java.lang.NullPointerException：缺少 ID 所需的视图：

Question

安卓工作室 3.6

在 app/build.gradle 中：

android {
viewBinding.enabled = true

这是我的 xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/bluetoothBottonMainContainer"
        android:layout_width="0dp"
        android:layout_height="104dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <View
            android:id="@+id/viewPointNotSelect"
            android:layout_width="16dp"
            android:layout_height="16dp"
            android:background="@drawable/circle_transparent"
            app:layout_constraintBottom_toBottomOf="@+id/separator"
            app:layout_constraintEnd_toStartOf="@+id/separator"
app:layout_constraintTop_toTopOf="parent" />

和另一个 xml unclude prev。xml:

 <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/bottonContainer"
        android:layout_width="0dp"
        android:layout_height="104dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <include
            android:id="@+id/qrBottonContainer"
            layout="@layout/qr_bottom_container"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent" />

这是我的活动：

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = QrBluetoothSwipeActivityBinding.inflate(layoutInflater)
        setContentView(binding.root)
}

该应用程序正在构建和运行。好的。

现在我移动 id - android:id="@+id/bluetoothBottonMainContainer"

到这样的外部容器：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/bluetoothBottonMainContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="0dp"
        android:layout_height="104dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <View
            android:id="@+id/viewPointNotSelect"
            android:layout_width="16dp"
            android:layout_height="16dp"
            android:background="@drawable/circle_transparent"
            app:layout_constraintBottom_toBottomOf="@+id/separator"
            app:layout_constraintEnd_toStartOf="@+id/separator"
            app:layout_constraintTop_toTopOf="parent" />

应用程序正在构建，但是在运行时我在这一行中收到运行时错误：

binding = QrBluetoothSwipeActivityBinding.inflate(layoutInflater)

错误：

10-25 11:11:51.290 E/AndroidRuntime(14128): FATAL EXCEPTION: main
10-25 11:11:51.290 E/AndroidRuntime(14128): Process: com.myproject.debug, PID: 14128
10-25 11:11:51.290 E/AndroidRuntime(14128): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myproject.debug/com.myproject.ui.actviity.QRBluetoothSwipeActivity}: java.lang.NullPointerException: Missing required view with ID: bluetoothBottonMainContainer
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.ActivityThread.-wrap11(ActivityThread.java)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.os.Handler.dispatchMessage(Handler.java:102)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.os.Looper.loop(Looper.java:148)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.ActivityThread.main(ActivityThread.java:5417)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at java.lang.reflect.Method.invoke(Native Method)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
10-25 11:11:51.290 E/AndroidRuntime(14128): Caused by: java.lang.NullPointerException: Missing required view with ID: bluetoothBottonMainContainer
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.myproject.databinding.BluetoothBottomContainerBinding.bind(BluetoothBottomContainerBinding.java:114)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.myproject.databinding.QrBluetoothSwipeActivityBinding.bind(QrBluetoothSwipeActivityBinding.java:76)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.myproject.databinding.QrBluetoothSwipeActivityBinding.inflate(QrBluetoothSwipeActivityBinding.java:62)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.myproject.databinding.QrBluetoothSwipeActivityBinding.inflate(QrBluetoothSwipeActivityBinding.java:52)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at com.myproject.ui.actviity.QRBluetoothSwipeActivity.onCreate(QRBluetoothSwipeActivity.kt:31)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.Activity.performCreate(Activity.java:6251)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
10-25 11:11:51.290 E/AndroidRuntime(14128):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
10-25 11:11:51.290 E/AndroidRuntime(14128):     ... 9 more
10-25 11:11:51.291 W/ActivityManager(  780):   Force finishing activity com.myproject.debug/com.myproject.ui.actviity.QRBluetoothSwipeActivity
10-25 11:11:51.307 I/Icing   (11529): Indexing done com.google.android.gms-apps

Answer 1

我遇到了这个问题，但就我而言，问题是include标志。我发现的解决方法是使视图 id 与包含的布局的根视图的 id 相同。

activity_layout.xml

<LinearLayout>
    <include android:id="@+id/widget1" layout="@layout/my_widget" />
</LinearLayout>

my_wideget.xml

<LinearLayout
    android:id="@+id/widget1">
</LinearLayout>

Answer 2

更新

这应该在最新的 Beta、Carnary 版本的 Android Studio 中修复

将视图绑定与材料选项卡布局选项卡项一起使用时仍然存在问题，此处报告且尚未修复。

这是 ViewBinding 中的错误，在以下位置的问题跟踪器中报告。

• https://issuetracker.google.com/issues/143729912
• https://issuetracker.google.com/issues/143683987

Answer 3

如果有人使用TabLayout并ViewBinding启用了此功能，那么您可能已经为TabItem. 从TabItemrseolved 中删除 id为我解决了这个问题。

Answer 4

请注意，如果您<merge>在包含的布局 XML 中使用，则逻辑是不同的，正如这里所指出的：
Exploring Android View Binding in Depth

If we try to give this an ID, the view binding won’t generate the ID in the binding class so we can’t access the view as we did in the case of the normal include.
In this case, we have PlaceholderBinding which is an auto-generated class for placeholder.xml (our <merge> layout file). We have to call its bind() method and pass the root view of the layout in which we included it.

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<include layout="@layout/placeholder" />

</androidx.constraintlayout.widget.ConstraintLayout>

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        binding = FragmentOrderBinding.inflate(layoutInflater, container, false)
        placeholderBinding = PlaceholderBinding.bind(binding.root)
        placeholderBinding.tvPlaceholder.text = getString(R.string.please_wait)
        return binding.root
    }

Answer 5

请检查，也许您在不同的模块中有相同的布局文件。

Answer 6

您应该删除 TabItem id 并使用 TabLayout API 来获取该项目，如果您使用的是 Material Design，则此解决方法有效

检查这个：Github 答案

Answer 7

如果您错误地将单元格绑定到 recyclerView 中的视图，您也会收到此错误。如果您将视图绑定到错误的布局，那么您将收到一条错误消息，指出它找不到预期的子视图。

这让我难倒了很长时间。

解决方案是确保您绑定到视图的布局与 ViewBinding 的布局相同。

例如，确保：

R.layout.my_new_view

一定会：

MyNewViewBinding

否则你会得到这个错误。