TrackMySleepQuality

Room - SleepQualityTracker app

This is the toy app for Lesson 6 of the Android App Development in Kotlin course on Udacity.

SleepQualityTracker

The SleepQualityTracker app is a demo app that helps you collect information about your sleep.

• Start time
• End time
• Quality
• Time slept

This app demonstrates the following views and techniques:

• Room database
• DAO
• Coroutines

It also uses and builds on the following techniques from previous lessons:

• Transformation map
• Data Binding in XML files
• ViewModel Factory
• Using Backing Properties to protect MutableLiveData
• Observable state LiveData variables to trigger navigation

Screenshots

Tc2r1's Notes:

• Scheduler handles priorities and makes sure all threads finish.
• Dispatcher sets up threads
• Main thread runs in the foreground, and can dispatch other threads.
• Main thread handles all updates to the UI and calls all click handlers and other UI and lifecycle callbacks.
• If you block the Main thread for too long, it will stutter or even freeze, it can crash with ApplicationNotResponding.

COROUTINES

Coroutines handle long running task elegantly and efficiently.

Coroutines can signal errors with exceptions.

Coroutines are Asynchronous

• The coroutine runs independently from the main execution steps of the program.

Coroutines are Non-blocking

• The system is not blocking the main or UI thread.

Coroutines are Sequential

• Suspend allows other work to happen while waiting for response

JOB

• A background job. Conceptually a job is a cancellable thing with a life-cycle that culminates in its completion.
• Jobs can be arranged in a parent child hierarchy, so that cancelling a parent cancels the child coroutines.

Dispatcher

• Sends off coroutines to run on various threads.

Scope

• The scope combines information, including a job and dispatcher, to define the context in which the coroutine runs.
• Scopes keep track of coroutines.

In fragment first reference application = this.activity.application

Arguements = FragmentArgs.fromBundle(arguements)

dataSource = database.getInstance(application).dao

Factory = Factory(safeargs)

VieModal = ViewModelProvider(owner, factory)[class]

Tc2r1's RECAP

• Used a Room Database to store retrieve and update my data.
• Created a sleepNights data class to define a database table and it's structure.
• Made a Data Access Object to define the API for our database, creating mappings between kotlin functions and SQLite queries.
• I made a room database singleton.
• ViewModelFactory for dependency injection.
• Added ViewModels to manage database operations and handle user clicks.
• Used Coroutines to make sure the database operations don't interfere with a smooth user experience.
• Implemented Observable state variables to keep UI operations, such as navigation in the fragment.