There are two ways to draw basic shapes like lines and rectangles.
The first is to use specific drawing methods like
Graphics.drawOval(). This example uses these methods. The
second is to construct a shape and then use Graphics2D.draw() to
draw the shape. See the java.awt.geom package for examples that
create shapes.
g2d.drawLine(x1, y1, x2, y2);
g2d.drawArc(x, y, w, h, startAngle, arcAngle);
g2d.drawOval(x, y, w, h);
g2d.drawRect(x, y, w, h);
g2d.drawRoundRect(x, y, w, h, arcWidth, arcHeight);
Polygon polygon = new Polygon();
polygon.addPoint(x, y);
// ...continue adding points
g2d.drawPolygon(polygon);