Thread: Please help resolve warning re parameterized types / Jlist ListCellRenderer

I'm developing a desktop app using JDK 1.7.0 on a Windows 7 machine, not that that should matter. My question is about parameterized types and specifically a ListCellRenderer for a JList. I have included both an example of the the warnings I am receiving and the code that the compiler is complaining about.

I admit that I'm still very new to Swing and not all that comfortable with parameterized types beyond simple cases. Any words of wisedom regarding these warnings will be appreciated as will recommendations for a good tutorial on parameterized types.

 

warning: [unchecked] unchecked call to setCellRenderer(ListCellRenderer<? super E>) as a member of the raw type JList

        scrollingList.setCellRenderer(new MyListCellRenderer());

  where E is a type-variable:

    E extends Object declared in class JList

class MyListCellRenderer extends JLabel 
                         implements ListCellRenderer<Object> {
 
    public MyListCellRenderer() {
        setOpaque(true);
    }
 
    @Override
    public Component getListCellRendererComponent(JList<?> list,
                                                  Object value,
                                                  int index,
                                                  boolean isSelected,
                                                  boolean cellHasFocus) {
 
        setText(((JLabel)value).getText());
        setIcon(((JLabel)value).getIcon());
 
        Color background;
        Color foreground;
 
        // check if this cell represents the current DnD drop location
        JList.DropLocation dropLocation = list.getDropLocation();
        if (dropLocation != null
        && !dropLocation.isInsert()
        && dropLocation.getIndex() == index) {
            background = Color.PINK.darker();
            foreground = Color.CYAN.brighter();
        }
        else if (isSelected) {
            background = list.getSelectionBackground();
            foreground = list.getSelectionForeground();
        }
        else {
            background = Color.WHITE;  // getBackground is ugly
            foreground = list.getForeground();
        }
 
        setBackground(background);
        setForeground(foreground);
 
        return this;
    }
}