Android How to Program, 3/e

6.1 Introduction

The Cannon Game1 app challenges you to destroy nine targets before a ten-second time limit expires (Fig. 6.1). The game consists of four types of visual components—a cannon that you control, a cannonball, nine targets and a blocker that defends the targets. You aim and fire the cannon by touching the screen—the cannon then aims at the touched point and fires the cannonball in a straight line in that direction.

1. We’d like to thank Prof. Hugues Bersini—author of a French-language object-oriented programming book for Éditions Eyrolles, Secteur Informatique—for sharing with us his suggested refactoring of our original Cannon Game app. We used this as inspiration for our own refactoring in the latest versions of this app in this ...