我想显示一个包含波纹的视图。启动叠加层时，应用程序崩溃。消除纹波时，一切正常。我添加了以下权限：
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
这是我使用的布局。
<?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>
<variable
name="data"
type="MyModel" />
</data>
<com.google.android.material.card.MaterialCardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="4dp"
android:layout_marginTop="4dp"
android:clickable="true"
android:focusable="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/selectableItemBackground"
android:gravity="center_vertical"
android:orientation="horizontal"
android:padding="8dp">
<de.hdodenhof.circleimageview.CircleImageView
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
app:setImageBitmap="@{data.appIcon}" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{data.name}"
android:textSize="16sp" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{data.packageName}"
android:textSize="12sp" />
</LinearLayout>
</LinearLayout>
</com.google.android.material.card.MaterialCardView>
</layout>
这是我得到的错误：
2018-11-05 17:15:36.073 10299-10299/be.vanlooverenkoen.riddle.app E/AndroidRuntime: FATAL EXCEPTION: main
Process: be.vanlooverenkoen.riddle.app, PID: 10299
android.view.InflateException: Binary XML file line #12: Binary XML file line #12: Error inflating class <unknown>
Caused by: android.view.InflateException: Binary XML file line #12: Error inflating class <unknown>
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance0(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:343)
at android.view.LayoutInflater.createView(LayoutInflater.java:647)
at com.android.internal.policy.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:58)
at android.view.LayoutInflater.onCreateView(LayoutInflater.java:720)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:788)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:730)
at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
at androidx.databinding.DataBindingUtil.inflate(DataBindingUtil.java:126)
at androidx.databinding.DataBindingUtil.inflate(DataBindingUtil.java:95)
at be.vanlooverenkoen.riddle.app.adapter.overlay.OverlayAppAdapter.onCreateViewHolder(OverlayAppAdapter.kt:47)
at be.vanlooverenkoen.riddle.app.adapter.overlay.OverlayAppAdapter.onCreateViewHolder(OverlayAppAdapter.kt:14)
at androidx.recyclerview.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6744)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5925)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5808)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5804)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3878)
at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3595)
at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4148)
at android.view.View.layout(View.java:20672)
at android.view.ViewGroup.layout(ViewGroup.java:6194)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:20672)
at android.view.ViewGroup.layout(ViewGroup.java:6194)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
at android.view.View.layout(View.java:20672)
at android.view.ViewGroup.layout(ViewGroup.java:6194)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:20672)
at android.view.ViewGroup.layout(ViewGroup.java:6194)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2792)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2319)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1460)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7183)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
at android.view.Choreographer.doCallbacks(Choreographer.java:761)
at android.view.Choreographer.doFrame(Choreographer.java:696)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
2018-11-05 17:15:36.077 10299-10299/be.vanlooverenkoen.riddle.app E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.UnsupportedOperationException: Failed to resolve attribute at index 13: TypedValue{t=0x2/d=0x7f0301b3 a=-1}
at android.content.res.TypedArray.getDrawableForDensity(TypedArray.java:946)
at android.content.res.TypedArray.getDrawable(TypedArray.java:930)
at android.view.View.<init>(View.java:5010)
at android.view.ViewGroup.<init>(ViewGroup.java:659)
at android.widget.LinearLayout.<init>(LinearLayout.java:244)
at android.widget.LinearLayout.<init>(LinearLayout.java:240)
at android.widget.LinearLayout.<init>(LinearLayout.java:236)
... 54 more
删除android:background时一切正常。
使用开关时，我也遇到同样的问题。我认为这与涟漪有关。
答案 0 :(得分：0)
似乎您在API级别小于21的设备上启动应用程序。您需要使用api小于21的选择器创建常规的drawable，而对于api 21或更高版本则需要创建ripple drawable。
答案 1 :(得分：0)
我正在使用?attr/selectableItemBackground，但没有将主题设置为叠加层。使用?android:attr/selectableItemBackground时，一切正常。创建自己的涟漪可绘制对象也可以。