带有FloatingActionButton的InflateException来自官方设计库

Question

我使用Google支持设计库中的官方floatingactionbutton出现了一个bug。

android.view.InflateException: Binary XML file line #34: Error inflating class android.support.design.widget.FloatingActionButton
at android.view.LayoutInflater.createView(LayoutInflater.java:633)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:806)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:809)
at android.view.LayoutInflater.inflate(LayoutInflater.java:504)
at de.robv.android.xposed.XposedBridge.invokeOriginalMethodNative(Native Method)
at de.robv.android.xposed.XposedBridge.handleHookedMethod(XposedBridge.java:655)
at android.view.LayoutInflater.inflate(Unknown Source)
at android.view.LayoutInflater.inflate(LayoutInflater.java:414)
at ---.---.com.---.SubCategoryFragment.onCreateView(SubCategoryFragment.java:47)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:1789)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:955)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1138)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:740)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1501)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:458)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5221)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:117)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Constructor.newInstance(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:288)
at android.view.LayoutInflater.createView(LayoutInflater.java:607)
... 24 more
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.graphics.drawable.Drawable android.graphics.drawable.Drawable$ConstantState.newDrawable()' on a null object reference
at android.graphics.drawable.LayerDrawable$ChildDrawable.<init>(LayerDrawable.java:968)
at android.graphics.drawable.LayerDrawable$LayerState.<init>(LayerDrawable.java:1014)
at android.graphics.drawable.RippleDrawable$RippleState.<init>(RippleDrawable.java:910)
at android.graphics.drawable.RippleDrawable.createConstantState(RippleDrawable.java:901)
at android.graphics.drawable.RippleDrawable.createConstantState(RippleDrawable.java:90)
at android.graphics.drawable.LayerDrawable.mutate(LayerDrawable.java:932)
at android.graphics.drawable.RippleDrawable.mutate(RippleDrawable.java:891)
at android.view.View.applyBackgroundTint(View.java:16324)
at android.view.View.setBackgroundDrawable(View.java:16193)
at android.support.design.widget.FloatingActionButton.access$201(FloatingActionButton.java:56)
at android.support.design.widget.FloatingActionButton$1.setBackgroundDrawable(FloatingActionButton.java:118)
at android.support.design.widget.FloatingActionButtonLollipop.setBackgroundDrawable(FloatingActionButtonLollipop.java:75)
at android.support.design.widget.FloatingActionButton.<init>(FloatingActionButton.java:131)
at android.support.design.widget.FloatingActionButton.<init>(FloatingActionButton.java:79)
... 27 more

   <android.support.design.widget.FloatingActionButton
        android:id="@+id/myFABSubCat"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true"
        android:layout_alignParentRight="true"
        android:layout_margin="16dp"
        android:backgroundTint="@color/accent"
        android:src="@drawable/add_icon"
        app:borderWidth="0dp"
        app:elevation="4sp" />

下面是我的app主题：

<resources>

    <!-- Base application theme. -->
    <style name="MBTIAppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <item name="colorPrimary">@color/primary</item>
        <item name="colorPrimaryDark">@color/primaryDark</item>
        <item name="colorAccent">@color/accent</item>
        <item name="android:windowContentOverlay">@null</item>
    </style>

    <style name="ThemeNoActionBar" parent="MBTIAppTheme">
        <item name="windowActionBar">false</item>
    </style>

</resources>

是的，我正在使用AppCompattivity。

我注意到我使用的是较旧版本的AppCompat：

com.android.support:appcompat-v7:22.1.1

compile 'com.android.support:design:22.2.0'

minSdkVersion 16
targetSdkVersion 22

这是一个已知的bug还是可能我做错了什么？

Answer 1

com.android.support:Appcompat-v7:21+在运行android 5.1(API级别21）之前的设备上增加了对着色小部件的支持。要使用它，请确保扩展或设置AppCompat主题，并使用app:backgroundtint而不是android:backgroundtint。

示例：

<android.support.design.widget.FloatingActionButton 
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="16dp"
    android:src="@drawable/icon"
    app:backgroundTint="@color/accent"
    app:borderWidth="0dp" />