A fancy example of JComboBox with a custom renderer and editor
/*
Java Swing, 2nd Edition
By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole
ISBN: 0-596-00408-7
Publisher: O'Reilly
*/
// EditableComboBox.java
//A fancy example of JComboBox with a custom renderer and editor used to
//display a list of JLabel objects that include both text and icons.
//
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.ComboBoxEditor;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.BevelBorder;
public class EditableComboBox extends JPanel {
private BookEntry books[] = {
new BookEntry("Ant: The Definitive Guide", "covers/ant.gif"),
new BookEntry("Database Programming with JDBC and Java",
"covers/jdbc.gif"),
new BookEntry("Developing Java Beans", "covers/beans.gif"),
new BookEntry("Developing JSP Custom Tag Libraries",
"covers/jsptl.gif"),
new BookEntry("Java 2D Graphics", "covers/java2d.gif"),
new BookEntry("Java and XML", "covers/jxml.gif"),
new BookEntry("Java and XSLT", "covers/jxslt.gif"),
new BookEntry("Java and SOAP", "covers/jsoap.gif"),
new BookEntry("Java and XML Data Binding", "covers/jxmldb.gif"),
new BookEntry("Java Cookbook", "covers/jcook.gif"),
new BookEntry("Java Cryptography", "covers/jcrypto.gif"),
new BookEntry("Java Distributed Computing", "covers/jdist.gif"),
new BookEntry("Java I/O", "covers/javaio.gif"),
new BookEntry("Java in a Nutshell", "covers/javanut.gif"),
new BookEntry("Java Management Extensions", "covers/jmx.gif"),
new BookEntry("Java Message Service", "covers/jms.gif"),
new BookEntry("Java Network Programming", "covers/jnetp.gif"),
new BookEntry("Java Performance Tuning", "covers/jperf.gif"),
new BookEntry("Java RMI", "covers/jrmi.gif"),
new BookEntry("Java Security", "covers/jsec.gif"),
new BookEntry("JavaServer Pages", "covers/jsp.gif"),
new BookEntry("Java Servlet Programming", "covers/servlet.gif"),
new BookEntry("Java Swing", "covers/swing.gif"),
new BookEntry("Java Threads", "covers/jthread.gif"),
new BookEntry("Java Web Services", "covers/jws.gif"),
new BookEntry("Learning Java", "covers/learnj.gif") };
Map bookMap = new HashMap();
public EditableComboBox() {
// Build a mapping from book titles to their entries
for (int i = 0; i < books.length; i++) {
bookMap.put(books[i].getTitle(), books[i]);
}
setLayout(new BorderLayout());
JComboBox bookCombo = new JComboBox(books);
bookCombo.setEditable(true);
bookCombo.setEditor(new ComboBoxEditorExample(bookMap, books[0]));
bookCombo.setMaximumRowCount(4);
bookCombo.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("You chose "
+ ((JComboBox) e.getSource()).getSelectedItem() + "!");
}
});
bookCombo.setActionCommand("Hello");
add(bookCombo, BorderLayout.CENTER);
}
public static void main(String s[]) {
JFrame frame = new JFrame("Combo Box Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new EditableComboBox());
frame.pack();
frame.setVisible(true);
}
}
class BookEntry {
private final String title;
private final String imagePath;
private ImageIcon image;
public BookEntry(String title, String imagePath) {
this.title = title;
this.imagePath = imagePath;
}
public String getTitle() {
return title;
}
public ImageIcon getImage() {
if (image == null) {
image = new ImageIcon(imagePath);
}
return image;
}
// Override standard toString method to give a useful result
public String toString() {
return title;
}
}
class ComboBoxEditorExample implements ComboBoxEditor {
Map map;
ImagePanel panel;
ImageIcon questionIcon;
public ComboBoxEditorExample(Map m, BookEntry defaultChoice) {
map = m;
panel = new ImagePanel(defaultChoice);
questionIcon = new ImageIcon("question.gif");
}
public void setItem(Object anObject) {
if (anObject != null) {
panel.setText(anObject.toString());
BookEntry entry = (BookEntry) map.get(anObject.toString());
if (entry != null)
panel.setIcon(entry.getImage());
else
panel.setIcon(questionIcon);
}
}
public Component getEditorComponent() {
return panel;
}
public Object getItem() {
return panel.getText();
}
public void selectAll() {
panel.selectAll();
}
public void addActionListener(ActionListener l) {
panel.addActionListener(l);
}
public void removeActionListener(ActionListener l) {
panel.removeActionListener(l);
}
// We create our own inner class to handle setting and
// repainting the image and the text.
class ImagePanel extends JPanel {
JLabel imageIconLabel;
JTextField textField;
public ImagePanel(BookEntry initialEntry) {
setLayout(new BorderLayout());
imageIconLabel = new JLabel(initialEntry.getImage());
imageIconLabel.setBorder(new BevelBorder(BevelBorder.RAISED));
textField = new JTextField(initialEntry.getTitle());
textField.setColumns(45);
textField.setBorder(new BevelBorder(BevelBorder.LOWERED));
add(imageIconLabel, BorderLayout.WEST);
add(textField, BorderLayout.EAST);
}
public void setText(String s) {
textField.setText(s);
}
public String getText() {
return (textField.getText());
}
public void setIcon(Icon i) {
imageIconLabel.setIcon(i);
repaint();
}
public void selectAll() {
textField.selectAll();
}
public void addActionListener(ActionListener l) {
textField.addActionListener(l);
}
public void removeActionListener(ActionListener l) {
textField.removeActionListener(l);
}
}
}
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