public class TestJList extends JFrame {

    public TestJList() {

        JList list = new JList(new String[] { "cc", "zz", "pp" });

        this.add(list);

        list.setCellRenderer(new DefaultListCellRenderer() {

            public void paintComponent(Graphics g) {

                super.paintComponent(g);

                g.setColor(Color.red);

                g.drawLine(0, getHeight() - 1, getWidth(), getHeight() - 1);

            }

        });

        this.setTitle("Test JList");

        this.pack();

        this.setVisible(true);

    }

    public static void main(String[] args) {

        TestJList t = new TestJList();

    }

}