Android

Question 1

What is an Activity?

Answer 1

An activity is a single, focused thing that the user can do. Almost all activities interact with the user.

https://developer.android.com/reference/android/app/Activity

Question 2

What is a View?

Answer 2

View
- Basic building block of UI
- Drawing and event handling
- Many specialized classes available
Example Views: Button, CheckBox, Spinner, Switch (slider), Plain Text, Multiline Text

Question 3

What is a ViewGroup?

Answer 3

A ViewGroup is a special View that holds other views

Question 4

What is a Layout?

Answer 4

Layout
- Special invisible ViewGroup
- Handles View positioning behavior
- Many specialized classes available
Example Layouts: ConstraintLayout, FrameLayout, ScrollView, LinearLayout, RelativeLayout

Question 5

What Activity class method is typically used in the activity’s onCreate() method to create a window in which you can place the UI?

Answer 5

Overloaded Method: setContentView()
  void setContentView(int layoutResourceId);
  void setContentView(View view);
  void setContentView(View view, ViewGroup.LayoutParams params);

Question 6

What Activity class method retrieves widgets in a UI?

Answer 6

findViewById(@IdRes int id)

Question 7

How are the application resources organized?

Answer 7

Using the auto-generated “R” class with nested classes for types of resources (such as “layout” and “id”).

Question 8

What is an Adapter?

Answer 8

A class that manages the interactions between a View and its data

Question 9

What is an Intent?

Answer 9

A messaging object you can use to request an action from another app component.

https://developer.android.com/reference/android/content/Intent

Question 10

What are the characteristics of an implicit intent?

Answer 10

Implicit Intent Characteristics:

• Action: Specifies the requested action
• Data: Specifies data associated with the action
• Mime Type: Specifies the type of data associated with the action

Question 11

What are the lifetimes within an Activity lifecycle?

Answer 11

Lifetimes within Activity lifecycle

• onCreate() (start total lifetime)
  
  • onStart() (start visible lifetime)
    
    • onResume() (start foreground lifetime)
    • onPause() (end foreground lifetime)
  • onStop() (end visible lifetime)
• onDestroy() (end total lifetime)
• onRestart() (restart visible lifetime)
  
  • called after onStop() and before onStart()

Question 12

What are the three fundamental use cases for intents?

Answer 12

Three fundamental use cases:

• Starting an activity
• Starting a service
• Delivering a broadcast

Question 13

How do you set the Data and Mime Type characteristics of an implicit intent?

Answer 13

• Intent.setData() to set the Data (also clears the Mime Type)
• Intent.setType() to set the Mime Type (also clears the Data)
• Intent.setDataAndType() to set both

Question 14

What does APK stand for?

Answer 14

Android PacKage file