custom floating action button hidden behind toolbar

Question

I want to display a custom floating action button on top left corner of screen. There is Extended floating action button but it doesn't serve my purpose because i want a button with two images , one back icon and another activity image icon. So to achieve this look i used a custom cardview. But the problem is the button is hidden behind toolbar. How to bring it forward, i used elevation doesn't seem to be working.

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
    tools:context=".MainActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <androidx.appcompat.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="@dimen/height_toolbar"
            android:background="@drawable/background_small"
            app:popupTheme="@style/AppTheme.PopupOverlay">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical">

                <androidx.constraintlayout.widget.ConstraintLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@drawable/nav_button_image"
                    android:orientation="horizontal"
                    android:paddingBottom="5dp">
                    <!-- toolbar counter 1-->
                    <LinearLayout
                        android:id="@+id/linearLayout_app_bar_toolbar_plants"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:orientation="vertical"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintEnd_toStartOf="@id/linearLayout_app_bar_toolbar_to_do"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toTopOf="parent">

                        <TextView
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:text="@string/plants"
                            android:textAllCaps="true"
                            android:textColor="@color/bg_color"
                            android:textSize="@dimen/text_size_textView_actionbar" />

                        <TextView
                            android:id="@+id/plant_count_appbar_main"
                            android:layout_width="wrap_content"
                            android:layout_height="@dimen/textView_size_actionbar"
                            android:layout_gravity="center"
                            android:text="0/0"
                            android:textAlignment="center"
                            android:textColor="@color/bg_color"
                            android:textSize="@dimen/text_size_textView_actionbar"
                            android:textStyle="bold" />
                    </LinearLayout>
                    <!-- toolbar counter 2-->
                    <LinearLayout
                        android:id="@+id/linearLayout_app_bar_toolbar_to_do"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:orientation="vertical"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintEnd_toStartOf="@id/linearLayout_app_bar_toolbar_warnings"
                        app:layout_constraintStart_toEndOf="@id/linearLayout_app_bar_toolbar_plants"
                        app:layout_constraintTop_toTopOf="parent">

                        <TextView
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:text="@string/to_do"
                            android:textAllCaps="true"
                            android:textColor="@color/bg_color"
                            android:textSize="@dimen/text_size_textView_actionbar" />

                        <TextView
                            android:id="@+id/todo_count_appbar_main"
                            android:layout_width="wrap_content"
                            android:layout_height="@dimen/textView_size_actionbar"
                            android:layout_gravity="center"
                            android:text="0/0"
                            android:textAlignment="center"
                            android:textColor="@color/bg_color"
                            android:textSize="@dimen/text_size_textView_actionbar"
                            android:textStyle="bold" />
                    </LinearLayout>
                    <!-- toolbar counter 3-->
                    <LinearLayout
                        android:id="@+id/linearLayout_app_bar_toolbar_warnings"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:orientation="vertical"
                        app:layout_constraintBottom_toBottomOf="parent"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintStart_toEndOf="@id/linearLayout_app_bar_toolbar_to_do"
                        app:layout_constraintTop_toTopOf="parent">

                        <TextView
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:text="@string/warnings"
                            android:textAllCaps="true"
                            android:textColor="@color/bg_color"
                            android:textSize="@dimen/text_size_textView_actionbar" />

                        <TextView
                            android:id="@+id/warning_count_appbar_main"
                            android:layout_width="@dimen/textView_size_actionbar"
                            android:layout_height="@dimen/textView_size_actionbar"
                            android:layout_gravity="center"
                            android:background="@drawable/red_circle"
                            android:text="0"
                            android:textAlignment="center"
                            android:textColor="@color/bg_color"
                            android:textSize="@dimen/text_size_textView_actionbar"
                            android:textStyle="bold" />
                    </LinearLayout>
                </androidx.constraintlayout.widget.ConstraintLayout>

                <RelativeLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:layout_marginTop="5dp"
                    android:layout_marginBottom="5dp"
                    android:orientation="vertical">

                    <ImageView
                        android:layout_width="wrap_content"
                        android:layout_height="@dimen/height_imageView_actionbar_logo"
                        android:layout_alignParentBottom="true"
                        android:scaleType="fitStart"
                        android:src="@drawable/gardify_logo_header" />
                </RelativeLayout>
            </LinearLayout>
        </androidx.appcompat.widget.Toolbar>

    </com.google.android.material.appbar.AppBarLayout>

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

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="80dp"
        android:layout_gravity="right"/>

    <androidx.cardview.widget.CardView
        android:layout_width="wrap_content"
        app:cardBackgroundColor="@color/colorPrimary"
        android:elevation="10dp"
        android:layout_marginTop="80dp"
        app:cardCornerRadius="0dp"
        app:popupTheme="@style/AppTheme.AppBarOverlay"
        android:layout_height="wrap_content">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="@dimen/margin_padding_size_small"
            android:orientation="horizontal">

            <ImageView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:layout_marginRight="10dp"
                android:src="@drawable/ic_back_arrow" />

            <ImageView
                android:layout_width="50dp"
                android:layout_height="50dp"
                android:src="@drawable/gardify_app_icon_to_do_kalender" />
        </LinearLayout>
    </androidx.cardview.widget.CardView>


</androidx.coordinatorlayout.widget.CoordinatorLayout>

Answer 1

Try using

app:elevation

instead of

android:elevation

Then set the elevation for cardview greater than the appbar/toolbar.

Answer 2

Try to move the <CardView /> element above the <AppBarLayout /> element