Lecture 2: Major Components of Android Apps

Question 1

What are the 3 major categories that the content of an APK package can be split into?

Answer 1

• Code: .dex files, .so files
• Resources: images, fonts, resource list, etc
• Other files: app manifest, metadata

Question 2

What are the 4 classes of components of an android application?

Answer 2

• Activities: UI and human-computer interfacing
• Services: Background app processes
• Broadcast Receivers: System notifications
• Content Providers: Reading and writing data

Question 3

Can a app only have a single activitity or multiple activities?

Answer 3

Multiple activities withi their own GUI layout, inputs, and outputs

Question 4

True or false?
Activites owned by an app can only be called within that app

Answer 4

False

Activities owned by an app may be called from other applications as well

Question 5

Besides handling UI layout and sharing of application functionality, Activities also server __?

Answer 5

Store user state

Question 6

What is the purpose of the services component?

Answer 6

To handle the background functionality of applications

Question 7

Services do not provide UI but allow __

Answer 7

code to be executed without interrupting other activities

Question 8

What are the different priority levels for a service?

Answer 8

Services the user is aware of:
- Higher priority

Services the user isn’t aware of:
- Lower priority
- Can be put off

Question 9

Like activites services may also be called by ___, this becomes known as a ___ service

Answer 9

• other applications
• bound service

Question 10

What do bound services allow android to do?

Answer 10

Ensure a service stays running as long as the calling app is also running

Question 11

What is the purpose of the broadcast receiver?

Answer 11

To allow an application to receive data and ‘wake up’ without the need for a constantly running background service listener

Question 12

What types of components work in the background and have no UI element or screen

Answer 12

• Services
• Broadcast Receivers

Question 13

Which component can generate system notifications or tell applications to generate system notifications?

Answer 13

Broadcast Receivers

Question 14

What components is more preferable to use over a service and why?

Answer 14

Broadcast Receivers

They have less overhead in terms of resources used

Question 15

What is the purpose of the content provider?

Answer 15

Handle programmatic data access by other applications.

Gives you a way to share data between apps in a controlled and secure manner

Question 16

Content providers let you define ___ data is available and __ it is available

Answer 16

• What
• How

Question 17

What component offeres access to data in some underlying medium using a URI based system?

Answer 17

Content provider

Question 18

A content provider is not to manager your own app’s access to the data but instead to provide __

Answer 18

A managed API for all other apps to access your app data

Question 19

Any component of an app is callable by other applications however __

Answer 19

An application has control over what may be called by other apps

Question 20

Any component of an app is callable by other applications however __

Answer 20

An application has control over what may be called by other apps

Question 21

What is the purpose of the app manifest file?

Answer 21

Tells android:
- Which components make up an app
- Sharing permission of its components
- Overall hardware/software permissions required for the app

Question 22

What type of file is the app manifest and where is it stored?

Answer 22

XML file

The root of the app