Why does it shows good in the editor and something completely different in the emulator?

Question

I'm designing my Android app in Android studio. In design view it looks like I want to but in the emulator completely different. All constraints have been added. And I would like to know how to fix the bottom bar navigation view. What should I do?

Xml code:

<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"
    android:fitsSystemWindows="true">

    <ScrollView
        android:id="@+id/scrollView3"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/background_color"
        android:scrollbars="none"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintVertical_bias="1.0">

        <androidx.constraintlayout.widget.ConstraintLayout
            android:id="@+id/constraintLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginBottom="623dp"
            android:background="@color/pink2">

            <TextView
                android:id="@+id/textView7"
                android:layout_width="118dp"
                android:layout_height="wrap_content"
                android:layout_marginStart="32dp"
                android:layout_marginTop="32dp"
                android:text="Hello!"
                android:textColor="@color/black"
                android:textSize="30sp"
                android:textStyle="bold"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />

            <ImageView
                android:id="@+id/imageView"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginBottom="-30dp"
                android:scaleType="fitEnd"
                app:layout_constraintBottom_toBottomOf="parent"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:srcCompat="@drawable/asset_3"
                tools:srcCompat="@drawable/asset_2" />

        </androidx.constraintlayout.widget.ConstraintLayout>
    </ScrollView>

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        style="@style/Widget.MaterialComponents.BottomNavigationView.Colored"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="12dp"
        android:paddingBottom="16dp"
        app:itemIconSize="24dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:menu="@menu/bottom_navigation_menu" />

</androidx.constraintlayout.widget.ConstraintLayout>

Answer 1

What's wrong with the bottom navigation view? If you mean the light bar above it, it´s the gesture soft navigation bar, you can´t hide it, unless you request your activity window to enter fullscreen, but I think you don't want that. I suggest you to remove the ConstraintLayout marginBottom and try some different scaleTypes in the ImageView, like: android:scaleType="center" or android:scaleType="centerCrop".