Getting incorrect JComboBox color through UIManager in Nimbus Look&Feel

Question

Hello all,
As I implementing a multi columns JComboBox, I need to provide my own custom ListCellRenderer.
* @author yccheok
public class ResultSetCellRenderer extends javax.swing.JPanel implements ListCellRenderer {
    // Do not use static, so that our on-the-fly look n feel change will work.
    private final Color cfc  = UIManager.getColor("ComboBox.foreground");
    private final Color cbc  = UIManager.getColor("ComboBox.background");
    private final Color csfc = UIManager.getColor("ComboBox.selectionForeground");
    private final Color csbc = UIManager.getColor("ComboBox.selectionBackground");
    private final Color cdfc = UIManager.getColor("ComboBox.disabledForeground");
    @Override
    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
        System.out.println("UIManager.getColor(ComboBox.selectionForeground) = " + UIManager.getColor("ComboBox.selectionForeground"));
        System.out.println("UIManager.getColor(ComboBox.selectionBackground) = " + UIManager.getColor("ComboBox.selectionBackground"));
        this.setBackground(isSelected ? csbc : cbc);
     this.setForeground(isSelected ? csfc : cfc);
        jLabel1.setBackground(isSelected ? csbc : cbc);
     jLabel1.setForeground(isSelected ? csfc : cfc);
        jLabel2.setBackground(isSelected ? csbc : cbc);
     jLabel2.setForeground(isSelected ? csfc : cfc);
        jLabel3.setBackground(isSelected ? csbc : cbc);
     jLabel3.setForeground(cdfc);
        final ResultType result = (ResultType)value;
        jLabel1.setText(result.symbol);
        jLabel2.setText(result.name);
        final String type = result.typeDisp != null ? result.typeDisp : result.type;
        final String exch = result.exchDisp != null ? result.exchDisp : result.exch;
        jLabel3.setText(type  + " - " + exch);
        return this;
}I try to get the selection colors of JComboBox through UIManager.
    private final Color csfc = UIManager.getColor("ComboBox.selectionForeground");
    private final Color csbc = UIManager.getColor("ComboBox.selectionBackground");However, I realize that while I am in Nimbus Look & Feel, the above 2 return me null.
May I know is there any workaround to overcome this? Or I had missed out something?
Thanks.
Edited by: yccheok on Oct 21, 2010 10:39 AM

Answer 1

because "c" is instance of UIResource:
import java.awt.*;
import javax.swing.*;
import javax.swing.plaf.*;
public class NimbusComponentColorTest {
  public JComponent makeUI() {
    final Color c = UIManager.getColor(
        "ComboBox:\"ComboBox.renderer\"[Selected].background");
    System.out.format("c instanceof UIResource: %s", c instanceof UIResource);
    JLabel label01 = new JLabel("label01");
    /* //com/sun/java/swing/plaf/nimbus/AbstractRegionPainter.java
    protected final Color getComponentColor(...) {
      // we return the defaultColor if the color found is null, or if
      // it is a UIResource. This is done because the color for the
      // ENABLED state is set on the component, but you don't want to use
      // that color for the over state. So we only respect the color
      // specified for the property if it was set by the user, as opposed
      // to set by us.
      if (color == null || color instanceof UIResource) {
          return defaultColor;
      } else if(saturationOffset!=0||brightnessOffset!=0||alphaOffset!=0) {
    label01.setOpaque(true);
    label01.setBackground(c);
    JLabel label02 = new JLabel("label02");
    label02.setOpaque(true);
    label02.setUI(new javax.swing.plaf.metal.MetalLabelUI());
    label02.setBackground(c);
    JLabel label03 = new JLabel("label03") {
      @Override public void paintComponent(Graphics g) {
        g.setColor(c);
        g.fillRect(0,0,getWidth(),getHeight());
        super.paintComponent(g);
    JLabel label04 = new JLabel("label04");
    label04.setOpaque(true);
    label04.setBackground(new ColorUIResource(Color.RED));
    JPanel p = new JPanel();
    p.add(label01); p.add(label02); p.add(label03); p.add(label04);
    return p;
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() { createAndShowGUI(); }
  public static void createAndShowGUI() {
    try {
      for (UIManager.LookAndFeelInfo laf:UIManager.getInstalledLookAndFeels())
        if ("Nimbus".equals(laf.getName()))
          UIManager.setLookAndFeel(laf.getClassName());
    } catch (Exception e) {
      e.printStackTrace();
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.getContentPane().add(new NimbusComponentColorTest().makeUI());
    f.setSize(200, 100);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
}