Get All Weeks Android App Components – Services, Local IPC, and Content Providers Quiz Answers

This 4 week MOOC builds upon the core Android app components and concurrency frameworks covered in Course 2 by focusing on started and bound services, local inter-process communication (IPC), and content providers. Case study apps will be examined from multiple perspectives to learn how to program these app components using Android’s material design paradigm.

Students will work incrementally on a hands-on project involving a material design-based RSS reader app. Each week you will add additional capabilities to the project, based on material covered in the lecture videos. You’ll spend roughly 4 hours per week watching video lectures, taking quizzes, and programming assignments with Java and Android.

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Week 1: Android App Components – Services, Local IPC, and Content Providers Quiz Answers

Quiz 1: Module 1 – Overview of the Android App Components

Q1. Which of the following are ways in which the

Layers pattern structures software apps and infrastructure

(choose all that apply):

• Provides services beyond
  
  the operating system and protocol stacks to enable components in a distributed system to communicate and manage data
• Decomposes groups of subtasks into levels of
  
  abstraction
• Enables end-to-end communication by specifying
  
  how data should be (un)packetized, addressed, transmitted, routed, and received
• Partitions an overall system architecture into
  
  groups of subtasks

Q2. Which of the following are reasons that layering

is applied in Android (choose all that apply):

• Reduces the complexity of APIs that app
  
  developers must understand
• Enables “plug and play” replacement of
  
  certain layer implementations
• Enhances systematic software reuse
• Increases context switching, synchronization,
  
  and data copying overhead

Q3. Which of the following are implications of

being “higher” in the memory

hierarchy of a modern computing device (choose all that apply):

• CPU access latency is higher
• Cost is greater
• Memory bandwidth is slower
• CPU access latency is lower

Q4. Which of the following are correct statements of

Android linux RAM (choose all that apply):

• Apps running in user space can never access RAM
  
  of other apps
• All Android apps execute in user space RAM
• Android Linux executes in kernel space RAM
• User space is a less restrictive protection
  
  domain than kernel space

Q5. Which of the following are true statements

about Android’s local and remote

inter-process communication (IPC) mechanisms (choose all that apply):

• These IPC mechanisms reside within the kernel’s
  
  device driver framework
• UNIX domain sockets are used to communicate
  
  with remote UNIX servers
• The Binder driver supports highly optimized LAN
  
  and WAN communication
• TCP/IP is used to access the Internet

Q6. Which of the following are true statements about

processes in Linux (choose all that apply):

• Processes appear at multiple layers in the
  
  Android software stack
• A process contains one thread by default
• A process provides units of execution for
  
  instruction streams that run on processor cores
• A process provides a unit of resource allocation
  
  and protection

Q7. Which of the following are true statements

about the Android Hardware Abstraction Layer (HAL) (choose all that apply):

• Android apps rarely access the HAL directly
• It is implemented in kernel space to optimize
  
  performance and is written largely in C
• It is implemented in user space and is written
  
  largely in Java
• It shields higher layers of Android’s software
  
  stack from Linux kernel idiosyncracies
• It’s open source license ensures that all HAL
  
  driver implementations are available in open-source form
• It is implemented in user space and is written
  
  largely in C/C++

Q8. Which of the following are true statements

about the the “Android Runtime” (ART) execution

environment that are not true for the Dalvik VM execution environment (choose all that

apply):

• It provides an “Ahead-of-Time” (AOT)
  
  compiler
• It provides a better garbage collector
• It provides a Just-in-Time (JiT) compiler
• It executes standard Java Bytecode

Q9. Which of the following are examples of app

components available in Android core libraries (choose all that apply):

• Stamped Locks
• Activity
• Service
• Threads
• Phasers
• Content Provider

Q10. Which of the following are benefits of the

Android Native Development Kit (NDK) (choose all that apply):

• It provides a managed runtime environment for
  
  executing Java garbage collection efficiently
• It can help enhance performance by minimizing
  
  latency and maximizing throughput
• It can help integrate existing C/C++ libraries
  
  into Android apps
• It can help improve portability across
  
  heterogeneous Java platforms

Week 2: Android App Components – Services, Local IPC, and Content Providers Quiz Answers

Quiz 1: Module 2 – Started and Bound Services

Q1. Which of the following are ways in which

activities in Android are designed

to be “ephemeral” (choose all that apply):

• They perform long-duration operations and/or
  
  access remote resources via background
  
  threads/processes
• They are destroyed and recreated to handle
  
  runtime configuration changes
• They are destroyed (and must be recreated later)
  
  when the back button is pressed
• They can interact with the user in powerful
  
  ways

Q2. Which of the following are types of Android

services (choose all that apply):

• Background services
• Bound services
• Scheduled services
• Started services

Q3. Which of the following are examples of Android

“hybrid” services (choose all that apply):

• Activity Manager Service
• DownloaderService
• Alert service
• MusicPlaybackService

Q4. Which of the following lifecycle hook methods

apply to started services (choose all that apply):

• onRebind()
• onBind()
• onDestroy()
• onCreate()
• onStartCommand()
• onUnbind()

Q5. Which of the following service lifecycle hook

methods can be dispatched by Android when a bound service is

in the “running” state (choose

all that apply):

• onUnbind()
• onBind()
• onCreate()
• onDestroy()

Q6. Which of the following are examples of

differences between the onCreate() and onStartCommand() hook methods of

a started service (choose all that apply):

• onStartCommand() is called once when
  
  startService() is first called, whereas onCreate() is called each time
  
  startService() is called
• onCreate() is called once when startService()
  
  is first called, whereas onStartCommand() is called each
  
  time startService() is called.
• onStartCommand() receives the intent passed by
  
  the client that calls start service, whereas onCreate() does not
• onCreate() receives the intent passed by the
  
  client that calls start service, whereas onStartCommand()
  
  does not

Q7. Which of the following are correct statements

about the types of intents that can be used to create activities

and services (choose all that apply):

• An activity can be created via an explicit
  
  intent
• An activity can be created via an implicit
  
  intent
• A service can be created via an implicit intent
• A service can be created via an explicit
  
  intent

Q8. Which of the following are reasons why the

MusicPlayer app is a simple example of a started service (choose all

that apply):

• It doesn’t need to spawn any internal threads
  
  explicitly
• There’s no communication from the service back
  
  to the activity that invoked it
• It is not started on-demand via the Activity
  
  pattern
• It runs the service in the same process as the
  
  activity

Q9. Which of the following are benefits of the

IntentService framework (choose all that apply):

• It optimizes the scalability of concurrent
  
  services on multi-core hardware platforms
• It simplifies the creation of services that
  
  process requests concurrently
• It enables subclasses of IntentService to
  
  interact with the user in sophisticated ways
• It doesn’t require the complexity of the
  
  Model-View-Presenter pattern to handle runtime
  
  reconfiguration changes

Q10. Which of the following explain the role of a

deployment model in Android (choose all that apply):

• It makes it easy to run a service in the same
  
  thread or different threads
• It makes it easy to run a service in the same
  
  process or different processes
• It directs the physical deployment of services
  
  to threads
• It directs the physical deployment of services
  
  to processes

Week 3: Android App Components – Services, Local IPC, and Content Providers Quiz Answers

Quiz 1: Module 3 – Android: Local Inter-Process Communication (IPC)

Q1. Which of the following are limitations with

using startService() to communicate between an activity and a service

(choose all that apply):

• startService() does not allow extras to be
  
  passed with an intent in a consistent and useful manner
• startService() doesn’t allow an extended
  
  “conversations”
• startService() does not work across process
  
  boundaries
• startService() incurs security and performance
  
  drawbacks

Q2. Which of the following are are unusual or

disallowed use cases for activity and service communication (choose all

that apply):

• Using a broadcast receiver to communicate from
  
  an activity to a started service
• Using a messenger to communicate from a service
  
  to an activity
• Using startService() to communicate from a
  
  service to an activity
• Using a messenger to communicate from an
  
  activity to a started service

Q3. Which of the following are limitations with

using bindService() to communicate between an activity and a service

(choose all that apply):

• bindService() doesn’t allow an extended
  
  “conversations”
• bindService() incurs security and performance
  
  drawbacks
• bindService() does not work across process
  
  boundaries
• bindService() does not allow extras to be
  
  passed with an intent in a consistent and useful manner

Q4. Which of the following are correct statements

about an Android handler (choose all that apply):

• A handler implements the parcelable interface
• A handler can only run in the main thread of
  
  control in a process
• A handler can be used to send and process
  
  messages in one or more threads within a single process
• A handler often eliminates the need for apps to
  
  use synchronizers
• A handler can be used to send and process
  
  messages in one or more threads running in different processes
• A handler reference can be passed as data in a
  
  message or as an extra in an intent

Q5. Which of the following are correct statements

about an Android messenger (choose all that apply):

• A messenger reference can be passed as data in
  
  a message or as an extra in an intent
• A messenger implements the parcelable interface
• A messenger can be used to send and process
  
  messages in one or more threads within a single process
• A messenger can be used to send and process
  
  messages in one or more threads running in different processes

Q6. Which of the following are typical examples of

what a started service does after it receives an intent from

an activity (choose all that apply):

• It enhances in an extended conversation with the
  
  activity
• It performs some processing
• It returns results back to the activity via the
  
  messenger reference
• It returns a Binder reference to the activity
  
  via its onBind() hook method
• It obtains a reference to a messenger from the
  
  intent
• It launches the service using the activator
  
  pattern

Q7. Which of the following are correct statements

about usage considerations for messengers (choose all that

apply):

• Messengers are best suited for simple
  
  interactions and data types
• Messengers shield app developers from
  
  marshaling and demarshaling details of message content
• Messengers are best suited for sophisticated
  
  interactions and complex data types
• App developers are responsible for marshaling
  
  and demarshaling of message content

Q8. Which of the following is the behavior of the

Android Activity Manager Service when the onStartCommand() hook

method returns START_REDELIVER_INTENT (choose all that apply):

• It automatically restarts a killed service via
  
  a new call to onStartCommand() and supplies a null intent
• It does not automatically restart the killed
  
  service, which must be explicitly restarted by an app
• It communicates this return value back to the
  
  client activity
• It automatically restarts a killed service via
  
  a new call to onStartCommand() and supplies the same intent as was
  
  delivered this time

Q9. Which of the following methods must be called

to implement the Android “Concurrent Service Stopping”

idiom (choose all that apply):

• onBind()
• stopSelf()
• onUnbind()
• onStartCommand()

Q10. Which of the following are correct statements

about a bound service (choose all that apply):

• A bound service runs in the background
  
  indefinitely until the mobile device is powered down
• A bound service lives only while it serves other
  
  app components
• A bound service should be used when a client
  
  component wants to have an extended conversation with the service
• A bound service typically does not return a
  
  result to the activity that bound to it

Week 4: Android App Components – Services, Local IPC, and Content Providers Quiz Answers

Quiz 1: Module 4 – Android Content Providers

Q1. Which of the following are reasons why Android

provides a content resolver class (choose all that apply):

• It stores data persistently in an SQLite
  
  database
• It provides additional services, such as change
  
  notification
• It enables a content provider to be shared by
  
  multiple apps
• It defines a schema that represents a resource
  
  managed by a content provider

Q2. Which of the following are operations supported

on content resolvers (choose all that apply):

• insert()
• bulkInsert()
• bulkDelete()
• read()

Q3. Which of the following are actual behaviors of

XML attributes that can be used to define a provider

declaration in an AndroidManifest.xml file (choose all that apply):

• Grant permissions to allow other apps to read or
  
  write to the provider
• List configuration changes that the provider
  
  will handle itself
• Designate if the content provider runs in a
  
  separate process or not
• Indicate the task that the provider has an
  
  affinity for

Q4. Which of the following are terms that appear in

the acronym “ACID” (choose all that apply):

• Implicit
• Concurrent
• Isolated
• Atomic
• Durable
• Consistent
• Asynchronous
• Database

Q5. Which of the following are reasons why Android

apps typically use concurrency

or asynchrony when accessing an SQLite database (choose all that apply)

• SQLite supports the SQL92 specification, which
  
  is obsolete
• SQLite doesn’t support synchronous operations
• Filesystem accesses are often relatively slow
• Android filesystems are unreliable due to their
  
  use of flash memory

Q6. Which of the following are reasons why the

SQLite query() method returns

a Cursor (choose all that apply):

• It alleviates the need to explicitly call
  
  close() on the Cursor
• It is efficient since all data needn’t be loaded
  
  into memory
• It allows buffering of query results
• It ensures that query results work properly in
  
  concurrent programs

Q7. Which of the following are reasons for using a

content provider in an app (choose all that apply):

• To offer complex data to other apps
• To support user-facing operations in different
  
  configuration orientations
• To enable long-duration operations to execute
  
  in the background
• To notify activities automatically when data
  
  changes
• To synchronize local data with remote data
• To launch components on-demand in response to
  
  intents from other components

Q8. Which of the following are parts of a content

URI (choose all that apply):

• An optional part that points to an individual
  
  row in a table
• Metadata defining the synchronization policy
  
  for concurrent access
• A name that points to a table or file
• The symbolic name of the provider

Q9. Which of the following are motivations for

content resolvers supporting

content observers (choose all that apply):

• To initialize the associated content provider
  
  when it’s first created
• To designate rows and columns to return via a
  
  cursor
• To map content URI patterns to integer values
  
  using wildcard characters
• To avoid requiring apps from having to poll for
  
  updates to data storage

Q10. Which of the following are correct statements

about why the HobbitActivity

defines the HobbitOps class (choose all that apply):

• To create and manage the SQLite database
• To manage the persistent storage of Hobbit
  
  characters
• To define the metadata and schema for the
  
  SQLite database
• To consolidate and simplify operations on the
  
  HobbitContentProvider

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