Iat 381 Quiz 3

Front 1

what are the 5 persistent data storage options in android?

Back 1

- SharedPreferences (key value pairs)

- Interal Storage (device memory)

- External Storage (shared external storage)

- SQLite Database (structured, private data)

- Network Connection (on web, with network server)

Front 2

what are SharedPreferences? what's an example of data that'd be put in?

Back 2

primitive data stored as key/value pairs

private to the app

e.g. username and password

key = username

value = "runnerDave"

Front 3

what is internal storage? is it public or private to the app?

Back 3

save files directly on the device's internal storage

private files to the app

if app is uninstalled, files are removed

Front 4

what happens if app is uninstalled with data that's private?

Back 4

all the data will go away

Front 5

what's external storage? what's an example? is it public or private?

Back 5

removable storage media

non-removable internal storage

readable by anyone -> public

e.g. SD card

Front 6

in the SQLite database, what kind of data would you store? is it public or private?

Back 6

complex and structured data

private to app

e.g. it's a table storing activity ID, type, distance, time, calories

Front 7

what file is SharedPreferences stored in?

Back 7

XML file (data/data//shared-prefs)

Front 8

what is the kind of data that you store in SharedPreferences? and what are examples?

Back 8

PRIMITIVE DATA: boolean long int float string

user info, location, when app was last updated, settings, if user is using app for first time

Front 9

how to access preferences in code? 2 ways

Back 9

getPreferences(int mode)

- just one shared preferences file

or getSharedPreferences(String name, int mode)

- means multiple preferences files saved, so you specify the name

Front 10

what are the 4 steps to store data in SharedPreferences?

Back 10

1. get references to SharedPreferences object

- getPreferences() or getSharedPreferences()

2. call the Editor edit()

3. use editor to add data with a key (e.g. putBoolean, putString)

4. commit editor changes commit()

Front 11

what is SQLite?

Back 11

language for managing data in relational databases

Front 12

what class and method allows us to create the SQLite database? what about performing changes?

Back 12

SQLiteOpenHelper

onCreate -> creates database

onUpgrade -> perform changes to database

Front 13

how do you get the SQLite database object? it's a method

Back 13

getWritableDatabase()

Front 14

what are the 3 steps in creating SQLite database schema?

Back 14

1. define schema

- database name, version, table names, column names

2. create database

- queries to create the database

3. execute queries

- insert, update, delete operations

Front 15

when is onCreate() called? what does it do?

Back 15

called when database is first created

creation of tables

initial data inside of table

Front 16

when is onUpgrade() called? what does it do?

Back 16

called whenever the database is updated

can drop, add tables, delete table, anything that updates the database structure/schema

Front 17

each time you do a change in the database, WHAT do you have to change for it to update?

Back 17

THE VERSION

Front 18

what is the SQLiteDatabase class?

Back 18

An object representing the database that was created

Front 19

what does public void execSQL(String sql) do? what's an example?

Back 19

executes a single SQL statement

e.g. db.execSQL(CREATE_TABLE)

Front 20

what is the condition for the database to get created? what's the line of code?

Back 20

only when there is an attempt to access it for the first time

call the method getWritableDatabase()

Front 21

how to insert new row in database? what query is it and how do you do it

Back 21

insert query

1. create an object of class ContentValues

2. contentValues.put(Constants.NAME, name);

(key, value)

3. long id = db.insert(Constants.TABLE_NAME, null, contentValues);

Front 22

what does nullColumnHack do?

Back 22

lets you insert a row that's empty

Front 23

what 3 classes should you separate your database code into?

Back 23

MyDatabase class

- contains SQLite Database instance and helper

MyHelper class

- extends SQLiteOpenHelper class and contains onCreate() and onUpgrade()

Constants class

- holds String constants like table names

Front 24

how to read data from database? what's the method? what does that method return?

Back 24

query() - returns a Cursor object with the results of the query

Front 25

what does SimpleCursorAdapter do?

Back 25

for ListView: maps columns from a cursor to TextViews or imageViews defined in an XML file

Front 26

diff between process and thread in terms of memory space

what can one process be associated with?

Back 26

process

- run in their OWN memory space

thread

- share same memory space

one process can be associated with several threads

Front 27

what is a process?

Back 27

executing instance of an application

Front 28

what is the default 3 steps of processes and threads in android starts?

Back 28

1. application component starts FIRST TIME

- no other component is running

2. android starts NEW PROCESS in a single thread of execution

3. another component of the app starts, and it runs in same process and same thread

Front 29

before terminating a process, what does android do? what will be terminated last?

Back 29

assess its importance/priority in reference to the user

the processes with which the user is interacting at that moment have higher priority

Front 30

what are foreground processes?

Back 30

processes that have current user interaction

Front 31

what is the ranking of process termination?

Back 31

1. foreground

2. visible processes

3. service process

4. background process

5. empty process

Front 32

what are examples of activity, service, and braodcast receiver in its highest priority/foreground?

Back 32

activity

- when onResume()

service

- when the service is BOUND to the current activity

- when there's user interaction

broadcast receiver

- while executing onReceive() method

Front 33

what does visible processes mean? how do we define it? give an example in terms of activity and service

Back 33

when the activity is onPause(), the user can still SEE it

or service is bound to a visible activity

Front 34

what is a background process defined as? how to determine last to be destroyed?

Back 34

no user interaction at all

the app most recently seen by the user is the last one to be destroyed

Front 35

what does empty process mean? why is it still running?

Back 35

no active component running

still alive for caching purposes

Front 36

what is a service process? how is it ranked?

Back 36

process running a service

ranked higher than a process that does not have a service

Front 37

if you have a long-running operation, what should you use rather than an async thread? and why?

Back 37

use a SERVICE (it can only go low as 3)

if you use an async thread, it's still in the same process so it might become background (and can get ranked 4)

Front 38

what is a long-running operation? give some examples

Back 38

everything that exceeds a few seconds

everything that goes out of the application sandbox

- working with files

- network access

- database access

- complex calculations

Front 39

why don't you want to put long-running operations in the main thread?

Back 39

blocks the UI so main thread will be busy processing long-running operations so other things in the queue will be delayed

Front 40

what do you need to keep in the main thread?

Back 40

UI

Front 41

3 ways to enable responsiveness

Back 41

AsyncTask helper class - recommended

- complete tasks asynchronously and communicate back to the main UI thread

Java Thread class

Loader class

- facilitate the loading of data for use in activity or fragment while still starting up quickly

Front 42

async task is good for tasks lasting how long?

Back 42

100ms to a few seconds

Front 43

2 reasons to use AsyncTask as opposed to java approaches?

Back 43

1. easier to implement in comparison to thread and handler

2. automates:

- creation termination of background thread

- managing of message queues

- updating on progress

Front 44

what are the 2 steps of implementing AsyncTask? what can overriding its methods do? 3 things

Back 44

1. create subclass of AsyncTask

2. override one or more AsyncTask methods to:

- do work inside bg thread

- handle UI updates in main thread

- when needed, create instance and call execute() to have it begin doing its work

Front 45

what are the methods in order of the steps for AsyncTask? what do these methods do?

Back 45

execute()

onPreExecute()

- callback

- maybe make a progress bar

------ task running

doInBackground()

- where the actual work happens (e.g. network calls)

- called in bg thread

publishProgress()

- we can send value about the progress

- called in bg thread

onProgressUpdate()

- triggered from publishProgress

- update UI elements

----- task finished

onPostExecute()

- called on main thread after result is returned

- clean up work e.g. we don't need progress bar so hide it

Front 46

what are the 3 parameters you can send with AsyncTask methods?

Back 46

Param

Progress

Result

Front 47

what are the callback methods in AsyncThread? what do you have to call?

Back 47

onPreExecute()

doInBackground()

onProgressUpdate()

onPostExecute()

execute() and publishProgress()

Front 48

what are the 2 types of services?

Back 48

started

bound

Front 49

what is a started service? what's it started by? is it single operation? what does it return? who stops it?

Back 49

runs in bg even if the component that started it is destroyed!!

started by startService()

single operation

doesn't return result to caller

you can stop itself or have the activity stopService() it

Front 50

what is a bound service? when does it run? what do you call to use it?

Back 50

bindService()

there's an app bound to it

runs only as long as a component is bound to it

Front 51

can you have a started service to run indefinitely that allows binding?

Back 51

yes

Front 52

where does the service run? (e.g. which thread and process)

Back 52

runs in MAIN THREAD and doesn't run in a separate process

Front 53

what is the service lifecycle (4 methods)

Back 53

onCreate()

onStartCommand()

onBind() -> if service allows binding

onDestroy()

Front 54

what is the started service lifecycle? what happens if the service is stopped?

Back 54

1. startService() started by another component

2. onCreate()

3. onStartCommand()

4. stopSelf() or stopService()

5. onDestroy()

when service stopped, system DESTROYS it

Front 55

what is the bound service lifecycle? how does it get stopped/destroyed?

Back 55

1. bindService() - another component (client) calls

2. onCreate()

3. onStartCommand()

4. unbindService() - client can close connection

5. onDestroy()

multiple clients can bind to same service when all of the unbind, system destroys the service

Front 56

what does it mean that the service has a lifecycle independent of the component that started it?

Back 56

it means if the component is destroyed, the service isn't destroyed

Front 57

what is the base class for all services and what does it do?

Back 57

Service class

creates new thread to perform the service's intensive work

Front 58

what is IntentService class?

Back 58

subclass of service class

worker thread to handle all starter requests

Front 59

should you create a new thread inside your service?

Back 59

depends - if it's a large bg job then yes (e.g. playing music from the web)

Front 60

what does cursor object give us access to, and what does it allow?

Back 60

the results returned from a database query

allows navigation through the result set

Front 61

what is the main method of the intent service class? what does it do?

Back 61

onHandleIntent()

receives intent for each start request

Front 62

what is the param parameter in AsyncTask?

Back 62

type of parameter sent to task for execution

Front 63

what is the progress parameter in AsyncTask?

Back 63

type of info used to indicate progress

Front 64

what is the result parameter in AsyncTask?

Back 64

type of result received from bg task