More Conditionals and Loops - Java Software Solutions: Foundations of Program Design - page 287

LISTING 6.6
//********************************************************************
// BullseyePanel.java Author: Lewis/Loftus
//
// Demonstrates the use of conditionals and loops to guide drawing.
//********************************************************************
import javax.swing.JPanel;
import java.awt.*;
public class BullseyePanel extends JPanel
{
private final int MAX_WIDTH = 300, NUM_RINGS = 5, RING_WIDTH = 25;
//-----------------------------------------------------------------
// Sets up the bullseye panel.
//-----------------------------------------------------------------
public BullseyePanel ()
{
setBackground (Color.cyan);
setPreferredSize ( new Dimension(300,300));
}
//-----------------------------------------------------------------
// Paints a bullseye target.
//-----------------------------------------------------------------
public void paintComponent (Graphics page)
{
super .paintComponent (page);
int x = 0, y = 0, diameter = MAX_WIDTH;
page.setColor (Color.white);
for ( int count = 0; count < NUM_RINGS; count++)
{
if (page.getColor() == Color.black) // alternate colors
page.setColor (Color.white);
else
page.setColor (Color.black);
page.fillOval (x, y, diameter, diameter);