Learning Java

Stroking Shape Outlines

Just as a Graphics2D object’s current paint determines how its shapes are filled, its current stoke determines how its shapes are outlined. The current stroke includes information about line thickness, line dashing, and end styles. (If you struggled with drawing in earlier versions of Java, you’ll be very grateful that there’s now a way to change the line thickness.)

To set the current stroke in a Graphics2D, just call setStroke( ) with any implementation of the Stroke interface. Fortunately, the 2D API includes a BasicStroke class that probably does everything you need. Using BasicStroke, you can create dashed lines, control what decoration is added to line ends, and decide how the corners in an outline should be drawn.

By default, a Graphics2D uses a solid stroke with a width of 1. In the previous Iguana example, the line width is changed just before the outline of the rounded rectangle is drawn, like so:

g2.setStroke(new BasicStroke(4));