问题
I have a NestedScrollView within a CoordinatorLayout and it contains a recyclerView. The whole fragment, which is very long, has no scroll momentum and I'm not sure what I can do to fix it. I previously had this problem with higher Android versions and was able to include
android:nestedScrollingEnabled="false"
to solve my problem. However, that was added in api 21 and my project supports 19+. My app still has no momentum on this fragment for api 19 devices.
Below is my xml:
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:background="@color/primary_color"
android:fitsSystemWindows="true">
<android.support.v4.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="android.support.design.widget.AppBarLayout$ScrollingViewBehavior">
<android.support.percent.PercentRelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:nestedScrollingEnabled="false">
<ImageView
android:id="@+id/logo"
android:src="@drawable/logo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/profile_margin_medium_huge"
android:layout_marginBottom="46dp"
android:layout_marginRight="@dimen/activity_horizontal_margin"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_alignParentEnd="true"/>
<TypefaceTextView
android:id="@+id/textview_title"
android:layout_below="@id/logo"
android:text="@string/title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
style="@style/myStyle"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginRight="@dimen/activity_horizontal_margin"
android:layout_marginBottom="16dp"
android:layout_alignParentLeft="true"/>
<TypefaceTextView
android:id="@+id/textview_byline"
android:text="@string/byline"
android:layout_width="match_parent"
android:layout_height="wrap_content"
style="@style/myStyle"
android:layout_below="@id/textview_title"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginRight="@dimen/activity_horizontal_margin"
android:layout_marginBottom="40dp"/>
<RadioGroup
android:id="@+id/radiogroup_filter"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:layout_below="@id/textview_byline"
android:layout_alignParentRight="true"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginRight="@dimen/activity_horizontal_margin"
android:layout_marginBottom="@dimen/activity_vertical_margin">
<TypefaceRadioButton
android:id="@+id/button_filter_new"
android:text="@string/filter_new"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="@style/buttonStyleRadio"
android:theme="@style/ButtonSecondary"
android:button="@null"/>
<TypefaceRadioButton
android:id="@+id/button_filter_history"
android:text="@string/filter_history"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="@style/ButtonStyleRadio"
android:theme="@style/ButtonSecondary"
android:layout_alignParentRight="true"
android:button="@null"/>
</RadioGroup>
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerview"
android:nestedScrollingEnabled="false"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/radiogroup_filter"
android:layout_marginLeft="@dimen/activity_horizontal_margin"
android:layout_marginRight="@dimen/activity_horizontal_margin"
android:layout_marginBottom="50dp"/>
<android.support.percent.PercentRelativeLayout
android:id="@+id/container_links"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/recyclerview"
android:visibility="gone">
<ImageView
android:id="@+id/image_link_1"
app:layout_widthPercent="100%"
app:layout_aspectRatio="158%"
android:scaleType="centerCrop"
android:layout_alignParentTop="true"/>
<TypefaceTextView
android:id="@+id/text_link_1"
android:text="@string/text_1"
app:layout_widthPercent="100%"
app:layout_aspectRatio="158%"
android:gravity="bottom|left"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="32dp"
android:paddingBottom="32dp"
style="@style/myStyle"
android:layout_alignParentTop="true"/>
<ImageView
android:id="@+id/image_link_2"
app:layout_widthPercent="100%"
app:layout_aspectRatio="158%"
android:scaleType="centerCrop"
android:layout_below="@id/image_link_1"/>
<TypefaceTextView
android:id="@+id/text_link_2"
android:text="@string/text_2"
app:layout_widthPercent="100%"
app:layout_aspectRatio="158%"
android:gravity="bottom|right"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="32dp"
android:paddingBottom="32dp"
android:layout_below="@id/image_link_1"
style="@style/myStyle"/>
</android.support.percent.PercentRelativeLayout>
</android.support.percent.PercentRelativeLayout>
</android.support.v4.widget.NestedScrollView>
回答1:
I was able to recreate your symptoms in my test project. I fixed it be adding the following code in onCreate() for the activity:
final RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerview);
recyclerView.setOnFlingListener(new RecyclerView.OnFlingListener() {
@Override
public boolean onFling(int velocityX, int velocityY) {
recyclerView.dispatchNestedFling(velocityX, velocityY, false);
return false;
}
});
I added a fling listener to the RecyclerView, and in onFling(), I call dispatchNestedFling() to let the parent know that a fling is occurring. The parent can then consume the fling or observe the child fling.
https://developer.android.com/reference/android/support/v4/view/NestedScrollingChild.html#dispatchNestedFling(float, float, boolean)
dispatchNestedFling
added in version 22.1.0 boolean dispatchNestedFling (float velocityX, float velocityY, boolean consumed) Dispatch a fling to a nested scrolling parent.
This method should be used to indicate that a nested scrolling child has detected suitable conditions for a fling. Generally this means that a touch scroll has ended with a velocity in the direction of scrolling that meets or exceeds the minimum fling velocity along a scrollable axis.
If a nested scrolling child view would normally fling but it is at the edge of its own content, it can use this method to delegate the fling to its nested scrolling parent instead. The parent may optionally consume the fling or observe a child fling.
This is working on my emulator running API 19. Obviously, YMMV.
回答2:
There is a simpler way:
Java
recyclerView.setNestedScrollingEnabled(false);
Kotlin
recyclerView.isNestedScrollingEnabled = false
来源：https://stackoverflow.com/questions/43287798/api-19-scrollview-no-momentum