueIsAdjusting()) return; 

     //book.getInfo (); 
     //int index = bookList.getSelectedIndex (); 
     String book = bookList.getSelectedValue(); 
    } 
} 

現在你遇到的問題是找到關於該書的信息。您正在創建Book對象並將它們添加到ArrayList。所以現在你需要創建一個循環來查看ArrayList中的所有條目。例如：

ArrayList<Book> bookInfo = getInfo(); 

for (Book book: bookInfo) 
{ 
    if (book.equals(book.getTitle()) 
    { 
     authorTextField.setText(book.getAuthor()); 
     // ... for the rest of the text fields 
     return; 
    } 
} 

請注意，更好的設計是在課程構建完成後將書籍信息讀入您的課程。每次在JList中進行選擇時，都不要從文本文件中讀取數據。