我是
android studio
的新手。在 binding
中使用 recyclerview adapter
时,出现以下错误:缺少带有 ID 的所需视图
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.co_investorux_ui, PID: 18057
java.lang.NullPointerException: Missing required view with ID: com.example.co_investorux_ui:id/app_name
at com.example.co_investorux_ui.databinding.ActivityMainBinding.bind(ActivityMainBinding.java:151)
at com.example.co_investorux_ui.RecyclerViewAdapter.onCreateViewHolder(MainActivity.kt:205)
at com.example.co_investorux_ui.RecyclerViewAdapter.onCreateViewHolder(MainActivity.kt:183)
at androidx.recyclerview.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:7295)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6416)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6300)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6296)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2330)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1631)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1591)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:668)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4309)
at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:4012)
at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4578)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1873)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at com.sothree.slidinguppanel.SlidingUpPanelLayout.onLayout(SlidingUpPanelLayout.java:863)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at androidx.appcompat.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:536)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:779)
at android.view.View.layout(View.java:21912)
at android.view.ViewGroup.layout(ViewGroup.java:6260)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3080)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2590)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1721)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7598)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:966)
at android.view.Choreographer.doCallbacks(Choreographer.java:790)
at android.view.Choreographer.doFrame(Choreographer.java:725)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:951)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
当我不使用
binding
时,它运行良好,没有错误。
没有
binding
的代码
//recyclerview adapter
class RecyclerViewAdapter(
val itemList: ArrayList<CoinList>,
val inflater: LayoutInflater
) : RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>(), Filterable {
private var searchList: ArrayList<CoinList>? = null
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val name: TextView
val count: TextView
init {
name = itemView.findViewById(R.id.coin_name)
count = itemView.findViewById(R.id.coin_count)
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = inflater.inflate(R.layout.item_view, parent, false)
return ViewHolder(view)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.name.setText(itemList.get(position).name)
holder.count.setText(itemList.get(position).count)
holder.itemView.setOnClickListener {
}
}
override fun getItemCount(): Int {
return itemList.size
}
}
使用
binding
进行编码
// recyclerview adapter
class RecyclerViewAdapter(
val itemList: ArrayList<MainActivity.CoinList>,
val inflater: LayoutInflater
) : RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>(), Filterable {
private var searchList: ArrayList<MainActivity.CoinList>? = null
class ViewHolder(val binding: ActivityMainBinding) : RecyclerView.ViewHolder(binding.root) {
val name: TextView
val count: TextView
init {
name = itemView.findViewById(R.id.coin_name)
count = itemView.findViewById(R.id.coin_count)
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = inflater.inflate(R.layout.item_view, parent, false)
return ViewHolder(ActivityMainBinding.bind(view))
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.name.setText(itemList.get(position).name)
holder.count.setText(itemList.get(position).count)
val slidePanel = holder.binding.mainFrame
holder.itemView.setOnClickListener {
val state = slidePanel.panelState
// Open slidePanel when it closed.
if (state == SlidingUpPanelLayout.PanelState.COLLAPSED) {
slidePanel.panelState = SlidingUpPanelLayout.PanelState.ANCHORED
}
// Close slidePanel when it open
else if (state == SlidingUpPanelLayout.PanelState.EXPANDED) {
slidePanel.panelState = SlidingUpPanelLayout.PanelState.COLLAPSED
}
}
}
override fun getItemCount(): Int {
return itemList.size
}
}
xml
代码
<com.sothree.slidinguppanel.SlidingUpPanelLayout 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:id="@+id/mainFrame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="bottom"
app:umanoDragView="@id/slide_layout"
app:umanoPanelHeight="16dp"
tools:context=".MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/first_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="430dp"
android:paddingBottom="15dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/search_view" />
</androidx.constraintlayout.widget.ConstraintLayout>
<androidx.fragment.app.FragmentContainerView
android:id="@+id/slide_layout"
android:layout_width="match_parent"
android:layout_height="430dp"
android:background="#ffffff"></androidx.fragment.app.FragmentContainerView>
</com.sothree.slidinguppanel.SlidingUpPanelLayout>
我正在实现一个当单击
sildinguppanellayout
的 itemview
时调用 recyclerview
的函数,但我无法解决该错误。
你能让我知道我做错了什么吗?
ActivityMainBinding
只会绑定从 activity_main.xml
创建的视图(注意命名)。要绑定从 item_view.xml
创建的视图,您需要使用 ItemViewBinding.bind(view)
。
构建 -> 清理对我有用