7.1. Test Your Application

You've probably been developing your application using the Android Emulator that is part of the Android Developers Kit. If you haven't already done so, take the time to load your application on a real Android device (such as the T-Mobile G1 phone), and test the application again. The emulator is very good, but there are a number of things that can be different between the desktop emulation and a real device:

Screen resolution

The Android SDK emulates a device like the T-Mobile G1, with a half VGA screen (320x480), roughly 3.2 inches in diagonal measure. Real Android devices will have a variety of screen shapes, sizes, and resolutions, so you need to know how your application will function on those different devices.

Screen orientation

The SDK emulates only portrait mode, with the screen taller than it is wide. Many Android devices (including the T-Mobile G1) support switching screen orientation, and you need to be sure your application behaves appropriately in all orientations.

Touchscreen operation

The emulator uses mouse clicks and movements to mimic the touchscreen on a real device, but there's nothing like a real touchscreen. On a real device you can get a much better sense of what it will be like for users to interact with your application.

CPU and network performance

On the emulator, you are using your PC or Mac to emulate an ARM processor. The application's speed is tied to the speed of your underlying host processor, which typically consists of multiple multigigahertz multiprocessors. If your application is at all performance sensitive, you'll want to see how it functions on real devices. Similarly, the emulator is using your host's network connection, which may be broadband, to access the Internet. On a real device your network connection will either be WiFi or a mobile network (GPRS, EDGE, HSPA, or 3G, depending on your location), and the connection's speed and latency will be changing as the phone moves around. You want to know how these factors affect the operation of your application, and how it appears to the user.

The emulator is quite flexible, and some of these things can be tested to some degree by manipulating the emulator setup in DDMS (see Section 5.2.5 for more about DDMS). But again, it is important to stress that nothing can replace testing on real Android devices.