Services allow applications to perform long-running operations in the background without providing a user interface. Broadcast receivers allow applications to register to receive intents for various system-wide or application events. When a broadcast is sent, all registered receivers are notified. Services run indefinitely until stopped, while broadcast receivers are temporary and only active while handling a broadcast. Both services and broadcast receivers allow applications to perform tasks outside of activities.

1. Android Programming
Lesson 11
Services and Broadcast
Receivers
NGUYEN The Linh

2. Android Programming
Contents
1 Android Services
2 Broadcast Receivers
3 Services and Broadcast Receivers
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3. Android Programming
Services and Broadcast Receivers
Android Services
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4. Android Programming
Android Services
 What is a service?
Download the
file in the
background.
Keeps playing
song in the
background
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5. Android Programming
Android Services
 What is a service?
 A Service is an application component that can perform long-
running operations in the background and does not provide a user
interface.
 A Service can run in the background to perform work even while
the user is in a different application.
 A Service runs in the main thread of the application that hosts it,
by default.
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6. Android Programming
Android Services
 What is a service?
 This means that, if your service is going to do any CPU intensive
work or blocking operations (such as MP3 playback or
networking), you should create a new thread within the service to
do that work.
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7. Android Programming
Android Services
 Creating a service
 To create a service, you must create a subclass of Service.
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8. Android Programming
Android Services
 Creating a service
 Now we will override two more methods: onStart and onDestroy
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9. Android Programming
Android Services
 Creating a service
 Necessary to let the AndroidManifest file know about your
service <service android:enabled="true"
android:name=".DemoService" />
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10. Android Programming
Android Services
 Starting a Service
 The application can start the service with the help of
Context.startService method. The method will call the onCreate
method of the service if service is not already created; else
onStart method will be called.
 Context.startService() | ->onCreate() – >onStartCommand()
[service running]
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11. Android Programming
Android Services
 Stopping a service
 The service started with startService method will keep on running
until stopService() is called or stopSelf() method is called.
 context.stopService() | ->onDestroy() [service stops]
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12. Android Programming
Android Services
 Stopping a service
 It's important that your application stops its services when it's done
working, to avoid wasting system resources and consuming
battery power.
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13. Android Programming
Android Services
 Service Life Cycle
 The lifecycle of a service is much simpler than that of an activity.
However, it's even more important that you pay close attention to
how your service is created and destroyed, because a service can
run in the background without the user being aware.
 The service lifecycle—from when it's created to when it's
destroyed—can follow two different paths:
• A started service
• A bound service
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14. Android Programming
Android Services
 Service Life Cycle
Runs indefinitely
stopService()
startService()
Service
stopSelf()
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15. Android Programming
Android Services
 Service Life Cycle
bindService()
Service
unbindService()
when all of them unbind
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16. Android Programming
Android Services
 Service Life Cycle
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17. Android Programming
Android Services
 Example 11.1
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18. Android Programming
Services and Broadcast Receivers
Broadcast Receivers
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19. Android Programming
Broadcast Receivers
 What is a broadcast receiver?
 A broadcast receiver is an Android component which allows to
register for system or application events. All registered
receivers for an event will be notified by Android once this event
happens.
 For example Android allows that applications can register for
the ACTION_BOOT_COMPLETED which is fired by the system
once the Android system has completed the boot process.
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20. Android Programming
Broadcast Receivers
 What is a broadcast receiver?
Application 1 Application 2
BroadcastReceiver-1 BroadcastReceiver-1 BroadcastReceiver-3
Filter-2 Filter-1 Filter-2
Service-1 Service-2
Filter-1 Filter-2
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21. Android Programming
Broadcast Receivers
 Registering a broadcast receiver?
 To create a broadcast receiver, you must create a subclass
of BroadcastReceiver
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22. Android Programming
Broadcast Receivers
 Registering a broadcast receiver?
 Register a Receiver dynamically in java code.
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23. Android Programming
Broadcast Receivers
 Registering a broadcast receiver?
 Or let the AndroidManifest file know about your receiver
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24. Android Programming
Broadcast Receivers
 BroadcastReceiver life cycle?
Get notified when Intent happens
Android Broadcast
System Receiver
Registers for certain intents
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25. Android Programming
Broadcast Receivers
 Example 11.2
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26. Android Programming
Services and Broadcast Receivers
Services and Broadcast Receivers
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27. Android Programming
Services and Broadcast Receivers
Services-1 Broadcast
Receiver-1
Filter-1
Activity Broadcast
Receiver-2
Filter-2
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28. Android Programming