A custom combobox editor for use with the EditableComboBox class

This Java Swing tip illustrates a method of creating a custom combobox editor for use with the EditableComboBox class. A combo box uses a renderer to display each item in its menu. An editable combo box, on the other hand, uses an editor to display the selected item.

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.border.*;

public 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);
}
}
}



source: http://java-tips.org