customize jcomboboc

                                    package net.codejava.swing.combobox;
 
import java.awt.Dimension;
import java.awt.FlowLayout;
 
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
 
public class CustomComboBoxTester extends JFrame {
     
    public CustomComboBoxTester() {
        super("Demo program for custom combobox");
        setLayout(new FlowLayout());
         
        CountryComboBox customCombobox = new CountryComboBox();
        customCombobox.setPreferredSize(new Dimension(120, 30));
        customCombobox.setEditable(true);
        customCombobox.addItems(countryList);
         
        add(customCombobox);
 
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(400, 100);
        setLocationRelativeTo(null);    // center on screen
    }
     
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new CustomComboBoxTester().setVisible(true);
            }
        });
    }
 
    private String[][] countryList = {{"USA", "us.png"},
                                      {"India", "in.png"},
                                      {"Vietnam", "vn.png"},
                                      {"Germany", "de.png"},
                                      {"Canada", "ca.png"},
                                      {"Japan", "jp.png"},
                                      {"Great Britain", "gb.png"},
                                      {"France", "fr.png"}};
}

                                    package net.codejava.swing.combobox;
 
import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
 
/**
 * A custom combo box with its own renderer and editor.
 * @author wwww.codejava.net
 *
 */
public class CountryComboBox extends JComboBox {
    private DefaultComboBoxModel model;
     
    public CountryComboBox() {
        model = new DefaultComboBoxModel();
        setModel(model);
        setRenderer(new CountryItemRenderer());
        setEditor(new CountryItemEditor());
    }
     
    /**
     * Add an array items to this combo box.
     * Each item is an array of two String elements:
     * - first element is country name.
     * - second element is path of an image file for country flag.
     * @param items
     */
    public void addItems(String[][] items) {
        for (String[] anItem : items) {
            model.addElement(anItem);
        }
    }
}

                                    package net.codejava.swing.combobox;
 
import java.awt.Color;
import java.awt.Component;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
 
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.plaf.basic.BasicComboBoxEditor;
 
/**
 * Editor for JComboBox
 * @author wwww.codejava.net
 *
 */
public class CountryItemEditor extends BasicComboBoxEditor {
    private JPanel panel = new JPanel();
    private JLabel labelItem = new JLabel();
    private String selectedValue;
     
    public CountryItemEditor() {
        panel.setLayout(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.fill = GridBagConstraints.HORIZONTAL;
        constraints.weightx = 1.0;
        constraints.insets = new Insets(2, 5, 2, 2);
         
        labelItem.setOpaque(false);
        labelItem.setHorizontalAlignment(JLabel.LEFT);
        labelItem.setForeground(Color.WHITE);
         
        panel.add(labelItem, constraints);
        panel.setBackground(Color.BLUE);        
    }
     
    public Component getEditorComponent() {
        return this.panel;
    }
     
    public Object getItem() {
        return this.selectedValue;
    }
     
    public void setItem(Object item) {
        if (item == null) {
            return;
        }
        String[] countryItem = (String[]) item;
        selectedValue = countryItem[0];
        labelItem.setText(selectedValue);
        labelItem.setIcon(new ImageIcon(countryItem[1]));       
    }   
}

                                    package net.codejava.swing.combobox;
 
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.Font;
 
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.plaf.basic.BasicComboBoxEditor;
 
public class MyComboBoxEditor extends BasicComboBoxEditor {
    private JLabel label = new JLabel();
    private JPanel panel = new JPanel();
    private Object selectedItem;
     
    public MyComboBoxEditor() {
         
        label.setOpaque(false);
        label.setFont(new Font("Arial", Font.BOLD, 14));
        label.setForeground(Color.BLACK);
         
        panel.setLayout(new FlowLayout(FlowLayout.LEFT, 5, 2));
        panel.add(label);
        panel.setBackground(Color.GREEN);
    }
     
    public Component getEditorComponent() {
        return this.panel;
    }
     
    public Object getItem() {
        return "[" + this.selectedItem.toString() + "]";
    }
     
    public void setItem(Object item) {
        this.selectedItem = item;
        label.setText(item.toString());
    }
     
}

                                    package net.codejava.swing.combobox;
 
import java.awt.Color;
import java.awt.Component;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
 
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.ListCellRenderer;
 
/**
 * Customer renderer for JComboBox
 * @author www.codejava.net
 *
 */
public class CountryItemRenderer extends JPanel implements ListCellRenderer {
    private JLabel labelItem = new JLabel();
     
    public CountryItemRenderer() {
        setLayout(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.fill = GridBagConstraints.HORIZONTAL;
        constraints.weightx = 1.0;
        constraints.insets = new Insets(2, 2, 2, 2);
         
        labelItem.setOpaque(true);
        labelItem.setHorizontalAlignment(JLabel.LEFT);
         
        add(labelItem, constraints);
        setBackground(Color.LIGHT_GRAY);
    }
     
    @Override
    public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus) {
        String[] countryItem = (String[]) value;
 
        // set country name
        labelItem.setText(countryItem[0]);
         
        // set country flag
        labelItem.setIcon(new ImageIcon(countryItem[1]));
         
        if (isSelected) {
            labelItem.setBackground(Color.BLUE);
            labelItem.setForeground(Color.YELLOW);
        } else {
            labelItem.setForeground(Color.BLACK);
            labelItem.setBackground(Color.LIGHT_GRAY);
        }
         
        return this;
    }
 
}