Chapter 1: The Android Sensor Ecosystem
Chapter Project: PhoneCheckup — Device Health Diagnostic
By the end of this chapter, you will build PhoneCheckup — an app that discovers all available sensors on any Android device, runs interactive diagnostic tests, and generates a health report card. People use this app when buying or selling used phones, or when troubleshooting device issues.
1.1 Why Sensors Matter in Modern Android Apps
Pick up your phone and tilt it. The screen rotates. Walk down the street and your fitness app counts every step. Open your banking app and your fingerprint unlocks it. Point your camera at a QR code on a restaurant table and the menu appears. Every single one of these interactions is powered by sensors.
