浮动操作按钮重力不起作用

Question

I have a floating action button which should be in the bottom right corner, but apparently the gravity isn't working. It is shown in the top left corner. Here is my code:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout android:id="@+id/rl"
            xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

<ImageView
    android:id="@+id/iv"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="bottom|end"
    android:layout_margin="16dp"
    android:src="@mipmap/ic_action_send"
    app:backgroundTint="@color/colorPrimaryDark"
    app:layout_anchor="@id/iv"
    app:layout_anchorGravity="bottom|right|end"/>

</RelativeLayout>

Answer 1

I have a floating action button which should be in the bottom right corner, but apparently the gravity isn't working

it is the expected behavior unless you wrap your content around a CoordinatorLayout . Eg

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


     <ImageView
      android:id="@+id/iv"
      android:layout_width="match_parent"
      android:layout_height="match_parent"/>

 <android.support.design.widget.FloatingActionButton
       android:id="@+id/fab"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_gravity="bottom|end"
       android:layout_margin="16dp"
       android:src="@mipmap/ic_action_send"
       app:backgroundTint="@color/colorPrimaryDark"
       app:layout_anchor="@id/iv"
       app:layout_anchorGravity="bottom|right|end"/>
 </android.support.design.widget.CoordinatorLayout>

should do it. You can read more about the CoordinatorLayout here

Answer 2

使用android:layout_alignParentBottom="true"和android:layout_alignRight="@id/iv"作为FloatingActionButton参数。

Answer 3

使用android:layout_gravity="bottom|end"而不是app:layout_anchorGravity="bottom|right|end"将它放入最后的底部（右下角）

Answer 4

For FrameLayout, you can try:

<FrameLayout 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:fitsSystemWindows="true"
    tools:context="ch13mob.wifiofworldairports.fragment.FragmentWifiAirports">

    <include layout="@layout/wifi_list" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab_wifi"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|end"
        android:layout_margin="@dimen/fab_margin"
        android:src="@drawable/ic_wifi_black_24dp" />

</FrameLayout>

Answer 5

in case you're using RelativeLayout

<com.google.android.material.floatingactionbutton.FloatingActionButton
    android:id="@+id/fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="end|bottom"
    android:src="@drawable/arrow_back"
    android:contentDescription="Help"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:layout_margin="16dp" />

use

android:layout_alignParentBottom="true" 
android:layout_alignParentEnd="true"