为什么不调用“ onPropertyChanged”？

Question

我正在编写具有2路数据绑定的应用程序。我可以获取编辑文本字段进行更新，但是我也正在尝试更新内部逻辑。我尝试通过在绑定上调用addOnPropertyChangedCallback(Observable.OnPropertyChangedCallback)来做到这一点，但是尽管检查了notifyPropertyChanged(int)是否由可观察对象调用，但并未调用回调

我尝试将@Bindable批注添加到in this stackoverflow question的getter和setter上，但无济于事。

AddItemObservable.kt

class AddItemObservable : BaseObservable(), AddItemImmutableObservable {

    private var name = ""
    private var quantity: Int? = null

    @Bindable
    override fun getName() = name

    fun setName(name: String) {
        if (this.name == name) {
            return
        }
        this.name = name
        notifyPropertyChanged(BR.name)
    }

    @Bindable
    override fun getQuantity() = quantity

    fun setQuantity(quantity: Int?) {
        if (this.quantity?.equals(quantity) == true) {
            return
        }
        this.quantity = quantity
        notifyPropertyChanged(BR.quantity)
    }
}

AndroidView.kt

class AndroidView : Fragment() {

    private lateinit var binding: FragmentAddItemBinding

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentAddItemBinding.inflate(inflater, container, false)
        binding.addItem = AddItemObservable()
        binding.addOnPropertyChangedCallback(object : Observable.OnPropertyChangedCallback() {
            override fun onPropertyChanged(sender: Observable?, propertyId: Int) {
                Log.i("VIEW", "updated")
            }
        })
        binding.lifecycleOwner = this

        return binding.root
    }
}

fragment_add_item.xml

<?xml version="1.0" encoding="utf-8"?>
<layout>
<data>
    <import type="tk.jonathancowling.inventorytracker.additem.AddItemObservable" />
    <variable
        name="addItem"
        type="AddItemObservable" />
</data>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <EditText
            android:id="@+id/editText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:layout_marginEnd="8dp"
            android:ems="10"
            android:hint="@string/add_item_name"
            android:inputType="textPersonName"
            android:text="@={addItem.name}"
            android:importantForAutofill="no"
            tools:ignore="UnusedAttribute" />

        <EditText
            android:id="@+id/editText2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:layout_marginEnd="8dp"
            android:ems="10"
            android:hint="@string/add_item_quantity"
            android:inputType="number"
            app:add_item_quantity="@={addItem.quantity}"
            android:importantForAutofill="no"
            tools:ignore="UnusedAttribute" />
    </LinearLayout>
</layout>

  

为简洁起见，省略了适配器

我希望OnPropertyChangedCallback被调用并在调用notifyPropertyChanged时（在将文本输入EditText之一时会记录为“更新”）。

Answer 1

要使其正常工作，您需要直接在addOnPropertyChangedCallback实例上调用Observable。例如，

val observableItem = AddItemObservable()
binding.addItem = observableItem
observableItem.addOnPropertyChangedCallback(object : Observable.OnPropertyChangedCallback() { 
    override fun onPropertyChanged(sender: Observable?, propertyId: Int) {
        Log.i("VIEW", "updated")
    } 
})