java Swing JComboBox下拉框显示图片问题

Question

public class mousergister extends JPanel {
JPanel jp;
JComboBox setImg;
ComboBoxRenderer renderer;

public static void main(String[] args) {
    new mousergister();
}

public mousergister() {
    BaseFrame bf=new BaseFrame("用户注册");
    bf.add(this);               
    this.setLayout(null);


    renderer = new ComboBoxRenderer();
    renderer.setPreferredSize(new Dimension(100, 50));

    Object elements[][] = {
            { new MyIcon("images/1.jpg",this)},
            { new MyIcon("images/2.gif",this) },
            { new MyIcon("images/3.jpg",this)},
            };

    setImg = new JComboBox(elements);
    setImg.setRenderer(renderer);           
    setImg.setBounds(120, 25, 75, 60);
    add(setImg);

    bf.setLocation(500, 100);// 设置窗口在屏幕的位置
    bf.setSize(320, 420);
    bf.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    bf.setResizable(false);// 设置游戏窗口大小不可改变
    bf.setVisible(true);

}

private class ComboBoxRenderer extends JLabel implements ListCellRenderer {

    // 这样要是实现接口的方法：

    /*
     * 
     * This method finds the image and text corresponding to the selected
     * 
     * value and returns the label, set up to display the text and image.
     */

    @Override
    public Component getListCellRendererComponent(JList list, Object value,
            int index, boolean isSelected, boolean cellHasFocus) {

        ImageIcon image=null;

         if (value instanceof Object[]) {
             Object[] values = (Object[]) value;                 
              image = (ImageIcon)values[0];
            }
            if (image != null) {

              this.setIcon(image);
            }
            return this;
          }          
}

private class MyIcon extends ImageIcon{
    private Image m;
    private String str;
    private mousergister jp;

    public MyIcon(String str,mousergister jp) {
        Toolkit tool;
        tool = jp.renderer.getToolkit();
        m = tool.getImage(str);
      }
     public void paintIcon(Component lab, Graphics g){
        lab=jp.renderer;

图片不会显示。。。怎么改？

Answer 1

getListCellRendererComponent()方法是需要修改的。参数value是Object类型，if的判断条件value instanceof Object[]不会成立，if代码块是不会执行的。if (value instanceof Object[]) {Object[] values = (Object[]) value;image = (ImageIcon)values[0];}if (image != null) {              this.setIcon(image);                }                return this;              }改成下面的试试。public Component getListCellRendererComponent(JList list, Object value,int index, boolean isSelected, boolean cellHasFocus) {        if (value != null) {             setIcon(new ImageIcon("images/1.jpg"));         }         if (isSelected) {             setBackground(list.getSelectionBackground());             setForeground(list.getSelectionForeground());         } else {             setBackground(list.getBackground());             setForeground(list.getForeground());         }         return this;     }

Answer 2

Object elements[][] = { { new MyIcon("images/1.jpg",this)}, { new MyIcon("images/2.gif",this) }, { new MyIcon("images/3.jpg",this)}, };这段直接用ImageIconObject elements[][] = { { new ImageIcon(this.getClass().getResource("images/1.jpg"))}, { new ImageIcon(this.getClass().getResource("images/2.gif")) }, { new ImageIcon(this.getClass().getResource("images/3.jpg"))}, };