为什么android.content.res.Resources $ NotFoundException：文件res / drawable /低于API 21

Question

为什么我在API 21下遇到此问题？尽管我的项目与docs中提到的API 21以下版本兼容。

//For Gradle Plugin 2.0+
 android {
   defaultConfig {
     vectorDrawables.useSupportLibrary = true
    }
 }

因此，通常，我只是尝试在线性布局中设置背景（ android：background =“ @ drawable / bg_vlsm_config” ）。像这样。

<LinearLayout
        android:id="@+id/toplayout"
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:layout_height="wrap_content"
        android:background="@drawable/bg_vlsm_config"
        android:padding="10dp"
        android:layout_marginStart="10dp"
        android:layout_marginEnd="10dp"
        android:layout_marginBottom="10dp"
        android:elevation="5dp"
        android:layout_marginTop="5dp">
</LinearLayout>

这是我的 bg_vlsm_config.xml 文件。

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="@color/colorAccent"/>
            <corners android:radius="10dp"/>
        </shape>
    </item>
    <item android:bottom="5dp">
        <shape android:shape="rectangle">
            <solid android:color="?mVlsmBackground"/>
            <corners android:radius="10dp"/>

        </shape>
    </item>
</layer-list>

我只需要在任何视图中设置任何可绘制的xml，否则它也可以用作图标。但是我得到这样的东西...

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.androcitizen.easyipsubnetcalc/com.androcitizen.easyipsubnetcalc.Activities.VlsmActivity}: android.view.InflateException: Binary XML file line #25: Error inflating class <unknown>
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
        at android.app.ActivityThread.access$800(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5017)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)
     Caused by: android.view.InflateException: Binary XML file line #25: Error inflating class <unknown>
        at android.view.LayoutInflater.createView(LayoutInflater.java:621)
        at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)
        at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:756)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
        at com.androcitizen.easyipsubnetcalc.InputFragment.onCreateView(InputFragment.java:97)
        at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881)
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238)
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303)
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439)
        at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079)
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869)
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824)
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727)
        at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2663)
        at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2613)
        at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:246)
        at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:542)
        at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
        at android.app.Activity.performStart(Activity.java:5241)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
        at android.app.ActivityThread.access$800(ActivityThread.java:135) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:136) 
        at android.app.ActivityThread.main(ActivityThread.java:5017) 
        at java.lang.reflect.Method.invokeNative(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:515) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
        at dalvik.system.NativeStart.main(Native Method) 
     Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Constructor.constructNative(Native Method)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
        at android.view.LayoutInflater.createView(LayoutInflater.java:595)
        at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56) 
        at android.view.LayoutInflater.onCreateView(LayoutInflater.java:670) 
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:695) 
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:756) 
        at android.view.LayoutInflater.inflate(LayoutInflater.java:492) 
        at android.view.LayoutInflater.inflate(LayoutInflater.java:397) 
        at com.androcitizen.easyipsubnetcalc.InputFragment.onCreateView(InputFragment.java:97) 
        at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2600) 
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:881) 
        at androidx.fragment.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManagerImpl.java:1238) 
        at androidx.fragment.app.FragmentManagerImpl.moveToState(FragmentManagerImpl.java:1303) 
        at androidx.fragment.app.BackStackRecord.executeOps(BackStackRecord.java:439) 
        at androidx.fragment.app.FragmentManagerImpl.executeOps(FragmentManagerImpl.java:2079) 
        at androidx.fragment.app.FragmentManagerImpl.executeOpsTogether(FragmentManagerImpl.java:1869) 
        at androidx.fragment.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManagerImpl.java:1824) 
        at androidx.fragment.app.FragmentManagerImpl.execPendingActions(FragmentManagerImpl.java:1727) 
        at androidx.fragment.app.FragmentManagerImpl.dispatchStateChange(FragmentManagerImpl.java:2663) 
        at androidx.fragment.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManagerImpl.java:2613) 
        at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:246) 
        at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:542) 
        at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201) 
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171) 
        at android.app.Activity.performStart(Activity.java:5241) 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168) 
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
        at android.app.ActivityThread.access$800(ActivityThread.java:135) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:136) 
        at android.app.ActivityThread.main(ActivityThread.java:5017) 
        at java.lang.reflect.Method.invokeNative(Native Method) 
        at java.lang.reflect.Method.invoke(Method.java:515) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
        at dalvik.system.NativeStart.main(Native Method) 
     Caused by: android.content.res.Resources$NotFoundException: File res/drawable/bg_vlsm_config.xml from drawable resource ID #0x7f080079
        at android.content.res.Resources.loadDrawable(Resources.java:2101)
        at android.content.res.TypedArray.getDrawable(TypedArray.java:602)
        at android.view.View.<init>(View.java:3554)
        at android.view.ViewGroup.<init>(ViewGroup.java:470)
        at android.widget.LinearLayout.<init>(LinearLayout.java:176)
        at android.widget.LinearLayout.<init>(LinearLayout.java

然而，该应用程序已通过API 21正常运行。所以任何人都可以在这个问题上帮助我。自从两天以来，这真让我很烦。我仍然没有找到任何合适的解决方案。谢谢。