Java Tips - 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);

        }

    }

}
Related Tips
