Placing the framelayout below the toolbar in ConstraintLayout

Question

I'm using the following code to place the FrameLayout below the toolbar.

<androidx.constraintlayout.widget.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"
    tools:context=".Dashboard">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="0dp"
        android:layout_height="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light">
        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">
        <TextView
            android:id="@+id/app_title"
            android:paddingTop="20dp"
            android:textAppearance = "@android:style/TextAppearance.Material.Large"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="App Name"
            android:textStyle="bold"/>
      
        </RelativeLayout>
    </androidx.appcompat.widget.Toolbar>


    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

  

</androidx.constraintlayout.widget.ConstraintLayout>

How can I be able to position the FrameLayout to be always below the toolbar without setting margin_top as actionbarsize? I would like to have finer control over its position.

Answer 1

You can make the height as match constraints (0dp), and constraint it at the bottom to the parent and at the top to the Toolbar

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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"
    tools:context=".Dashboard">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="0dp"
        android:layout_height="?attr/actionBarSize"
        android:theme="@style/ThemeOverlay.AppCompat.ActionBar"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:popupTheme="@style/ThemeOverlay.AppCompat.Light">

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

            <TextView
                android:id="@+id/app_title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:paddingTop="20dp"
                android:text="App Name"
                android:textAppearance="@android:style/TextAppearance.Material.Large"
                android:textStyle="bold" />

        </RelativeLayout>
    </androidx.appcompat.widget.Toolbar>


    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/toolbar" />


</androidx.constraintlayout.widget.ConstraintLayout>