code: protected Icon getHeaderRendererIcon(boolean bCurrentOrder) {
          // Get current classloader
          ClassLoader cl = this.getClass().getClassLoader();
          // Create icons
          try   {
              if (ASCENDING_ICON == null)
              {
                  ASCENDING_ICON  = new ImageIcon(cl.getResource("images/buttons/" + ASCENDING_ICON_NAME + ".gif"));
                  DESCENDING_ICON  = new ImageIcon(cl.getResource("images/buttons/" + DESCENDING_ICON_NAME + ".gif"));
              }
              return bCurrentOrder ? ASCENDING_ICON : DESCENDING_ICON;
          } catch (Exception ex)  {
          }
          return null;
      }
docs: Get the ascending/descending icon.