For that, you need to create a Thread . Add a Thread to the original source code, StopWatch.java , to display the elapsed time in seconds. The elapsed time won't be very accurate anyway, so just show the integral number of seconds. You only need to set the text a few times per second. The applet at the end of Section 7.8 shows animations of moving symmetric patterns that look something like the image in a kaleidascope.
Symmetric patterns are pretty.
Make the SimplePaint3 applet do symmetric, kaleidascopic patterns. As the user draws a figure, the applet should be able to draw reflected versions of that figure to make symmetric pictures. The applet will have several options for the type of symmetry that is displayed. The user should be able to choose one of four options from a Choice menu. Formulas for computing the reflections are given below.