data binding
TRANSCRIPT
Data Binding
TodayfindViewByIdCoordinates between the model and the views
Create untestable codeAnd more...
What is Data Binding?Model View ViewModel (MVVM)
Ongoing link between an element in the user interface and a value
When a variable’s value is updated, the display on the user’s screen changes automatically
DependenciesIt's a support library - Android 2.1 (API level 7+)
Gradle 1.3.0-beta4 or higher is required
Beta release
DependenciesIn a top-level build.gradle add
In each module
Simple usage - Binding Data
Simple usage - Binding Data
Simple usage - Binding DataThe magic
Other option
Simple usage - Binding Events
More optionsUse imports
Alies
More optionsReferencing static fields and methods in expressions
More options - include
Expression LanguageMathematical + - / * %String concatenation +Logical && ||Binary & | ^Unary + - ! ~Shift >> >>> <<Comparison == > < >=
<=instanceofGrouping ()
Literals - character, String, numeric, null
CastMethod callsField accessArray access []Ternary operator ?:
Expression LanguageNot supported
thissupernewExplicit generic invocation
ObservableObservable Objects
listen for changes of all properties on that object
ObservableFieldslisten for changes of a field of that object
Observable Collectionslisten for changes on dynamic structures to
hold data
Observable Objects
ObservableFields
Observable CollectionsObservableArrayMap ObservableArrayList
Further Readingdeveloper.android.com/tools/data-binding/guide.html
Our app
ArchitectureStarwarsActivi
ty
CrawlLoader OpeningCrawl
mCrawlLoader.startLoading()
new OpeningCrawl
onLoadFinishListener.onLoadFinish(openingCrawl)
Every ~5 seconds
findViewById(R.id.asw_tv_episode);findViewById(R.id.asw_tv_crawl);
mEpisodeTextView.setText(...);mCrawlTextView.setText(...);mCrawlTextView.startAnimation();
Data Binding could be the mess
Downside- Define stuff in XML- Not debuggable- XML not unit tested- Run-time errors instead compile time- Bad IDE support
MVP - The Best Simple Friend
Why MVP?- Decoupled layers
- Easy to debug
- Fully testable business logic, data model
MVP vs DataBindingPresenter react on what happen in the view, retrieves data, formats and display back in the viewData Binding will take over the main responsibilities of the presenter (react and display). Rest - will go to the enhanced Model - ViewModel
MVVM
https://en.wikipedia.org/wiki/Model_View_ViewModel
MVVM ArchitectureStarwarsActivity
CrawlLoader OpeningCrawl
mCrawlLoader.startLoading()
new OpeningCrawl
onLoadFinishListener.onLoadFinish(openingCrawl)
Every ~5 seconds
StarWarsViewModel
Data Binding
Code
https://github.com/parahall/StarWarsDataBinding.git
Layout - ActivityStarWars.xml
Layout - ActivityStarWars.xml
StarWarsActivity
StarWarsActivity - no leak
StarWarsActivity - callbacks
StarWarsViewModel
StarWarsViewModel - react
StarWarsViewModel - retrieve
StarWarsViewModel - decide
* runOnUiThread - might be avoided using OttoBus event
CrawlLoader
So what we got?
Clean Debuggable codeDecoupled layerFully testable UI logic
Fun :)
Q?
