Kotlin & Android Data Binding Library @takuji31

@takuji31 (Takuji Nishibayashi) Application Engineer at Hatena

Loves Kotlin

Kotlin 1.0.1-2 released

Android Data Binding Library

Official binding library for Android

Android Studio support

One way binding support

Two way binding support latest version

Can use with Kotlin

Define binding using layout XML

Auto generate binding class

Define binding 
 
 
 
 
 
 
 
 
 
 
 


Using binding class DataClassActivity : AppCompatActivity() {
 data class User(val name: String, val birthDay: String?)
 var users = listOf(
 User(name = "takuji31", birthDay = "1987/03/01"),
 User(name = "takuji32", birthDay = "1987/03/02"),
 User(name = "takuji33", birthDay = "1987/03/03"),
 User(name = "takuji24884", birthDay = null)
 )
 val binding: ActivityDataClassBinding by lazy {
 DataBindingUtil.setContentView(this, R.layout.activity_data_class)
 }
 override fun onCreate(savedInstanceState: Bundle?) {
 binding.user = users.last()
 binding.randomButtonClickListener = View.OnClickListener {
 binding.user = users[0]
 users = users.drop(1) + binding.user
 }
 }
 }

No more (ViewClass)findById(R.id.viewId)

Define binding 
 
 


Field access class MainActivity : AppCompatActivity() {
 val binding : ActivityMainBinding by lazy {DataBindingUtil.setContentView(this, R.layout.activity_main)} 
 override fun onCreate(savedInstanceState: Bundle?) {
 super.onCreate(savedInstanceState)
 binding.recyclerView.layoutManager = LinearLayoutManager(this)
 }
 }

Property observer

Observable data class class Counter : BaseObservable() {
 @get:Bindable
 var count : Int = 0
 set(value) {
 field = value
 notifyPropertyChanged(BR.count)
 }
 }


Define binding 
 
 
 
 
 
 
 
 
 


Change value class PropertyObserverActivity : AppCompatActivity() {
 val binding : ActivityPropertyObserverBinding by lazy { DataBindingUtil.setContentView( this, R.layout.activity_property_observer ) } 
 override fun onCreate(savedInstanceState: Bundle?) {
 val counter = Counter()
 binding.counter = counter
 binding.buttonClickListener = View.OnClickListener {
 counter.count += 1 }
 }
 }

Binding adapter

Define binding adapter object Adapters {
 @JvmStatic
 @BindingAdapter("android:text")
 fun convertZonedDateTimeToString (textView: TextView, zonedDateTime : ZonedDateTime) {
 val timeString = zonedDateTime.format( DateTimeFormatter.ofPattern("yyyy/MM/dd/ HH:mm:SS"))
 textView.text = timeString
 }
 }

Value converter

Issues with Kotlin

Can’t find converter written with Kotlin

Use Java

example : github.com/ takuji31/KotlinDataBinding

Enjoy Data Binding Life