Android 2

Learn more about android

intent filter

each activity describes the intents it offers in the app manifest file (XML). when an app requests an activity, it issues a startActivity() call requesting an intent

how does android handle the “what is being done” part

using a registry of intents

intent

messaging object used to request an action from another app component

open intent pro 1

new features can be added after design

open intent pro 2

loose coupling

open intent con 1

no guarantees

open intent con 2

there may be no provider capable of providing the open intent desired function

service providing intent example

text to speech provider. different instances for different languages, speech styles, voices, etc

discovery start

at installation, each new app registers its intents with the OS. new providers become known when they’re installed

lifecycle

each activity has a defined lifecycle delimited by calls to event handlers

android issue 1

no provider for an intent

android solution 1

don’t offer the option to the user

android issue 2

many possible providers

android solution 2

ask the user to choose

android issue 3

component crashes

android solution 3

revert to the calling activity/ fail/ home screen