求助：kotlin.UninitializedPropertyAccessException错误排查（适配器第69行）

我是Android开发新手，开发的com.example.kotlincountries应用抛出kotlin.UninitializedPropertyAccessException，提示lateinit property binding has not been initialized，错误位于CountryAdapter.kt第69行，尝试多种方案仍无法解决，特求助。

错误日志 #

AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.kotlincountries, PID: 15240
kotlin.UninitializedPropertyAccessException: lateinit property binding has not been initialized
at com.example.kotlincountries.adapter.CountryAdapter.onCountryClicked(CountryAdapter.kt:69)
at com.example.kotlincountries.databinding.ItemCountryBindingImpl$OnClickListenerImpl.onClick(ItemCountryBindingImpl.java:173)
at android.view.View.performClick(View.java:7506)
at android.view.View.performClickInternal(View.java:7483)
at android.view.View.-$$Nest$mperformClickInternal(Unknown Source:0)
at android.view.View$PerformClick.run(View.java:29334)
at android.os.Handler.handleCallback(Handler.java:942)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:201)
at android.os.Looper.loop(Looper.java:288)
at android.app.ActivityThread.main(ActivityThread.java:7872)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:936)

已配置与检查内容 #

Gradle配置 #

buildFeatures {
    viewBinding = true
    dataBinding = true
}

Item布局XML #

<layout
    xmlns:android="http://schemas.android.com/apk/res/android">

    <data>
        <variable
            name="country"
            type="com.example.kotlincountries.model.Country" />
        <variable
            name="listener"
            type="com.example.kotlincountries.adapter.CountryClickListener" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:onClick="@{listener::onCountryClicked}"
        android:orientation="horizontal">
        <TextView
            android:id="@+id/countryUuidText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:text="@{String.valueOf(country.uuid)}">

        </TextView>

        <ImageView
            android:id="@+id/imageView"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="2"
            android:padding="3dp"
            android:downloadUrl="@{country.imageUrl}">
            </ImageView>
        <LinearLayout
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:gravity="center_vertical"
            android:layout_weight="3">
            
            <TextView
                android:id="@+id/name"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@{country.countryName}"
                android:padding="5dp"
                android:textSize="18sp"
                android:textStyle="bold">

            </TextView>

            <TextView
                android:id="@+id/region"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@{country.countryRegion}"
                android:textSize="16sp"
                android:padding="5dp">


            </TextView>

        </LinearLayout>

    </LinearLayout>
</layout>

适配器代码 #

class CountryAdapter(val countryList:ArrayList<Country>): RecyclerView.Adapter<CountryAdapter.CountryViewHolder>(),CountryClickListener {
    private lateinit var binding : ItemCountryBinding


    class CountryViewHolder(var view:ItemCountryBinding) :RecyclerView.ViewHolder(view.root) {

    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CountryViewHolder {
        val inflater = LayoutInflater.from(parent.context)
        val binding = ItemCountryBinding.inflate(inflater, parent, false)

        return CountryViewHolder(binding)

    }

    override fun getItemCount(): Int {
        return  countryList.size
    }

    override fun onBindViewHolder(holder: CountryViewHolder, position: Int) {

        holder.view.country=countryList[position]
        holder.view.listener=this


    }
    fun updateCountryList(newCountryList:List<Country>){
       
        countryList.clear()
        countryList.addAll(newCountryList)
        notifyDataSetChanged()
    }

    override fun onCountryClicked(v: View) {
        val uuid=binding.countryUuidText.text.toString().toInt()
        val action=FeedFragmentDirections.actionFeedFragmentToCountryFragment(uuid)
        Navigation.findNavController(v).navigate(action)
    }
}

问题原因与解决方案 #

问题根源 #

你在适配器类中声明的private lateinit var binding : ItemCountryBinding从未被初始化——每个RecyclerView的ViewHolder都有自己独立的Binding实例（在onCreateViewHolder中创建并传入ViewHolder），而适配器类级别的Binding变量根本没有赋值，所以点击事件中访问它时必然抛出未初始化异常。

解决方案 #

方案1：通过DataBinding直接传递UUID（推荐）

这种方式更简洁，不需要通过View查找控件：

1. 修改XML布局中的点击事件，直接传递country.uuid和点击的View：

android:onClick="@{(v) -> listener.onCountryClicked(v, country.uuid)}"

2. 修改CountryClickListener接口的方法定义：

interface CountryClickListener {
    fun onCountryClicked(v: View, uuid: Int)
}

3. 删除适配器类中的private lateinit var binding : ItemCountryBinding变量，并修改onCountryClicked实现：

override fun onCountryClicked(v: View, uuid: Int) {
    val action=FeedFragmentDirections.actionFeedFragmentToCountryFragment(uuid)
    Navigation.findNavController(v).navigate(action)
}

方案2：通过点击View查找目标控件

如果不想修改接口定义，可以直接从点击的View中找到countryUuidText：

1. 删除适配器类中的private lateinit var binding : ItemCountryBinding变量
2. 修改onCountryClicked方法：

override fun onCountryClicked(v: View) {
    val uuidText = v.findViewById<TextView>(R.id.countryUuidText)
    val uuid = uuidText.text.toString().toInt()
    val action=FeedFragmentDirections.actionFeedFragmentToCountryFragment(uuid)
    Navigation.findNavController(v).navigate(action)
}

内容的提问来源于stack exchange，提问作者user16190280