Basic ConstraintLayout (Toolbar, fragment container, and bottom nav)

Question

I'm adapting to Kotlin and ConstraintLayouts for Android. I'm trying to have a simple layout that has a toolbar and a bottom navigation view.

Here is my current xml:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    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.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimaryDark"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/app_name"
            android:textColor="@android:color/white"
            android:textSize="@dimen/toolbar_title_text_size"
            android:textStyle="bold" />

    </android.support.v7.widget.Toolbar>

    <FrameLayout
        android:id="@+id/fragment_container"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:background="@color/colorAccent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@id/toolbar"
        app:layout_constraintBottom_toTopOf="@id/bottom_navigation_view"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_navigation_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:menu="@menu/menu_main" />

</android.support.constraint.ConstraintLayout>

Unfortunately, I'm misunderstanding something and cannot seem to get the fragment container to fill the space between the toolbar and the bottom navigation.

Can someone steer me in the correct direction?

Answer 1

Height in your fragment container needs to be 0dp, which is the equivalent of "MATCH_CONSTRAINT".

android:layout_height="0dp"

You can look it up here ConstraintLayout.

It should be

<FrameLayout
    android:id="@+id/fragment_container"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:background="@color/colorAccent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintTop_toBottomOf="@id/toolbar"
    app:layout_constraintBottom_toTopOf="@id/bottom_navigation_view"/>