Iat 381 Final

Front 1

whats earlier mobile?

Back 1

- a piece of stone/clay with markings

- Papyrus scroll & ink pen

- 1800s: printed book

Front 2

whats the mobile platforms?

Back 2

- The Brick: 1983 Motorola

- Apple Newton 1987: vision leading for today, PDA(Personal Digital Assistant)

- Marco, Envoy: 1995 Motorola

Front 3

whats the form factors?

Back 3

- handheld large devices

- palm-sized

Front 4

what is the role of Telecommunication Industry?

Back 4

- combined PDA features with networked applications

- clam shell design; qwerty keyboard

- came out in 2007 (birth year of iPhone)

Front 5

what are some initial innovations?

Back 5

1. lower power mobile processors

2. higher quality displays:

- promising future as gaming & multimedia capable devices

- eased the disappearance of the hardware keyboard

- evolution to multi-touch screens

Front 6

what are some initial technologies?

Back 6

1. low power, meter accuracy GPS technologies that enabled and fueled location based services

2. embedded sensors that optimize the platform operation (compass, proximity & acceleration) and provides higher level services to users (camera, light)

Front 7

what is the software architecture?

Back 7

Front 8

what is android?

Back 8

- mobile operating system + app framework

Google

- develops & extends the Android OS

- distributes the android OS and developer tools

- runs Goolge Play (Android app market)

Front 9

what type of devices can Android run on?

Back 9

multi-platform

- android wear: watches

- android tv: apps, games

- android auto: entertainment & navigation

Front 10

android versions

Back 10

Front 11

the Android Architecture

Back 11

- operating system is based on Linux that is specifically designed to be run on mobile devices

- complete application framework allows us to create & deploy our own custom apps

1. Linux Kernel

2. Libraries & Android runtime

3. Application Framework

4. Applications

Front 12

Android Architecture : Linux Kernel

Back 12

Linux itself & set of drivers

eg: audio, camera, display, keypad, power

Front 13

Android Architecture : Libraries + Android runtime

Back 13

- set of core libraries built in C++

eg: graphics, databases

- virtual machine that run in its own box

Front 14

Android Architecture : application framework

Back 14

modules for controlling different components of an app

eg: activities(screen), content providers (mange data, move data between apps), location, notifications

Front 15

what is part of Application Components?

Back 15

1. activities

2. services

3. broadcast receivers

4. content providers

Front 16

Application Components : activities

Back 16

- screens: made up of views

- multiple views arranged into layouts

Front 17

Application Components : services

Back 17

-perform a background job

- usually do not have a visual component

Front 18

Application Components : broadcast receivers

Back 18

- react to system messages

- react to messages from other apps

Front 19

Application Components : content providers

Back 19

- managed access to data

- apps exchange data with each other

Front 20

what is Android Studio?

Back 20

new Android development environment based on IntelliJIDEA

Front 21

Android Development Environment: android studio

Back 21

- emulator

- virtual device manager

- android device monitor(DDMS)

- interface of android studio

- logcat

Front 22

Android Studio : Emulator

Back 22

a virtual device that display the software version of device

pros: conveniently test app on various hardware/screen sizes

cons: missing features/hardware for sensing GPS, camera, video recording

Front 23

Android Studio : AVD manager

Back 23

Android Virtual Device Manager

Front 24

Android Studio : Android Device Monitor(DDMS) debug

Back 24

stand-alone tool that provides a graphical user interface for several Android application debugging & analysis tools

Front 25

Android Studio : LogCat debug

Back 25

log message at runtime with Log class for debugging

uses memory & CPU resources

Front 26

Android project structure

Back 26

- manifest: app name, app activities

- java code: programming logic

- resource folder

Front 27

what is an activity?

Back 27

an application component that provides a screen

an app can have many screens/activities, with one main activity

Front 28

why is the lifecycle important?

Back 28

know if the activity is visible to user, paused/stopped

Front 29

activity life-cycle (methods)

Back 29

onCreate, onStart, onResume: launch app for the first time

onPause, onStop: move from one activity to another activity

onRestart, onStart, onResume: back button

onDestroy: kills activity due to low memory, manually finish the activity

Front 30

Activity life-cycle states

Back 30

Front 31

device orientation changes

Back 31

every time the device orientation changes, the activity life-cycle is destroyed & recreated

the system will automatically save its instance state in a bundle object

Front 32

saving the activity state & restore

Back 32

consider what the state is the activity in when orientation changes

although the activity has been paused, stopped and destroyed, and then recreated, after orientation change, all information should be kept

- onSaveInstanceState()

- onRestoreInstanceState()

* although these are called automatically by system, it is good to add Log to keep track

Front 33

onSaveInstanceState

Back 33

- save temporary information, variable values before calling onPause

- triggered right after onPause

Front 34

onRestoreInstanceState

Back 34

- restore temporary information, variable values

- triggered right after onStart

Front 35

Back Button exception

Back 35

when back button is pressed, Android system assumes that the activity is no longer needed, and destroy it, information cant be restored

Front 36

Bundle variable

Back 36

provide key (unique id) with value for temporary data

*same Bundle is received after the activity is been restored after destroying

Front 37

what is context?

Back 37

interface to global information about an application environment

Front 38

using application context

Back 38

Front 39

how to retrieve application context?

Back 39

using Contextcontext = getApplicationContext();

Front 40

how to retrieve application resources?

Back 40

using getResources() with a resource's identifier (ID)

Stringgreeting = getResource().getString(R.string.hello);

Front 41

how to access application preferences?

Back 41

using getSharedPreferences() to retrieve simple application data

Front 42

what is app resources?

Back 42

resources defined by the developer within the Android project files and are specific to the application

Front 43

what is system resources?

Back 43

it is common resources defined by the Android platform and accessible to all applications through the Android SDK

Front 44

how to accessing application resources?

Back 44

can be accessed programmatically using the generated classfile called R.java with getResources()

Front 45

how to access system resources?

Back 45

access by (android.R.string) for words such as OK, Cancel, Yes, No, Cut, Copy & Paste

Front 46

what are simple resource values?

Back 46

1. /res/values/strings.xml - display text

2. /res/values/colors.xml - applied to screen controls

3. dimensions

Front 47

other types of resources

Back 47

- string array

- menus

- animation sequences

- shape drawables

- style & themes

- custom layout controls

Front 48

UI controls : button & button click event

Back 48

when button clicked, Android system receives the event, only the listener is interested in reacting to the event

Front 49

UI controls : view structure

Back 49

Front 50

view structure : view

Back 50

object, occupies a rectangular area on screen & is responsible for handling events (TextView, EditView, etc)

Front 51

view structure : view group

Back 51

occupies rectangular area on screen, is invisible & holds other views in a certain structure (vertically, horizontally, grid, ect)

Front 52

UI controls : linear layout

Back 52

xml: all Views & ViewGroups are placed in 1 ViewGroup which is the root of the View hierarchy

orientation: 2 modes

-horizontal same column

-vertical same row

Front 53

linear layout : root view

Back 53

width & height usually set to match_parent, to fill up all available space

Front 54

linear layout attributes : layout_weight

Back 54

2 components: any values >= 1, as long as the other component does not have a value for layout_weight

Front 55

linear layout attributes : layout_weight

Back 55

more components: decide the priority/importance of 1 component vs. the other

Front 56

linear layout attributes : layout_gravity

Back 56

controls the place where the view is situated in the layout (outside of the view)

*will not change the column/row

Front 57

linear layout attributes : gravity

Back 57

controls where the contents of the view should appear inside the view

*no effect if wrap_content

Front 58

UI controls : ListView

Back 58

ListView Concept

Front 59

ListView : creating

Back 59

Front 60

What is the use of Adapter?

Back 60

it manages the data by accessing the data and display it in a view (ListView, GridView, Spinner, etc)

Front 61

how many types does adapter have?

Back 61

adapter types are related to data source

1. array adapter: data from array

2. cursor adapter: data from cursor(database)

3. base adapter: custom data

Front 62

what is Intents?

Back 62

asynchronous messaging mechanism that allow Android components to request functionality from other components of the Android system

Front 63

what is Explicit Intents?

Back 63

it explicitly define the component name which should be called by the Android system, by using the java class as identifier

Front 64

what is Implicit Intents?

Back 64

it specify the action which should be performed, & it can start any component that can handle the intended action

Front 65

what happens when there are many components registered for a specific action and the data type in implicit intents?

Back 65

it searches for all components that are registered for the specific action and the data type

- one component found: it is started directly

- several component: the user will get a selection dialog and can decide which component should be used for the intent

Front 66

how do start other components using intent?

Back 66

activities: startActivity(Intent);

services: startService(Intent);

Front 67

sending user to another app

Back 67

it depends on the action (view, edit, send) and intents often include data, might be Uri (address, email message)

Front 68

how to put extra data in intent?

Back 68

putExtra()

* if there is no Uri, declare "text/plain"

Front 69

verification if there is app to receive your intent

Back 69

queryIntentActivities():

returns a list of activities able to handle the action intent

* check before starting the activity

Front 70

how do you retrieve result data from called activity?

Back 70

retrieve by calling startActivityforResult() using REQUEST code, after startActivity() is called

the onActivityResult on the sending activity is called

Front 71

what is request code?

Back 71

this is the argument that identifies the request for the result

*maps the returning result from intent

Front 72

result code

Back 72

result code is specified by the second activity

RESULT_OK: if operation was successful

RESULT_CANCELED: operation failed

Front 73

sending data/result to initial activity

Back 73

onActivityResult(request code, result code, result data)

Front 74

how do you receive data?

Back 74

by checking the request code & result code, then use getExtra()

Front 75

what is the process to receive intent?

Back 75

1. create intent: setting up startActivityResult

2. prepare the result to send back (packaging)

3. returning the result: check if the result is okay with request code

Front 76

how to use intent filters?

Back 76

be specific what to filter:

- type of action (ACTION_SEND, ACTION_VIEW, etc)

- data the activity accepts

Front 77

what are the types of built in sensors?

Back 77

1. motion sensors

2. environmental sensors

3. position sensors

Front 78

what data can you get from sensors?

Back 78

raw data, high precision & accuracy

Front 79

motion sensors

Back 79

- acceleration, forces, rotational forces along 3 axes

- accerometers, gravity sensors, rotational vector sensors, gyroscopes

Front 80

environmental sensors

Back 80

ambient air temperature sensors, pressure, illuminations, humidity

Front 81

position sensors

Back 81

- physical position of the device

- orientation sensors, magnetometers

Front 82

what are the guidelines when accessing hardware?

Back 82

check if the device have the sensor to be used first, check at onResume & release the activity after checking

Front 83

Android Sensors Framework

Back 83

1. SensorManager

2. Sensor

3. SensorEvent

4. SensorEventListener

Front 84

sensor related tasks : identifying sensors & sensor capabilities

Back 84

- disable app features that use sensors that are not present on the device

- identify all sensors of a given type & choose the one with optimum performance for your app

Front 85

sensor related tasks : monitor sensor events

Back 85

- acquiring sensor data, sensor event, every time a sensor detects a change in parameter

- name of sensor that triggered the event, time-stamp, accuracy of event raw sensor data that triggered the event

Front 86

what is the process for working with sensors?

Back 86

1. determine which sensors are available

2. determine an individual sensor's capabilities

3. acquire raw sensor data

4. register sensor event listener at onResume, unregister at onPause

Front 87

how to identify sensors & capabilities?

Back 87

get a reference to the sensor device & get an instance of the SensorManager class:

private SensorManager mSensorManager;

...

mSensorManager = (SensorManager)getSystemService(Context.SENSOR_SERVICE);

then get a listing of every sensor on the device:

ListdeviceSensors=mSensorManager.getSensorList(Sensor.TYPE_ALL);

Front 88

checking for certain sensor

Back 88

Front 89

monitoring sensor events : onAccuracyChanged

Back 89

accuracy changes, provides a reference to the Sensor object that changed, and the new accuracy value

called whenever the accuracy of a given sensor changes

Front 90

monitoring sensor events : onSensorChanged

Back 90

sensor reports a new value, new data, sensor that generated the data, timestamp, accuracy of data

called whenever the values of the sensor change, inspect sensor information

Front 91

adding sensors in manifest

Back 91

indicates which sensors are required by the application

Front 92

acquiring a reference to a sensor

Back 92

using getDefaultSensor in the SensorManager class to acquire raw sensor data

Front 93

rate of sensor data

Back 93

the rate might be high depending on what sensor is used

processing data should not be done in onSensorChanged

Front 94

how to determine device orientation with sensor?

Back 94

getOrientation of the SensorManager class takes 2 parameters:

rotation matrix & an array of 3 float values (azimuth[z], pitch[x], roll[y])

Front 95

list of system services available

Back 95

- Power service

- keyGuard service

- Vibration service

- Alarm service

- Sensor service

- Audio service

- Telephony service

- Connectivity service

- Wi-fi service

Front 96

system service : power

Back 96

gives information about the power of the system

PowerManager pm=(PowerManager)getSystemService(Context.POWER_SERVICE);

Front 97

system service : vibration

Back 97

manages the vibration service

Vibrator vibrator=(Vibrator)getSystemService(Context.VIBRATOR_SERVICE);

*need android.permission.VIBRATE

Front 98

system service : alarm

Back 98

fires an Intent in the future

AlarmManager as=(AlarmManager)getSystemService(Context.ALARM_SERVICE);

Front 99

system service : telephony

Back 99

interacts with calls

TelephonyManager tm=(TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);

Front 100

system service : connectivity

Back 100

check device network state

String serld = Context.CONNECTIVITY_SERVICE;

ConnectivityManager cm=(ConnectivityManager)Context.getSystemService(serld);

Front 101

system service : wi-fi

Back 101

manages the wi-fi connection

WifiManager wfm=(WifiManager)getSystemService(Context.WIFI_SERVICE);

- check/edit wi-fi connection

- scan for wi-fi networks

- be notified about wi-fi changes

Front 102

what is temporary storage?

Back 102

data storage that is stored in the device temporarily when the app is opened, the data will be removed after the app is closed

Front 103

what is persistent storage?

Back 103

data storage that is stored in the device even after the app is closed, unless the data is been cleared/uninstalled

Front 104

what are some persistent data storage options?

Back 104

1. SharedPreferences

2. Internal Storage

3. external storage

4. SQLite Database

5. Network Connection

Front 105

persistent data storage : SharedPreferences

Back 105

simple primitive data stored as key/value pairs that is private to the app

Front 106

persistent data storage : internal

Back 106

it save files directly on the device's internal storage that contains private files, if the app is uninstalled, files are removed

Front 107

persistent data storage : external

Back 107

the data is readable by anyone since it is stored in a removable storage media (SD card) that have non-removable internal storage

Front 108

persistent data storage : SQLite database

Back 108

structured data that is private to the app

Front 109

what are SharedPrefs?

Back 109

a simplest way of storing data in Android-XML file, it store the value & use the corresponding key to retrieve the value later

Front 110

what kind of data can be stored in SharedPref?

Back 110

only primitive data type, not complex data:

- boolean

- long

- int

- float

- string

Front 111

how do you access the preferences?

Back 111

public SharedPreferences getPreferences(int mode)

public abstract SharedPreferences getSharedPreferences(String name, int mode)

Front 112

modes in preferences

Back 112

Front 113

why should preferences be used?

Back 113

Front 114

what is the steps of storing data using sharedPrefs?

Back 114

1. get a reference to the SharedPreferences object getPreferences/getSharedPreferences

2. call the editor edit()

3. use the editor to add the data with a key putBoolean(), putString(), etc

4. commit editor changed commit()

Front 115

how to view SharedPrefs file?

Back 115

data/data/< package-name > /shared-prefs

Front 116

what are SQLite?

Back 116

language for managing data in relational databses

Front 117

what are the characteristics of SQLite database?

Back 117

apps have their private SQLite databases that is accessible by any class in the app, but not by other apps

the database is self-contained, transaction-based, & there is no server

Front 118

process of programmatically create database

Back 118

Front 119

whats the steps of creating an SQLite database schema?

Back 119

1. define scheme : database name, version, table names, column names

2. create the database : queries to create the database

3. execute queries : insert, update, delete operations

Front 120

how does SQLiteOpenHelper work?

Back 120

implement onCreate() & onUpgrade()

-opens the database if it exists

- creates the database if it does not exist

- updates the database as necessary

Front 121

SQLiteOpenHelper : onCreate

Back 121

this method is called when the database is first created (creation of tables, initial data inside of tables)

Front 122

SQLiteOpenHelper : onUpgrade

Back 122

this method is called whenever the database is updated (drop, add tables, anything that updates the database structure)

Front 123

SQLiteDatabase class

Back 123

an object representing the database that we have just created

Front 124

why nothing happens after you define the schema and created the database?

Back 124

cause the database only gets created when you attempt to access it for the first time, where onCreate & onUpgrage is not been called when there is no access to the database

Front 125

how do you access the database?

Back 125

getWritableDatabase() will return an SQLite database object, a reference to the database that was just created

Front 126

insert query for SQLite

Back 126

creating an object of class ContentValues, it takes a key & a value

Front 127

what is the database code structure?

Back 127

have code that is re-usable & keep separate UI code from database code

Front 128

database code structure : Database class

Back 128

contains a SQLite database instance & helper

Front 129

database code structure : MyHelper class

Back 129

extends the SQLiteOpenHelper class that provides methods for creating & updating the database (onCreate & onUpgrade)

Front 130

database code structure : Constants class

Back 130

hold all the string constants (table name, column names, etc), that will be used in both Database & MyHelper classes

Front 131

how to read data from SQLite database?

Back 131

query() pass the selection criteria & desired columns

result from the query are returned in a Cursor object

Front 132

what is a Cursor object?

Back 132

it gives us access to the results returned from a database query & allows navigation through the result

*android.database.Cursor

Front 133

select query with condition

Back 133

add new method to retrieve from the database in Database class

Front 134

how do you link database data to the UI?

Back 134

create a new activity & use SimpleCursorAdapter to link

Front 135

what is a SimpleCursorAdaptor?

Back 135

an easy adapter to map columns from a cursor to TextViews/ImageViews defined in XML

Front 136

whats the advantage of using SimpleCursorAdapter?

Back 136

dont need to process the data from the cursor, just need to indicate which columnsare displaying into the UI controls with the ID column

Front 137

what is a process?

Back 137

an executing instance of an application that run in their own memory space

Front 138

what is a thread?

Back 138

threads share the same memory space & several threads can be associated with 1 process

Front 139

Process & threads in Android

Back 139

we can arrange for different components in the app to run in separate processes & create additional threads for any process

Front 140

how to decide which process has higher priority?

Back 140

the process that the user is interacting at that moment have higher priority

Front 141

which process is terminated first?

Back 141

process with lowest importance is terminated first

Front 142

what processes have highest importance with respect to the user?

Back 142

1. foreground processes have the highest priority

2. visible process: activity on onPause & service bound to a visible activity

3. service process: no direct user interaction & service running (eg: playing music)

4. background process: no user interaction at all & the app most recently seen by the user is the last one to be destroyed

5. empty process: no active component running & still alive for caching purposes

Front 143

process ranking

Back 143

-foreground processes have the highest priority

- empty process is terminated first

- a service is ranked higher than a process that does not have a service

* its better to use a service for long-running operations, rather than performing long-running operations in a thread

Front 144

multithreading in Android

Back 144

every process has a main thread

Front 145

what is the role of the main thread?

Back 145

- the UI elements is updated

- clicking a button sends a message

- startService() and service code is processes

Front 146

whats the effect does long running operation have on main thread?

Back 146

the app appears to be frozen whcih the UI thread will be blocked, no events/drawing events can be dispatched while the main thread is trying to process the long running operations

Front 147

what is UI thread?

Back 147

main thread of execution

Front 148

how to avoid blocking the UI/main thread?

Back 148

Front 149

how to improve responsiveness in main thread?

Back 149

avoid performing blocking operations on the UI/main thread

Front 150

what is ANR?

Back 150

when long operation is not responding, "Application Not Responding" dialog appears

Front 151

whats StrictMode in the UI thread?

Back 151

a developer tool which detects things you might be doing by accident (catch accidental disk/network access on main thread) & brings them to attention so you can fix it

Front 152

AsyncTask

Back 152

complete tasks asynchronously & communicate back to the main UI thread

Front 153

whats the purpose of AsyncTask use in main thread?

Back 153

handle events from different Views & components

Front 154

whats the purpose of AsyncTask use in ActivityManager & WindowManager?

Back 154

monitor the application for responsiveness

Front 155

whats the purpose of AsyncTask use in each task?

Back 155

if it takes more than 5 second, the ANR dialog is triggered

Front 156

in what situation should AsyncTask be used?

Back 156

its good for tasks lasting between 100ms to a few seconds, not more than a few second

* for longer tasks: use services

Front 157

whats some limitations of AsyncTask?

Back 157

not suitable for tasks longer than a few seconds, & it will not execute successfully as Android may kill those thread under critical considtions

Front 158

why should we use Asyntask?

Back 158

its easier to implement in comparison to thread & handler

it manage message queues, updating on progress & create/terminate background thread automatically

Front 159

how can we implement AsyncTask?

Back 159

Front 160

whats the steps for implementing AsyncTask & where is it triggered?

Back 160

- onPreExecute() runs on UI thread before background processing begins

- doInBackground(Param...params) runs on a background thread & won't block UI thread

- publishProgress(Progress...values) method invoked by doInBackground triggers call to onProgressUpdate() on UI thread

- onPostExecute(Result result) runs on UI thread once doInBackground is done

Front 161

steps of implementing AsyncTask - methods

Back 161

Front 162

what kind of parameter is provided to AsyncTask?

Back 162

Param: type of parameter sent to the task for exercution

Progress: type of info used to indicate progress

Result: type of the result received from the background task

Front 163

important notes about AsyncTask

Back 163

- AsyncTask class must be loaded on the UI thread

- the task instance must be created on the UI thread

- execute() must be invoked on the UI thread

- onPreExecute, onPostExecute, doInBackground, onProgressUpdate are called automatically, don't call them in code

Front 164

whats services?

Back 164

app component that complete long-running operations in the background & no UI

another app component can start a service & the service will continue to run in the background even if the user switches to another app

another app component can bind to a service & interact with it

Front 165

whats some uses of service?

Back 165

Front 166

whats the types of service?

Back 166

1. started

2. bound

*can also have a started service (to run indefinitely) that allows binding

Front 167

types of service : started

Back 167

- started by an app component startService()

- runs in the background *even if the component that started it is destroyed

- single operation

- does not return a result to a caller

Front 168

types of service : bound

Back 168

- app bind to it: bindService()

- client-server interface: send requests/get result

- runs only as long as a component bound to it?

Front 169

where does the service run?

Back 169

it runs in the main thread of its hosting process

*service does not create its own thread/run in a separate process

Front 170

creating a service

Back 170

Front 171

how is the service created and destroyed?

Back 171

service lifecycle: it can run in the background without the user being aware

Front 172

started service: classes to extend

Back 172

Front 173

whats the steps of creating a service?

Back 173

1. create a class to extend service

2. declare the service in Manifest

3. override the onCreate & onDestroy

4. override the onBind

5. activate the service from an external trigger

Front 174

how is the service behaving?

Back 174

- doesn't stop when the activity is destroyed (change screen orientation)

- doesn't stop when the activity is paused (press the home button)

- runs as its own entity

Front 175

whats a fragment?

Back 175

stand alone parts/block of UI

Front 176

whats the characteristics of fragment?

Back 176

1. small component/portion/chunk of UI

2. has its own lifecycle

3. can process its own events

4. can be added/removed while activity runs

Front 177

why do we use fragments?

Back 177

- combine several fragments in a single activity with flexibility & dynamic UI design

- different layouts for different screen space size portrait/landscape

Front 178

whats the steps for creating fragment?

Back 178

1. create class for fragment (extend Fragment class)

2. provide layout (appearance) for fragment in xml

3. override onCreateView() to link the layout to the Java class from step 1

4. use the fragment in XML (static bound to UI) / java (dynamic - preferred approach)

Front 179

whats the fragment lifecycle?

Back 179

1. fragment as a java object when we first created

2. active that is running & linked to the activity

3. destruction

Front 180

how does fragment lifecycle relate to activity lifecycle : fragment creation?

Back 180

*activity start first, fragment then follows

onAttach: after the fragment is associated with the activity, it get a reference to the activity object

onCreate: do not access UI objects, activity onCreate may not be completed yet

onCreateView: link javs with xml & return view for fragment

onActivityCreated: called after onCreate has completed, ready to access/modify UI elements

Front 181

how does fragment lifecycle relate to activity lifecycle : fragment destruction?

Back 181

* fragment first, activity follow

onSaveInstanceState: used to save info inside a Bundle object

onDestroyView: destroy the view after the fragment view hierarchy is no longer asccesible

onDestroy: fragment is completely destroyed, it is still an object attached to the activity, but not usable

onDetach: fragment is untied from activity

Front 182

how to add fragment to activity?

Back 182

1. XML approach

2. Java approach (preferred)

Front 183

adding fragment approach : XML

Back 183

static association of fragment with activity

* < fragment >

Front 184

adding fragment approach : Java

Back 184

its a dynamic approach & the fragment is added at run-time in response to user interaction using Fragment Manager

Front 185

whats the role of Fragment Manager?

Back 185

it uses getFragmentManager() to maintain references to all fragments inside the activity

*retrieve ID(XML-findFragmentById())

tag(Java-findFragmentByTag())

Front 186

how is transactions processed in fragment?

Back 186

perform changes on several fragments at the same time, where the changes can be included in the same transaction

Front 187

how do you begin a transaction?

Back 187

call the add method on the transaction:

transaction.add(R.id.Myout, frag, "Fragment2");

transaction.commit();

Front 188

Fragment transaction

Back 188

- either process with everything/nothing

- remove fragment (to be removed) first, then bring in new fragment

Front 189

why is communication between fragments needed?

Back 189

user performs some interaction on Fragment , which will lead to some event happening in Fragment 2

Front 190

whats the rules of communication between fragments?

Back 190

do not maintain references of 1 fragment within another fragment, interface is needed

Front 191

interfaces in java

Back 191

it is standardized & contain methods with no body, so no implementation

it cannot create object of an interface but it can declare variable for an interface type

Front 192

whats webview?

Back 192

a view that displays web pages

*basis for creating your own web browser/display online content inside of activity

Front 193

how can webview be used?

Back 193

Front 194

how do you handle URL Requests?

Back 194

provide a WebViewClient for your Webview, using setWebViewClient()

Front 195

what are web services?

Back 195

web services are means of exposing an API over a technology-neutral network endpoint

Front 196

whats JSON?

Back 196

Java Script Object Notation

a way to represent JavaScript objects as Strings & alternative to XML for passing data between servers and clients

Front 197

what data does web service return?

Back 197

XML/JSON strings

Front 198

what does JSON format build on?

Back 198

build on a collection of name-value pairs (objects, records, structs, etc) and an ordered list of values (array)

Front 199

what form can JSON values take in?

Back 199

Front 200

whats the steps of accessing and capturing data from web service?

Back 200

1. check the network connection

2. perform network operation on a separate thread - setup separate thread

3. connect & connect data

4. convert data from network into a target data type

Front 201

how to check the network connection?

Back 201

Front 202

why should network operation be performed on a separate thread?

Back 202

to avoid unpredictable delays that provide poor user experience

Front 203

how do you setup separate thread for network operation?

Back 203

using AsyncTask

Front 204

how do you perform network access?

Front 205

how do you connect and download data from web service?

Back 205

use HTTP to send & receive data

Front 206

whats Apache HttpClient?

Back 206

it requires minimal code for simple HTTP processing that is stable and have very few bugs

*but not recommended

Front 207

whats HttpURLConnection?

Back 207

a lightweight client member of the package java.net that process the requests & responses (other classes from the package java.io)

*perfectly suited for use with web services

Front 208

whats the step and the usage of HttpURLConnection?

Back 208

1. obtain a new HttpURLConnection by calling URL.openConnection() & casting the result to HttpURLConnection

2. prepare the request

3. transmit data by writing to the stream returned by getInputStream()

4. read the response. The response body may be read from the stream returned by getInputStream(). If the response has no body, that method returns an empty stream

5. Disconnect. Once the response body has been read, the HttpURLConnection should be closed by calling disconnect(). Disconnecting releases the resources held by a connection so they may be closed/reused

Front 209

what is Android Touch Framework?

Back 209

shows how android system handles touches

Front 210

whats touch event?

Back 210

touch event starts when user touch the screen with 1/more fingers

Front 211

what kind of information is gathered from touch event?

Back 211

index/points of fingers, coordinate of touch & velocity (x & y)

Front 212

how is event propagated?

Back 212

dispatchTouchEvent()

event flow top down through views

Front 213

how is Android Touch Handling?

Back 213

user touch(motion event) is delivered to onTouchEvent() that provides detail of every user interaction

*ACTION_DOWN: first primary finger

*ACTION_POINTER_DOWN: second/more finger

Front 214

whats a gesture?

Back 214

its defined as beginning with ACTION_DOWN & ending with ACTION_UP

all actions between ACTION_DOWN & ACTION_UP

Front 215

whats one finger gestures?

Back 215

single touch

Front 216

whats 2/more finger gestures?

Back 216

multi touch

Front 217

custom gestures

Back 217

Front 218

how do you use gestures to enable the arrangement of view controls?

Back 218

with drag/drop framework

Front 219

challenges in working with gestures

Back 219

a gesture can be made of multiple touch events/motions

different sequences of motion add up to different gestures where each sequence can trigger motion events that applications can react to

Front 220

detecting user motion/gesture in UI view

Back 220

it can be handled similar to click event

UI classes inheriting from view allow to set listeners that respond to basic gestures & listeners are defined bu suitable interfaces

Front 221

approaches of gestures

Back 221

Front 222

whats MotionEvent object?

Back 222

object created when the user touches the devices touchscreen

Front 223

whats the sequence of MotionEvent?

Back 223

- user touches the touchscreen

- user moves the finger on the screen

- user lifts up the finger

Front 224

what kind of information does MotionEvent object contain?

Back 224

- type of action captured

- pressure value

- x, y coordinates

- time of the event

Front 225

how do you detect gesture?

Back 225

gather data about touch event & interpret the data to find the pattern of any gestures of interest

Front 226

what is drag & drop?

Back 226

it allow users to move data from 1 view to another view i the current layout using graphical drag & drop gesture

Front 227

whats included in drag & drop framework?

Back 227

- drag event class

- drag listeners

- touch listeners

- helper methods & classes

Front 228

whats the use of drag & drop?

Back 228

drag an icon over another icon to obtain certain result

eg: color mix app

Front 229

whats the steps of drag & drop operation?

Back 229

Front 230

how to setup drag event listener?

Back 230

set the drag event listener object for a view with setOnDragListener() that have onDragEvent() callback method

contains an action type that tells the listener what is happening in the drag/drop process

Front 231

the drag & drop process states

Back 231

Front 232

drag & drop process states : Drag Started

Back 232

user makes a gesture to begin to drag, the app calls startDrag() to tell the system to start a drag

a drag shadow is provide

Front 233

drag & drop process states : Drag Continuing

Back 233

user continues the drag & the drag shadow intersects the bounding boxes of view objects

Front 234

drag & drop process states : Dropped

Back 234

user releases the drag shadow within the bounding box of a view that can accept the data

the listener is expected to return true if code for accepting the drop succeeds

Front 235

drag & drop process states : Drag Ended

Back 235

happens after the user releases the drag shadow where the event is sent to every registered listener

Front 236

whats drag shadow?

Back 236

during drag & drop operation, the system displays a shadow that the user drags indicating the data is being dragged

Front 237

what size should the drag shadow be?

Back 237

it should be small to improve performance

Front 238

whats the steps of designing a drag & drop operation?

Back 238

1. start a drag

2. respond to events during the drag

3. respond to drop event

4. end the drag & drop operation

5. responding to a drag end

Front 239

designing a drag & drop operation : starting a drag

Back 239

user starts drag with drag gesture (long press/touch)

- the data should be saved with ClipData

- define DragShadowBuilder to create a shadoe for dragging

Front 240

how to allow a view to be dragged?

Back 240

register OnTouchListener/LongClickListener on views

specify the data which is passed to the drop target using ClipDate

Front 241

designing a drag & drop operation : responding to a drag start

Back 241

during the drag operation, the system dispatches drag event to the drag event listener of the view objects in the current layout, & the listeners should react by calling getAction(0 to get station type

Front 242

designing a drag & drop operation : handling events during the drag

Back 242

during the drag, listeners that returned true in response to the ACTION_DRAG_STARTED drag event continue to receive drag events (location of the drag shadow & visibility of the listener's view)

Front 243

designing a drag & drop operation : responding to a drop

Back 243

the user releases the drag shadow on a view in the app where the system dispatches a drag event with ACTION_DROP action type

Front 244

drop target

Back 244

the views which can be drop targets get an instance of OnDragListener assigned

Front 245

designing a drag & drop operation : responding to a drag end

Back 245

immediately after the user releases the drag shadow, the system sends a drag event to all of the drag event listeners in the activity, with ab action type of ACTION_DRAG_ENDED

Front 246

whats Google Maps API?

Back 246

its a free component of the Google Play services library

Front 247

what can we do with Google Maps?

Back 247

Front 248

how do we add Google Map into an app?

Back 248

1. add permissions in manifest (internet, access_network_state, write external_storage, read_services from google)

2. register the app & get a personal API key with Google account

3. place the API key in the manifest file

4. check Google services APK (if (servicesOk))

Front 249

how can we display a map?

Back 249

1. create a new layout file using map fragment

2. use setContentView(R.layout.activity_map); in Java

Front 250

how can we manipulate the map?

Back 250

1. get a reference to the map object

2. use a method to check if the map has been initialized successfully

Front 251

whats the initial state of the map?

Back 251

its always centered in the same location at the intersection of Equator (double 0.0 latitude)& Prime Meridian (double 0.0 longitude)

Front 252

how do we start a map from a customized location?

Back 252

retrieve lat & lng of the locatin add inn XML/Java

Front 253

change location in XML

Back 253

can change map type with map:mapType (satellite, hybrid)

Front 254

change location in Java

Back 254

add constants for the lat & lng

Front 255

add zoom to location

Back 255

Front 256

whats Geocoding?

Back 256

a process of converting address into geographic coordinate for adding place markers/position

Front 257

what does Geocoder class do?

Back 257

it wraps up all request & response functionality, returns everything back to as a Java object using getFromLocation & getFromLocationName

Front 258

geolocate(View v)

Back 258

Front 259

how can you find the device's current location?

Back 259

current location is found based on proximity to cell phone towers & wireless networks (coarse_location) & based on GPS (fine_location)

Front 260

what permission do we need in manifest to get current location?

Back 260

Front 261

how do you get current location using non-code approach?

Back 261

Front 262

how do you get current location using in-code Java approach?

Back 262

Front 263

whats map markers?

Back 263

it adds markers to a map

Front 264

what can you do with map markers?

Back 264

- adding & removing map markers

- customizing marker icon graphics

- handling marker events

- dragging & dropping markers

Front 265

how do you add a marker?

Back 265

Front 266

how do you remove map markers?

Back 266

map markers are removed when the activity is destroyed

Front 267

how do you customize marker icon?

Back 267