ViewStub 元素找不到 BindingAdapter

如何解决ViewStub 元素找不到 BindingAdapter

我有一个带有 ViewStub 的 XML 布局。我创建了一个绑定适配器 setLayout 来设置 ViewStub 将膨胀的布局。

<?xml version="1.0" encoding="utf-8"?>
<layout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <import type="android.view.View"/>
        <variable
            name="viewModel"
            type="com.smellydogcoding.westvirginiaelectronicfieldguidedistrict.ui.codeDetail.CodeDetailViewModel" />
    </data>

    <ScrollView
        android:id="@+id/codeDetailsScrollView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <ViewStub
                android:id="@+id/retailfood_viewStub"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:visibility="visible"
                app:setLayout="@{viewModel.searchRuleset}"
                app:viewModel="@{viewModel}"/>
        </LinearLayout>
    </ScrollView>
</layout>

绑定适配器

// set the layout for code details ViewStub
@BindingAdapter("setLayout")
fun ViewStub.setLayout(rule: String) {
    layoutResource = when (rule) {
        "retailfood" -> R.layout.stub_code_details_retail_food
        "general" -> R.layout.stub_code_details_general
        "recwater" -> R.layout.stub_code_details_recwater
        "citations" -> R.layout.stub_code_details_citations
        else -> R.layout.stub_code_details_other
    }
}

我在生成的绑定文件中不断收到错误：

cannot find symbol variable setLayout

if (this.retailfoodViewStub.isInflated()) this.retailfoodViewStub.getBinding().setVariable(BR.setLayout,viewModelSearchRulesetGetValue);
                                                                                              ^
  symbol:   variable setLayout
  location: class BR

好像 XML 布局找不到绑定适配器

编辑

这是绑定适配器所在的文件。绑定适配器不在伴随对象或其他命名对象中。

package com.smellydogcoding.westvirginiaelectronicfieldguidedistrict.ui

import android.app.Application
import android.view.ViewStub
import android.webkit.WebView
import android.widget.ImageView
import android.widget.TextView
import androidx.core.content.ContextCompat.getColor
import androidx.databinding.BindingAdapter
import com.smellydogcoding.westvirginiaelectronicfieldguidedistrict.R
import com.squareup.moshi.JsonAdapter
import com.squareup.moshi.Moshi
import com.squareup.moshi.Types
import com.squareup.moshi.kotlin.reflect.KotlinJsonAdapterFactory

// sets the background image for the program grid view recyclerview
@BindingAdapter("backgroundResource")
fun bindImageResource(imageView: ImageView,imagePath: String) {
    imageView.setImageResource(when (imagePath) {
        "code" -> R.drawable.code
        "restaurant" -> R.drawable.restaurant
        "hotelroom" -> R.drawable.hotelroom
        "well" -> R.drawable.well
        "septic" -> R.drawable.septic
        "pool" -> R.drawable.pool
        "tattoo" -> R.drawable.tattoo
        "mobilehomepark" -> R.drawable.mobilehomepark
        "daycare" -> R.drawable.daycare
        "raccoon" -> R.drawable.raccoon
        "tornado" -> R.drawable.tornado
        else -> R.drawable.code
    })
}

// sets the content for the code details WebViews
@BindingAdapter("webViewData")
fun WebView.webViewData(url: String?) {
    url?.let {
        settings.textZoom = 110
        loadDataWithBaseURL(null,url,"text/html","base64",null)
    }
}

// changes the font color for code details TextViews
@BindingAdapter("changeTextColor")
fun TextView.changeTextColor(text: String?) {
    text?.let {
        when (text) {
            "Priority","Yes" -> setTextColor(getColor(context,R.color.error)
            )
            "Priority Foundation","Potential" -> setTextColor(getColor(context,R.color.warning)
            )
        }
    }
}

// set the layout for code details ViewStub
@BindingAdapter("setLayout")
fun ViewStub.setLayout(rule: String) {
    layoutResource = when (rule) {
        "retailfood" -> R.layout.stub_code_details_retail_food
        "general" -> R.layout.stub_code_details_general
        "recwater" -> R.layout.stub_code_details_recwater
        "citations" -> R.layout.stub_code_details_citations
        else -> R.layout.stub_code_details_other
    }
}

// load JSON assets to use with a recyclerview
object JsonAsset {
    lateinit var application: Application
    inline fun <reified T: Any> getJson (name: String): List<T>? {

        val moshi = Moshi.Builder()
            .add(KotlinJsonAdapterFactory())
            .build()
        val json = application.assets.open(name).bufferedReader().use{ it.readText() }
        val listType = Types.newParameterizedType(List::class.java,T::class.java)
        val adapter: JsonAdapter<List<T>> = moshi.adapter(listType)

        return adapter.fromJson(json)
    }
}

解决方法

所以这个问题有点重复This Stack Overflow Question

但有一些区别。

tl;dr;你不能。

您不能将绑定适配器与 ViewStub 一起使用，因为当编译器创建绑定文件时，它将为 ViewStub 正在膨胀的视图寻找适配器，而不是为 ViewStub 本身寻找适配器。因此它永远不会找到适配器，并抛出错误。恕我直言，这个设计没有意义。如果我想将绑定适配器应用于我正在膨胀的视图，我会制作它们。

上面的 SO 问题确实提到了一种创建方法。不幸的是，它只允许您在 ViewStub 布局通过 onInflateListener 膨胀后应用它，而且我必须在 ViewStub 膨胀之前设置布局。

通过从 ViewStub XML 布局中删除 android:visibility="visible" and app:setLayout="@{viewModel.searchRuleset}" 并以编程方式设置相应片段中存根的布局，我找到了一个解决方案：

// set the layout for the ViewStub and inflate
val viewStubProxy : ViewStubProxy = binding.codeDetailsViewStub
viewStubProxy.viewStub?.layoutResource = when (viewModel.searchRuleset.value) {
    "retailfood" -> R.layout.stub_code_details_retail_food
    "general" -> R.layout.stub_code_details_general
    "recwater" -> R.layout.stub_code_details_recwater
    "citations" -> R.layout.stub_code_details_citations
    else -> R.layout.stub_code_details_other
}
viewStubProxy.viewStub?.inflate()

如果您使用数据绑定，则必须定位 ViewStubProxy 而不是 ViewStub 本身。

ViewStub 元素找不到 BindingAdapter

如何解决ViewStub 元素找不到 BindingAdapter

解决方法

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