Lecture 15: Introduction to Broadcasts

Question 1

Broadcasts in Android are a way of ____

Answer 1

notifying other applications or activities that some kind of event has taken place

Question 2

The Android system itself uses broadcasts to notify applications when ___

Answer 2

system events have taken place

Question 3

Applications may set up ___ to read broadcasts and ___ to send them

Answer 3

Applications may set up ___ to read broadcasts and ___ to send them

Question 4

The most common purpose of a broadcast receiver is to receive __ notifications

Answer 4

system level

Question 5

Introduction to Broadcasts

Answer 5

• ACTION_BATTERY_LOW
• ACTION_CHARGING
• ACTION_HEADSET_PLUG
• ACTION_USB_ACCESSORY_ATTAHED
• ACTION_DATE_CHANGED

Question 6

Write code to declare a broadcast receiver in the app manifest

Answer 6

<receiver>
<intent-filter>
<action></action>
</intent-filter>
</receiver>

Question 7

The broadcast receiver takes an ___, which in turn names an __ that we will be “listening” for

Answer 7

• intent filter
• action

Question 8

____ is required if using external broadccasts, if only listening for internal broadcasts this can be ___

Answer 8

• exported=true
• false

Question 9

Once the receiver has been declared in the app manifest, you can make a ___ for the receiver. It overrides one method called onReceive which ___

Answer 9

• Java Class
• opens an activity and displays a toast popup

Question 10

Manifest-declared receivers can ____ when they receier a ___

Answer 10

• wake up
• broadcast

Question 11

Manifest-declared receivers are always ___ for broadcasts

Answer 11

listening

Question 12

_____ receivers cant be turned off and will aways trigger

Answer 12

Manifest-declared

Question 13

Receivers are __ on application install and then treated as separate ___ for your application

Answer 13

• registered
• launching entrypoint

Question 14

When a broadcast is made and caught by the receiver, ___

Answer 14

the OnReceive method is called and the broadcast receiver is “active”

Question 15

Once the OnReceive method resolves, the receiver ___

Answer 15

returns to its dormant “waiting” state

Question 16

You can declare a broadcast receiver without any manifest entry, this known as a ___, as its registered with the ___

Answer 16

• context-registered receiver
• current context

Question 17

Context-registered receivers exist only for as long as the ___ exists

Answer 17

containing context

Question 18

You can declare a broadcast receiver without any manifest entry, this is known as a ___, as its registered with the ___

Answer 18

• context-registered receiver
• current context

Question 19

To declare a context-registered receiver, you need to create an instance of the ___ and call the ___ with a ___

Answer 19

• Receiver class
• registerReceiver()
• context, the receiver, an intent filter, and an exported flag

Question 20

Both contextual and manifest registered receivers can use the same underlying declared ___ and both will call the overridden ___ method when a ___

Answer 20

• Broadcast Receiver
• OnReceive()
• broadcast is received

Question 21

Contextually registered receiver will disappear and ____ when the context disappears, while the manifest registered receiver will ___

Answer 21

• stop listening
• always listen

Question 22

To close an existing context-registered receiver you call ___ and pass it the ___

Answer 22

• unregisterReceiver()
• BroadcastReceiver object

Question 23

When closing a context-register receiver, you will close all ___ and ___ of the receiver class that have been registered. You cannot selectively deregister ___ receiver from the ___

Answer 23

• intent filter
• exported flag versions
• one
• underlying class

Question 24

Generally you dont need any ___ to listen to most normal system level broadcasts

Answer 24

special permissions

Question 25

The broadcast space should be considered ___

Answer 25

global

Question 26

To avoid apps doing malicious ats through sending broadcasts, Android lets you apply __ when receiving or sending broadcasts

Answer 26

optional permissions

Question 27

___ can demand the broadcasts have necessary permission, while ___ can demand that receivers have a necessary permission

Answer 27

• Receivers
• Broadcaster

Question 28

Besides permissions another danger that comes to working with broadcast receivers (particularly manifest-registered receivers) is ___

Answer 28

performance

Question 29

If a particular broadcast action has many receivers listening to it that action may result in ___

Answer 29

multiple apps being launched at once from those receivers

Question 30

___ receivers are preferred where possible to help limit potential performance issues

Answer 30

Context-registered