Unit 3 Quizzies

  1. Choose an app on your phone. Explain how it might use any one of these features:

    • Singleton objects

    • Interfaces

    • Generics

    • Extension properties

    • Extension functions

    • LazyColumn

    example

    Grab offers various types of rides like GrabCar, GrabTaxi, etc. An interface might be used to define the common functionality of different types of rides. The interface could contain methods like calculateFare(), getDriverLocation(), etc. Each type of ride can implement this interface in its own way.

    #solulu

    • Singleton objects: a media player could use a singleton object that’s responsible for playing audio. This ensures that only one song/video is playing at a time.

    • Interfaces: an interface for an in-app game could include common functions that need to be implemented, like setGameScore(), etc. Example: https://github.com/elbekD/kt-telegram-bot/blob/4a749ffc7f10b2e0a5d3a313c7f7df904ba14892/library/src/main/kotlin/com/elbekd/bot/api/TelegramGameApi.kt

    • Generics: Instagram can show both videos and images, it could use a generic List<T> to work with both types

    • Extension properties: a weather app could use an extension property to convert temperature from Celsius to Fahrenheit

    • Extension functions: a messaging app could use an extension function to format a message before sending it

    • LazyColumn: anything that scrolls, like Instagram, TikTok, reddit could all use a LazyColumn to display items only on demand

  2. LazyColumn tries to optimize performance by loading items on-demand. What are other similar methods that apps on your phone use to achieve the same effect?

    #solulu

    • Pagination: loads items one page at a time

    • Infinite scroll: loads items as the user scrolls

    • Map loading: show the details like roads, buildings, etc. only when the user zooms in

    • Image galleries: load a low-resolution thumbnail first, then load the full-resolution image when the user taps on it

    • Chat history: load old messages from a year ago only if user taps on that specific date

  3. What is one specific example of an ick you have with a animations in a mobile app, and how would you improve it?

    #solulu

    • Progress bars that are stuck at 90+% feel scammy. Either compute the progress more accurately, or show a different animation that doesn’t imply completion.