update binding viewmodel
// Step 1: Import the necessary libraries
import androidx.databinding.Bindable
import androidx.databinding.Observable
import androidx.lifecycle.ViewModel
import androidx.databinding.PropertyChangeRegistry
// Step 2: Create a base class implementing Observable
open class BaseObservable : Observable {
private val callbacks: PropertyChangeRegistry by lazy { PropertyChangeRegistry() }
override fun addOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback) {
callbacks.add(callback)
}
override fun removeOnPropertyChangedCallback(callback: Observable.OnPropertyChangedCallback) {
callbacks.remove(callback)
}
// Step 3: Create a method to notify property changes
fun notifyPropertyChanged(fieldId: Int) {
callbacks.notifyCallbacks(this, fieldId, null)
}
}
// Step 4: Create your ViewModel class and inherit from BaseObservable
class MyViewModel : BaseObservable() {
// Step 5: Define properties with @Bindable annotation
@get:Bindable
var userName: String = ""
set(value) {
field = value
notifyPropertyChanged(BR.userName)
}
@get:Bindable
var userEmail: String = ""
set(value) {
field = value
notifyPropertyChanged(BR.userEmail)
}
// Step 6: Other ViewModel logic and methods...
}
Explanation for each step:
1. Import the necessary libraries (Bindable
, Observable
, ViewModel
, PropertyChangeRegistry
) required for data binding and view models in Kotlin Android development.
2. Create a base class BaseObservable
that implements the Observable
interface, allowing for registration and unregistration of callbacks for property changes.
3. Define a method notifyPropertyChanged()
in the BaseObservable
class to notify listeners about property changes.
4. Create a ViewModel class MyViewModel
that inherits from the BaseObservable
class to enable observable properties.
5. Define properties (userName
and userEmail
) within the MyViewModel
class with the @Bindable
annotation. This annotation is used to indicate that changes to these properties should trigger updates in the UI. When the setter for these properties is called, it updates the field and notifies property changes using notifyPropertyChanged()
by passing the corresponding BR (binding resource) ID.
6. Additional logic and methods specific to the ViewModel can be added as needed beyond defining bindable properties.