如何让 RecyclerView 在 Android PopupWindow 中工作？

如何解决如何让 RecyclerView 在 Android PopupWindow 中工作？

我已经阅读了几个类似的问题，但我无法做出任何答案。关键在于

val popupMenu = findViewById<RecyclerView>(R.id.popmenu)

总是返回空值。

这里是activity_popup.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"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/popupactivity"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".PopupActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/popmenu"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

这是设置弹出窗口的代码：

val inflater = getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
        val popupView = inflater.inflate(R.layout.activity_popup,null)
        popupWin = PopupWindow(popupView,popupWidth,popupHeight,true)
        val layoutMgr = linearlayoutmanager(applicationContext)
        val popupMenu = findViewById<RecyclerView>(R.id.popmenu)

我做错了什么？

解决方法

您可能正在 Activity 中运行此代码，findViewById() 在 Activity 的视图层次结构中查找视图。您应该搜索膨胀视图的层次结构

 val popupMenu = popupView.findViewById<RecyclerView>(R.id.popmenu)

,

我做错了什么？

您正在尝试在 current 视图层次结构中查找视图。您需要查看PopupWindow 的层次结构。

// Inflates a layout that's not attached to anything
val popupView = inflater.inflate(R.layout.activity_popup,null)

// Creates a PopupWinow with the given popupView that's not attached to anything
popupWin = PopupWindow(popupView,popupWidth,popupHeight,true)

val layoutMgr = LinearLayoutManager(applicationContext)

// Attempts to find the recycler view in *this* view hierchy,which does not exist
val popupMenu = findViewById<RecyclerView>(R.id.popmenu)

修复： 将最后一行更改为 popupView.findViewById<RecyclerView>(r.id.popmenu)，以便您在正确的视图层次结构中进行搜索。