FileDocCategorySizeDatePackage
ListDataEventDemo.javaAPI DocExample9366Tue Dec 12 18:58:54 GMT 2000None

ListDataEventDemo

public class ListDataEventDemo extends JApplet implements ListSelectionListener

Fields Summary
private JList
list
private DefaultListModel
listModel
private static final String
addString
private static final String
deleteString
private static final String
upString
private static final String
downString
private JButton
addButton
private JButton
deleteButton
private JButton
upButton
private JButton
downButton
private JTextField
nameField
private JTextArea
log
private static String
newline
Constructors Summary
Methods Summary
protected java.net.URLgetURL(java.lang.String filename)

        URL codeBase = this.getCodeBase();
        URL url = null;

        try {
            url = new URL(codeBase, filename);
        } catch (java.net.MalformedURLException e) {
            System.out.println("Couldn't create image: badly specified URL");
            return null;
        }

        return url;
public voidinit()


       
        //Create and populate the list model.
        listModel = new DefaultListModel();
        listModel.addElement("Whistler, Canada");
        listModel.addElement("Jackson Hole, Wyoming");
        listModel.addElement("Squaw Valley, California");
        listModel.addElement("Telluride, Colorado");
        listModel.addElement("Taos, New Mexico");
        listModel.addElement("Snowbird, Utah");
        listModel.addElement("Chamonix, France");
        listModel.addElement("Banff, Canada");
        listModel.addElement("Arapahoe Basin, Colorado");
        listModel.addElement("Kirkwood, California");
        listModel.addElement("Sun Valley, Idaho");
        listModel.addListDataListener(new MyListDataListener());

        //Create the list and put it in a scroll pane.
        list = new JList(listModel);
        list.setSelectionMode(
            ListSelectionModel.SINGLE_INTERVAL_SELECTION);
        list.setSelectedIndex(0);
        list.addListSelectionListener(this);
        JScrollPane listScrollPane = new JScrollPane(list);

        //Create the list modifying buttons.
        addButton = new JButton(addString);
        addButton.setActionCommand(addString);
        addButton.addActionListener(new AddButtonListener());

        deleteButton = new JButton(deleteString);
        deleteButton.setActionCommand(deleteString);
        deleteButton.addActionListener(
            new DeleteButtonListener());

        upButton = new JButton(
            new ImageIcon(getURL("images/up.gif")));
        upButton.setMargin(new Insets(0,0,0,0));
        upButton.setActionCommand(upString);
        upButton.addActionListener(new UpDownListener());

        downButton = new JButton(
            new ImageIcon(getURL("images/down.gif")));
        downButton.setMargin(new Insets(0,0,0,0));
        downButton.setActionCommand(downString);
        downButton.addActionListener(new UpDownListener());

        JPanel upDownPanel = new JPanel(new GridLayout(2, 1));
        upDownPanel.add(upButton);
        upDownPanel.add(downButton);

        //Create the text field for entering new names.
        nameField = new JTextField(15);
        nameField.addActionListener(new AddButtonListener());
        String name = listModel.getElementAt(list.getSelectedIndex())
                               .toString();
        nameField.setText(name);

        //Create a control panel (uses the default FlowLayout).
        JPanel buttonPane = new JPanel();
        buttonPane.add(nameField);
        buttonPane.add(addButton);
        buttonPane.add(deleteButton);
        buttonPane.add(upDownPanel);

        //Create the log for reporting list data events.
        log = new JTextArea(10, 20);
        JScrollPane logScrollPane = new JScrollPane(log);

        //Create a split pane for the log and the list.
        JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                                        listScrollPane, logScrollPane);

        Container contentPane = getContentPane();
        contentPane.add(buttonPane, BorderLayout.NORTH);
        contentPane.add(splitPane, BorderLayout.CENTER);
private voidswap(int a, int b)

        Object aObject = listModel.getElementAt(a);
        Object bObject = listModel.getElementAt(b);
        listModel.set(a, bObject);
        listModel.set(b, aObject);
public voidvalueChanged(javax.swing.event.ListSelectionEvent e)

        if (e.getValueIsAdjusting() == false) {

            if (list.getSelectedIndex() == -1) {
            //No selection: disable delete, up, and down buttons.
                deleteButton.setEnabled(false);
                upButton.setEnabled(false);
                downButton.setEnabled(false);
                nameField.setText("");

            } else if (list.getSelectedIndices().length > 1) {
            //Multiple selection: disable up and down buttons.
                deleteButton.setEnabled(true);
                upButton.setEnabled(false);
                downButton.setEnabled(false);

            } else {
            //Single selection: permit all operations.
                deleteButton.setEnabled(true);
                upButton.setEnabled(true);
                downButton.setEnabled(true);
                nameField.setText(list.getSelectedValue().toString());
            }
        }