package solutions;
/*
* ListDataEventDemo.java requires the Java Look and Feel Graphics
* Repository (jlfgr-1_0.jar). You can download this file from
* http://java.sun.com/developer/techDocs/hi/repository/
* Put it in the class path using one of the following commands
* (assuming jlfgr-1_0.jar is in a subdirectory named jars):
*
* java -cp .;jars/jlfgr-1_0.jar ListDataEventDemo [Microsoft Windows]
* java -cp .:jars/jlfgr-1_0.jar ListDataEventDemo [UNIX]
*/
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class ListDataEventDemo extends JPanel
implements ListSelectionListener {
private JList list;
private DefaultListModel listModel;
private static final String addString = "Add";
private static final String deleteString = "Delete";
private static final String upString = "Move up";
private static final String downString = "Move down";
private JButton addButton;
private JButton deleteButton;
private JButton upButton;
private JButton downButton;
private JTextField nameField;
private JTextArea log;
static private String newline = "\n";
public ListDataEventDemo() {
super(new BorderLayout());
//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());
ImageIcon icon = createImageIcon("Up16");
if (icon != null) {
upButton = new JButton(icon);
upButton.setMargin(new Insets(0,0,0,0));
} else {
upButton = new JButton("Move up");
}
upButton.setToolTipText("Move the currently selected list item higher.");
upButton.setActionCommand(upString);
upButton.addActionListener(new UpDownListener());
icon = createImageIcon("Down16");
if (icon != null) {
downButton = new JButton(icon);
downButton.setMargin(new Insets(0,0,0,0));
} else {
downButton = new JButton("Move down");
}
downButton.setToolTipText("Move the currently selected list item lower.");
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, using 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);
splitPane.setResizeWeight(0.5);
//Put everything together.
add(buttonPane, BorderLayout.PAGE_START);
add(splitPane, BorderLayout.CENTER);
}
class MyListDataListener implements ListDataListener {
public void contentsChanged(ListDataEvent e) {
log.append("contentsChanged: " + e.getIndex0() +
", " + e.getIndex1() + newline);
log.setCaretPosition(log.getDocument().getLength());
}
public void intervalAdded(ListDataEvent e) {
log.append("intervalAdded: " + e.getIndex0() +
", " + e.getIndex1() + newline);
log.setCaretPosition(log.getDocument().getLength());
}
public void intervalRemoved(ListDataEvent e) {
log.append("intervalRemoved: " + e.getIndex0() +
", " + e.getIndex1() + newline);
log.setCaretPosition(log.getDocument().getLength());
}
}
class DeleteButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
/*
* This method can be called only if
* there's a valid selection,
* so go ahead and remove whatever's selected.
*/
ListSelectionModel lsm = list.getSelectionModel();
int firstSelected = lsm.getMinSelectionIndex();
int lastSelected = lsm.getMaxSelectionIndex();
listModel.removeRange(firstSelected, lastSelected);
int size = listModel.size();
if (size == 0) {
//List is empty: disable delete, up, and down buttons.
deleteButton.setEnabled(false);
upButton.setEnabled(false);
downButton.setEnabled(false);
} else {
//Adjust the selection.
if (firstSelected == listModel.getSize()) {
//Removed item in last position.
firstSelected--;
}
list.setSelectedIndex(firstSelected);
}
}
}
/** A listener shared by the text field and add button. */
class AddButtonListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
if (nameField.getText().equals("")) {
//User didn't type in a name...
Toolkit.getDefaultToolkit().beep();
return;
}
int index = list.getSelectedIndex();
int size = listModel.getSize();
//If no selection or if item in last position is selected,
//add the new one to end of list, and select new one.
if (index == -1 || (index+1 == size)) {
listModel.addElement(nameField.getText());
list.setSelectedIndex(size);
//Otherwise insert the new one after the current selection,
//and select new one.
} else {
listModel.insertElementAt(nameField.getText(), index+1);
list.setSelectedIndex(index+1);
}
}
}
//Listen for clicks on the up and down arrow buttons.
class UpDownListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//This method can be called only when
//there's a valid selection,
//so go ahead and move the list item.
int moveMe = list.getSelectedIndex();
if (e.getActionCommand().equals(upString)) {
//UP ARROW BUTTON
if (moveMe != 0) {
//not already at top
swap(moveMe, moveMe-1);
list.setSelectedIndex(moveMe-1);
list.ensureIndexIsVisible(moveMe-1);
}
} else {
//DOWN ARROW BUTTON
if (moveMe != listModel.getSize()-1) {
//not already at bottom
swap(moveMe, moveMe+1);
list.setSelectedIndex(moveMe+1);
list.ensureIndexIsVisible(moveMe+1);
}
}
}
}
//Swap two elements in the list.
private void swap(int a, int b) {
Object aObject = listModel.getElementAt(a);
Object bObject = listModel.getElementAt(b);
listModel.set(a, bObject);
listModel.set(b, aObject);
}
//Listener method for list selection changes.
public void valueChanged(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());
}
}
}
/** Returns an ImageIcon, or null if the path was invalid. */
protected static ImageIcon createImageIcon(String imageName) {
String imgLocation = "toolbarButtonGraphics/navigation/"
+ imageName
+ ".gif";
java.net.URL imageURL = ListDataEventDemo.class.getResource(imgLocation);
if (imageURL == null) {
System.err.println("Resource not found: "
+ imgLocation);
return null;
} else {
return new ImageIcon(imageURL);
}
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("ListDataEventDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
JComponent newContentPane = new ListDataEventDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Don't let the content pane get too small.
//(Works if the Java look and feel provides
//the window decorations.)
newContentPane.setMinimumSize(
new Dimension(
newContentPane.getPreferredSize().width,
100));
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}