我希望浮动动作按钮在滚动时显示或消失
但我的代码不起作用。我检查了其他类似的问题，但我不知道原因
请有人告诉我为什么会发生这些错误。
context$布局文件（为了缩短代码，我删除了约束属性。）
FATAL EXCEPTION: main
Process: com.knkj28.test, PID: 11926
android.view.InflateException: Binary XML file line #45: Could not inflate Behavior subclass com.knkj28.test.ScrollAwareFABBehavior
Caused by: java.lang.RuntimeException: Could not inflate Behavior subclass com.knkj28.test.ScrollAwareFABBehavior
at android.support.design.widget.CoordinatorLayout.parseBehavior(CoordinatorLayout.java:615)
at android.support.design.widget.CoordinatorLayout$LayoutParams.<init>(CoordinatorLayout.java:2652)
at android.support.design.widget.CoordinatorLayout.generateLayoutParams(CoordinatorLayout.java:1679)
at android.support.design.widget.CoordinatorLayout.generateLayoutParams(CoordinatorLayout.java:109)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:860)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:861)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
at com.knkj28.test.ListFragment.onCreateView(ListFragment.java:63)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2192)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1299)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149)
at android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103)
at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1984)
at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:626)
at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1268)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1116)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1642)
at android.view.View.measure(View.java:19785)
at android.support.constraint.ConstraintLayout.onMeasure(ConstraintLayout.java:1028)
at android.view.View.measure(View.java:19785)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:19785)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
at android.view.View.measure(View.java:19785)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at android.view.View.measure(View.java:19785)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:758)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:640)
at android.view.View.measure(View.java:19785)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6120)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:185)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:689)
at android.view.View.measure(View.java:19785)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2275)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1362)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1611)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1250)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6311)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:871)
at android.view.Choreographer.doCallbacks(Choreographer.java:683)
at android.view.Choreographer.doFrame(Choreographer.java:619)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:241)
at android.app.ActivityThread.main(ActivityThread.java:6217)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.NoSuchMethodException: <init> [class android.content.Context, interface android.util.AttributeSet]
at java.lang.Class.getConstructor0(Class.java:2204)
at java.lang.Class.getConstructor(Class.java:1683)
at android.support.design.widget.CoordinatorLayout.parseBehavior(CoordinatorLayout.java:609)
... 64 more
CoordinatorLayout.Behavior的子类 （完整路径：“com.knkj28.test.ScrollAwareFABBehavior”）
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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/play_list"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab_add_music_to_playlist"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_add_black_36dp"
android:visibility="visible"
app:layout_behavior="com.knkj28.test.ScrollAwareFABBehavior"/>
<android.support.design.widget.FloatingActionButton
android:id="@+id/fab_delete_music_from_playlist"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/ic_delete_black_36dp"
app:layout_behavior="com.knkj28.test.ScrollAwareFABBehavior"
android:visibility="visible"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_view"
android:layout_width="0dp"
android:layout_height="0dp"/>
</android.support.design.widget.CoordinatorLayout>
</android.support.constraint.ConstraintLayout>
答案 0 :(得分：0)
为什么不直接向RecyclerView添加滚动侦听器并隐藏/显示其中的浮动操作按钮？
rv.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
if (dy > 0) {
fab.hide();
} else {
fab.show();
}
}
});