Android Programming

Yong Heui Cho @ Mokwon University

2

Context• Interface to global information

about an application environment• Uses of context– Creating new objects– Accessing standard common

resources– Accessing components implicitly

Activity

Context

OS

3

Access of Context• this– Activity extends Context

• View.getContext()– Context for View (usually Activity

Context)• Activity.getApplicationContext()– Permanent Application Context

• ContextWrapper.getBaseContext()– Access to another Context

4

Bundle vs. Parcel• Bundle– A mapping from String values to various

Parcelable types

• Parcelable– Interface for classes whose instances can be

written to and restored from a Parcel

• Parcel– Container for a message (data and object

references) that can be sent through an IBinder

5

ContactsContract• Contract between the contacts

provider and applications• Context.getContentResolver()• Cursor: interface of results for

database query

Content Provider

Contacts Provider

Activity

Context

OS

getContentResolver()

ContactsContract

6

Telephony Manager• Access to the telephony APIs is managed by

the Telephony Manager.– Monitor phone state– Retrieve incoming phone numbers– Observe changes to data connections, signal

strength, and network connectivity

7

PhoneStateListner• Monitors changes in specific telephony

states on the device, including service state, signal strength, message waiting indicator (voicemail).

Activity

Context

PhoneStateListener

OS

TelephonyManager

listen()

8

Incoming Phone Calls• Service

– an application component representing either an application's desire to perform a longer-running operation while not interacting with the user or to supply functionality for other applications to use

• IntentFilter– Structured description of Intent values to be matched– Context.registerReceiver(BR, IntentFilter)– Context.unregisterReceiver(BR)

Activity

Context

OS

Service

broadcastIntent

BroadcastReceiver brTx

Context

registerReceiver() with IntentFilter

9

Receiving Call• Permission–<uses-permission

android:name="android.permission.READ_PHONE_STATE" />Activity

Context

OS

Service

Intent

PhoneStateListener rxListener

Context

TelephonyManager

listen()

10

Sending SMS• SmsManager

–  SmsManager.getDefault().sendTextMessage(phoneNum, null, msg, piSent, piDelivered);

• PendingIntent– a description token for a foreign application to allow the

foreign application to use our application's permissions– Action → Intent → PendingIntent(for broadcast)

Activity

Context

BroadcastReceiver brSend

OS

SmsManager

broadcastBroadcastReceiver

brDeliever

registerReceiver() with IntentFilter

PendingIntent

11

Receiving SMS• Receiving process

– Broadcast → Intent → Bundle → PDU (Object[]) → SmsMessage → String

• Bundle: a mapping (or dictionary) class from String key to various types

• PDU: Protocol Description UnitActivity

Context

BroadcastReceiver brReceive

OS

SmsManager

Intent via broadcast

registerReceiver() with IntentFilter

12

Bluetooth Setup• BluetoothAdapter (my device)• BluetoothDevice (partner devices)• void onActivityResult(int requestCode, int resultCode,

Intent data)• Parcelable Intent::getParcelableExtra(String)

Activity

Context

BroadcastReceiver brBluetooth

My OS

BluetoothAdapter- getDefaultAdapter()- isEnabled()- startDiscovery()- cancelDiscovery()

Intent via broadcastregisterReceiver() with IntentFilter

BluetoothDevice- getName()- getAddress()

Partner OS

Bluetooth