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Android Studio 4.1 Development Essentials – Java Edition
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39.4 Testing the Observer
Since the DemoObserver class outputs diagnostic information to the Logcat console, it will be easier to see the output if a filter is configured to display only the DemoObserver messages. Using the steps outlined previously in “Android Activity State Changes by Example”, configure a filter for messages associated with the DemoObserver tag before running the app on a device or emulator.
On successful launch of the app, the Logcat output should indicate the following lifecycle state changes and events:
onCreate
CREATED
onStart
STARTED
onResume
RESUMED
With the app still running, perform a device rotation to trigger the destruction and recreation of the fragment, generating the following additional output:
onPause
STARTED
onStop
CREATED
onDestroy
DESTROYED
onCreate
CREATED
onStart
STARTED
onResume
RESUMED
Before moving to the next section in this chapter, take some time to compare the...
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