How to place floating action button to right bottom of screen inside Constraint Layout?

Question

I have a ScrollView at the top, inside that I have a ConstraintLayout. Setting height to match_parent doesn't work in ConstraintLayout so the height doesn't match the screen. Inside my ConstraintLayout I have a floating action button and it doesn't stay at the right bottom of the screen, but it stays at the right bottom of ConstraintLayout.

Image of my screen

How can I make the floating action button stay at the right bottom of the screen?

Answer 1

If your FAB is inside constraint layout try like this

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

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/floatingActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:clickable="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:srcCompat="@drawable/icon" />
</android.support.constraint.ConstraintLayout>

Answer 2

 <android.support.design.widget.FloatingActionButton
    android:id="@+id/contactBtn"
    android:layout_width="53dp"
    android:layout_height="62dp"
    android:clickable="true"
    android:layout_gravity="bottom|right"
    app:srcCompat="@android:drawable/ic_menu_send" />

This Worked For me..

android:layout_gravity="bottom|right"