Running and Debugging Applications
To build and debug an Android application, you must first configure your project for debugging. The ADT plug-in enables you to do this entirely within the Eclipse development environment. Specifically, you need to do the following:
- Create and configure an Android Virtual Device (AVD).
- Create an Eclipse debug configuration for your project.
- Build the Android project and launch the emulator with the AVD.
When you complete each of these tasks, Eclipse attaches its debugger to the Android emulator (or Android device connected via USB), and you are free to run and debug the application as desired.
Managing Android Virtual Devices
To run an application in the Android emulator, you must configure an Android Virtual Device (AVD). The AVD profile describes the type of device you want the emulator to simulate, including which Android platform to support. You can specify different screen sizes and resolutions, and you can specify whether the emulator has an SD card and, if so, its capacity. In this case, a slightly modified AVD for the default installation of Android 2.3.3 will suffice. Here are the steps for creating a basic AVD:
- Launch the Android Virtual Device Manager from within Eclipse by clicking on the little Android icon with the bugdroid in mini-phone ) on the toolbar. You can also launch the manager by selecting Window, AVD Manager in Eclipse.
- Click the New button to create a new AVD.
- Choose a name for the AVD. Because you are going to take all the defaults, name this AVD KindleFire-Portrait.
- Choose a build target. The Kindle Fire is based on API Level 10, Android 2.3.3.
- Choose an SD card capacity, in either kibibytes or mibibytes. (Not familiar with kibibytes? See this Wikipedia entry: http://goo.gl/N3Rdd.)
- Choose a skin. This option controls the different visual looks of the emulator. In this case, we use the effective resolution of the Kindle Fire screen of 600 pixels wide and 1004 pixels high (the default portrait resolution). Alternately, we could create an AVD for landscape mode, where we’d need to use 1024 pixels wide and 580 pixels high. The Kindle Fire reserves some space for a soft key menu.
- Under Hardware, change the Abstracted LCD density to 169 and change the Device ram size to 512 to better emulate the Kindle Fire device characteristics.
- Optionally enable the Snapshot feature. This allows you to save and restore the state of an emulator session, dramatically improving the speed with which it launches.
- Your project settings should look like what’s shown in Figure 1.6.
Figure 1.6. Creating a New AVD in Eclipse
- Click the Create AVD button and wait for the operation to complete. This may take a few seconds if your SD card capacity is large, because the memory allocated for the SD card emulation is formatted as part of the AVD creation process.
- Check the Snapshot checkbox to enable much faster emulator restart times at the expense of some storage space.
- Click Finish. You should now see your newly created AVD in the list.
Creating Debug and Run Configurations in Eclipse
You are almost ready to launch your application. You have one last remaining task: You need to create a Debug configuration (or Run configuration) for your project in Eclipse. To do this, follow these steps:
- In Eclipse, choose Run, Debug Configurations from the menu or, alternately, click the drop-down menu next to the Debug icon () on the Eclipse toolbar and choose the Debug Configurations... option.
- Double-click the Android Application item to create a new entry.
- Edit that new entry, currently called New_configuration.
- Change the name of the configuration to HelloKindleDebug.
- Set the project by clicking the Browse button and choosing the HelloKindle project.
- On the Target tab, check the box next to the AVD you created.
- Apply your changes by clicking the Apply button. Your Debug Configurations dialog should look like Figure 1.7.
Figure 1.7. The HelloKindleDebug Debug Configuration in Eclipse
Launching Android Applications Using the Emulator
It’s launch time, and your application is ready to go! To launch the application, simply click the Debug button from within the Launch Configuration screen, or you can do it from the project by clicking the little green bug icon () on the Eclipse toolbar. Then, select HelloKindleDebug debug configuration from the list.
After you click the Debug button, the emulator launches (see Figure 1.8). This can take some time, so be patient.
Figure 1.8. The Android Emulator Home Screen
Now, the Eclipse debugger is attached, and your application runs, as shown in Figure 1.9.
Figure 1.9. The Application Running
As you can see, the application is simple. It displays a single TextView control with a line of text. The application does nothing else.
The emulator’s home screen doesn’t look anything like the home screen on a real Kindle Fire device, because it has been redesigned by Amazon. Among other things, this means the emulator won’t work for full application testing. You need to get a real Kindle Fire device for that.
Controlling the Emulator
When you create an AVD in this way, it will not have the keyboard and control buttons to the left of the screen, like you might be used to with the default emulators. All the commands are available through your development machine keyboard. For example, the Home key maps conveniently to the Home key. The menu key maps to F2 or Page-Up. Search maps to F5. Back maps to Esc. There are many more; find them in the Android documentation at http://goo.gl/5DMiI.
Debugging Android Applications Using DDMS
In addition to the normal Debug perspective built into Eclipse for stepping through code and debugging, the ADT plug-in adds the DDMS perspective. Although you have the application running, take a quick look at this perspective in Eclipse. You can get to the DDMS perspective (see Figure 1.10) by clicking the Android DDMS icon () in the top-right corner of Eclipse. To switch back to the Eclipse Project Explorer, simply choose the Java perspective from the top-right corner of Eclipse.
Figure 1.10. The DDMS Perspective
The DDMS perspective can be used to monitor application processes, as well as interact with the emulator. You can simulate voice calls and send SMS messages to the emulator. You can send a mock location fix to the emulator to mimic location-based services. You learn more about DDMS and the other tools available to Android developers in Chapter 2, “Mastering the Android Development Tools.”
The LogCat logging tool is displayed on both the DDMS perspective and the Debug perspective. This tool displays logging information from the emulator or the device, if a device is plugged in via USB.
Launching Android Applications on a Device
It’s time to load your application onto a real Kindle Fire device. To do this, you need to connect the Kindle Fire into your computer using a USB data cable. Make sure that you have your machine configured for Kindle Fire debugging.
To ensure that you debug using the correct settings, follow these steps:
- In Eclipse, from the Java perspective (as opposed to the DDMS perspective), choose Run, Debug Configurations.
- Single-click HelloKindleDebug Debug Configuration.
- On the Target tab, change Deployment Target Selection Mode to Manual. You can always change it back to Automatic later, but choosing Manual forces you to choose whether to debug within the emulator (with a specific AVD) or a device, if one is plugged in via USB, whenever you choose to deploy and debug your application from Eclipse.
- Apply your changes by clicking the Apply button.
- Plug a Kindle Fire device into your development computer using a USB cable.
- Click the Debug button within Eclipse. The dialog shown in Figure 1.11 appears, showing all available configurations for running and debugging your application. All physical devices are listed, as are existing emulators that are running. You can also launch new emulator instances by using other AVDs you have created.
Figure 1.11. Choosing an Application Deployment Target
- Choose the available Kindle Fire device. If you do not see the Kindle Fire listed, check your cables and make sure that you installed the appropriate drivers.
Eclipse now installs the Android application onto your Kindle Fire, attaches the debugger, and runs your application. Your device shows a screen similar to the one you saw in the emulator. If you look at the DDMS perspective in Eclipse, you see that logging information is available, and many features of the DDMS perspective work with physical devices and the emulator, such as taking a screenshot (see Figure 1.12).
Figure 1.12. The Application Running on a Kindle Fire