Arrays - Java Software Solutions: Foundations of Program Design - page 421

LISTING 8.18 continued

private ArrayList<Point> pointList;

//-----------------------------------------------------------------
// Constructor: Sets up this panel to listen for mouse events.
//-----------------------------------------------------------------
public DotsPanel()
{
pointList = new ArrayList<Point>();

addMouseListener ( new DotsListener());

setBackground (Color.black);
setPreferredSize ( new Dimension(300, 200));
}

//-----------------------------------------------------------------
// Draws all of the dots stored in the list.
//-----------------------------------------------------------------
public void paintComponent (Graphics page)
{
super .paintComponent(page);

page.setColor (Color.green);

for (Point spot : pointList)
page.fillOval (spot.x-SIZE, spot.y-SIZE, SIZE*2, SIZE*2);

page.drawString ("Count: " + pointList.size(), 5, 15);
}

//*****************************************************************
// Represents the listener for mouse events.
//*****************************************************************
private class DotsListener implements MouseListener
{
//--------------------------------------------------------------
// Adds the current point to the list of points and redraws
// the panel whenever the mouse button is pressed.
//--------------------------------------------------------------
public void mousePressed (MouseEvent event)
{
pointList.add(event.getPoint());
repaint();
}