初级学习资料必读本

				import java.awt.*;				import java.awt.event.*;				import javax.swing.*;								public class CustomComboBoxDemo extends JPanel {				    ImageIcon images[];								    public CustomComboBoxDemo() {				        //Load the pet images				        String[] petStrings = {"Bird", "Cat", "Dog", "Rabbit", "Pig"};				        images = new ImageIcon[petStrings.length];				        for (int i = 0; i < petStrings.length; i++) {				            images[i] = new ImageIcon("images/" + petStrings[i] + ".gif");				            images[i].setDescription(petStrings[i]);				        }								        // Create the combo box				        JComboBox petList = new JComboBox(images);				        ComboBoxRenderer renderer= new ComboBoxRenderer();				        renderer.setPreferredSize(new Dimension(200, 130));				        petList.setRenderer(renderer);				        petList.setMaximumRowCount(3);								        // Layout the demo				        setLayout(new BorderLayout());				        add(petList, BorderLayout.NORTH);				        setBorder(BorderFactory.createEmptyBorder(20,20,20,20));				    }								    public static void main(String s[]) {				        JFrame frame = new JFrame("CustomComboBoxDemo");				        frame.addWindowListener(new WindowAdapter() {				            public void windowClosing(WindowEvent e) {System.exit(0);}				        });				 				        frame.getContentPane().add(new CustomComboBoxDemo(),				                                   BorderLayout.CENTER);				        frame.pack();				        frame.setVisible(true);				    }								    class ComboBoxRenderer extends JLabel implements ListCellRenderer {				        public ComboBoxRenderer() {				            setOpaque(true);				            setHorizontalAlignment(CENTER);				            setVerticalAlignment(CENTER);				        }								        public Component getListCellRendererComponent(				                                           JList list,				                                           Object value,				                                           int index,				                                           boolean isSelected,				                                           boolean cellHasFocus) {				            if (isSelected) {				                setBackground(list.getSelectionBackground());				                setForeground(list.getSelectionForeground());				            } else {				                setBackground(list.getBackground());				                setForeground(list.getForeground());				            }								            ImageIcon icon = (ImageIcon)value;				            setText(icon.getDescription());				            setIcon(icon);				            return this;				        }				    }				}