JTable: How do you get the sort indicator shown in the design guidelines ?

Question

http://java.sun.com/products/jlf/at/book/Idioms4.html#996747
As opposed to Volume 1, they don't provide any code :-(
(http://java.sun.com/products/jlf/)

Answer 1

You need to put your own TableCellRenderer into the table header. You implement the same interface as an ordinary cell renderer, but you install it differently. Here's a snippet of my code that does this:
     private void setupHeaderRenderers()
          for (int i = 0; i < model_.getColumnCount(); i++)
               TableColumn tc = t_.getColumnModel().getColumn(i);
               tc.setHeaderRenderer(new SortHeaderRenderer(/* my ctor args */));
     }and the renderer itself is as below. Apologies for dependencies on other stuff of mine, but you get the idea.
private class SortHeaderRenderer extends    DefaultTableCellRenderer
  RenderInfo r_;
  SortHeaderRenderer(RenderInfo r)
    r_ = r;
  public Component getTableCellRendererComponent(javax.swing.JTable table,
                                                Object  value,
                                boolean isSelected,
                                                boolean hasFocus,
                                                int     row,
                                                int     column)
      if (table != null)
        JTableHeader header = table.getTableHeader();
        if (header != null)
          setForeground(header.getForeground());
          setBackground(header.getBackground());
          setFont(header.getFont());
      setText((value == null) ? "" : value.toString());
      setBorder(UIManager.getBorder("TableHeader.cellBorder"));
      setHorizontalAlignment(SwingConstants.CENTER);
      setHorizontalTextPosition(SwingConstants.LEFT);
      // Check if we are the primary sort column and if so, which
      // direction the sort is in
      if ((orderItems_ != null) && (orderItems_.contains(r_)))
        if (sortDescending_)
          setIcon(sortDescending__.getIcon());
        else
          setIcon(sortAscending__.getIcon());
      else
        setIcon(null);
      return this;