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(); } }