如何让浮动按钮保持在布局的底部？

Question

我正在使用协调员布局，回收站视图和浮动按钮。不知何故，fab按钮不会停留在布局的底部。我希望按钮在滚动时保持在底部。我所知道的是，fab按钮占据了回收站视图中最后一项的最低位置。

列表activity.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <android.support.v7.widget.RecyclerView
            tools:listitem="@layout/activity_sample_05borangb_parent"
            android:id="@+id/recyclerView2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:scrollbars="vertical"/>

    </RelativeLayout>

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:foregroundGravity="bottom"
        android:layout_gravity="bottom|end"/>


</android.support.design.widget.CoordinatorLayout>

Answer 1

试试这个：

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recyclerView2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:scrollbars="vertical"/>

    </RelativeLayout>

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:foregroundGravity="bottom"
        android:layout_margin="16dp"
        android:layout_gravity="bottom|end"/>


</android.support.design.widget.CoordinatorLayout>

Answer 2

进行以下更改

<android.support.design.widget.CoordinatorLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <RelativeLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recyclerView2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:scrollbars="vertical"/>

    </RelativeLayout>

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:fabSize="normal"
        app:layout_anchor="@id/container"
        app:layout_anchorGravity="bottom|end"/>


</android.support.design.widget.CoordinatorLayout>

您需要指定layout_anchor和layout_anchorGravity

Answer 3

你不需要使用android.support.design.widget.CoordinatorLayout来实现这种相对布局绰绰有余。

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

        <android.support.v7.widget.RecyclerView
            tools:listitem="@layout/activity_sample_05borangb_parent"
            android:id="@+id/recyclerView2"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scrollbars="vertical" />

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentEnd="true" />

</RelativeLayout>