This document discusses BroadcastReceivers in Android. A BroadcastReceiver is an intent-based publish-subscribe system that allows apps to receive system events like SMS messages. BroadcastReceivers can receive and react to system broadcasts, broadcasts from other apps, and initiate broadcasts to other apps. They are registered either dynamically in code or statically in the AndroidManifest.xml file. Broadcasts are sent using the sendBroadcast or sendOrderedBroadcast methods and an Intent. Ordered broadcasts are executed in a defined order while normal broadcasts run asynchronously. The BroadcastReceiver object is only valid during the onReceive method call.

1. Android –
BroadcastReceiver
Yong Heui Cho @ Mokwon University
Some of slides are referred to:
[1] Everything of Android, slideshare.

2. 2
Broadcast Receiver
• An Intent-based publish-
subscribe mechanism.
• Great for listening system
events such as SMS messages.
□ Courtesy to Everything of Android, slideshare.

3. 3
Uses of BR
• A broadcast receiver is a component that
does nothing but receive and react to
broadcast announcements
• Your app can
– Receive and react to system services (example:
battery low)
– Receive and react to other apps broadcast
announcements
– Initiate broadcasts to other apps
□ Courtesy to Everything of Android, slideshare.

4. 4
Register of BR
• To register Broadcast Receiver, you can
– Dynamically register with registerReceiver (in
code)
– Using <register> tag in AndroidManifest.xml
□ Courtesy to Everything of Android, slideshare.

5. 5
Send of Broadcast
• Broadcast is sent using Intent and
sendBroadcast or sendOrderedBroadcast
methods
• Example:
– Intent intent = new
Intent(“com.enlume.MSG_PRO");
sendBroadcast(intent);
□ Courtesy to Everything of Android, slideshare.

6. 6
Normal vs. Ordered
• Normal Broadcasts
– Sent with sendBroadcast. All broadcasts are
run in undefined order, often at the same
time.
• Ordered Broadcasts
– Sent with sendOrderedBroadcast. Each
receiver executes in turn. Possible to
propagate a result to next receiver. Order can
be controlled using android:priority tag.
□ Courtesy to Everything of Android, slideshare.

7. 7
BR Lifecycle
• Broadcast Receiver object is valid only for
the duration of the onReceive(Context,
Intent) method.
– You cannot do anything asynchronous in
here!
– Except you can start a service, which can start
a thread.
□ Courtesy to Everything of Android, slideshare.

8. 8
Event Listener
• Interface to process specific events

9. 9
BR vs. Listener
type BroadcastReceiver Listener
goal class for Intents
class or interface
for Intents &
others
message
mostly global
messages
mostly specific
messages
period
discontinuous
reception
frequent (or
continuous) reception
construction
static (manifest) or
dynamic
dynamic only