JTable DefaultCellRenderer doesn't work on BigDecimal Type when I set Object.class

It is weird that I set my JTable cell renderer like this:

setDefaultRenderer(Object.class, new MyTableRenderer());

My table renderer works like this:

class MyTableRenderer extends DefaultTableCellRenderer {
    public Component getTableCellRendererComponent(JTable table, Object value,
                    boolean isSelected, boolean hasFocus, int row, int column) {
        Component comp = super.getTableCellRendererComponent(table, value,
                                            isSelected, hasFocus, row, column);
        Font font = comp.getFont();

        if (table.getModel().getValueAt(row, 0).equals(BUY)) {
            comp.setFont(font.deriveFont(Font.BOLD));
            comp.setForeground(BUY_COLOR);
        }
        else {
            comp.setFont(font.deriveFont(Font.BOLD开发者_运维技巧));
            comp.setForeground(SELL_COLOR);
        }
        return comp;
    }
}

But it turns out, it didin't apply those columns that have type "BigDecimal", Other String fields are all working fine.

And then, I add one more line:

setDefaultRenderer(BigDecimal.class, new MyTableRenderer());

Then everything just work fine. Why it is like this?

JTable by default installs a renderer for type Number. BigDecimal is-a Number so the default renderer is used instead of your custom renderer.

BTW: your custom renderer is buggy in that it doesn't take potentially sorted/filtered rows into account (the row/column index params of the method are view coordinates).

@eugener: your answer is wrong - it's not the storage that's important but the lookup ;-)

Cheers Jeanette

Take look at the source code of the JTable:

public void setDefaultRenderer(Class<?> columnClass, TableCellRenderer renderer) {
  if (renderer != null) {
      defaultRenderersByColumnClass.put(columnClass, renderer);
  } else {
      defaultRenderersByColumnClass.remove(columnClass);
  } 
}

It uses a map where column class is a key and means that class comparison is literal. This should explain the reason for behavior you're experiencing. This is by design.