Advanced Android App Life cycle

8/12/2019 Advanced Android App Life cycle

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App Lifecycle +

Advanced Architectures/Patterns/ProblemsAndroid


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bryan costanichem: [email protected]: @bryancostanich

slides: slideshare.net/bryancostanich

code: bit.ly/1avqivC
http://slideshare.net/bryancostanichhttp://bit.ly/1avqivChttp://bit.ly/1avqivChttp://slideshare.net/bryancostanich


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What We'll Cover

Review Activity Lifecycle Relation to the App

Lifecycle

Review States + Important

Events Background Updates

Configuration Changes

App Lifecycle + PatHandling

App Initialization

Application Crash

Restarts Asynchronous Init


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Activity LifecycleImportant Methods

OnCreate ( ) - Initialize StufOnResume ( ) - Begin Life

OnPause ( ) - Stop/Pause


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Code Walkthrough 1Activity Lifecycle


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App InitializationCommon to need to initialize things at the beginning of the App Li

Sometimes these can take a whileCommon approach is to show a loading screen


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Pattern: AppSingletonApp Singleton Class

bool IsInitialized PropertyInitialized Event

ActivityBase

Check to see if App.Current.IsInitialized

Ap

public static

App()protected - c

()public static A

Currentpublic bool

IsInitializedpublic event

Initialized


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Code Walkthrough 2App Initialization


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App Initialization After Cras

Unhandled Exceptions will cause Android to kill the process

AppDomain and all objects in it will be cleaned up by Mono

Android will still attempt to launch last running activity

If it relies on initialization, activity wont make sense

If activity re-launch fails, it moves backwards through the nav

history - Painful

Need to enable initialization on all activities

Sometimes want to force load of launch activity


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Code Walkthrough 3App Initialization, Post-Crash


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Unhandled Exceptions

In other app platforms, can be handled at an App leve

AppDomain.CurrentDomain.UnhandledException +=

HandleUnhandledException;

Trickier in Android - Will cause a Spectacular Crash

Some day, this story will be better, can at least log no

See in Android Log


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Code Walkthrough 4

protected void HandleUnhandledException (objectsender,

UnhandledExceptionEventArgsargs){

Exceptione = (Exception) args.ExceptionObject;

Console.WriteLine ("Unhandled Exception = " + e.Message);

}


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Waiting for Async Initializat

Sometimes app needs to wait for multiple asynchrono

e.g.: binding to more than one service

or service + web request

etc.

Same pattern as before, but keep track of inits

When all inits complete, raise Initialized event


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Code Walkthrough 5Asynchronous Initialization


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Documents

Advanced Android App Life cycle