android-base16384/app/src/main/res/layout/activity_main.xml

<?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=".MainActivity">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/constraintLayout2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <ScrollView
            android:id="@+id/sv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginStart="32dp"
                android:layout_marginEnd="32dp"
                android:gravity="center"
                android:orientation="vertical">

                <com.google.android.material.textfield.TextInputLayout
                    android:id="@+id/stxt"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <com.google.android.material.textfield.TextInputEditText
                        android:id="@+id/ten"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:hint="@string/text_original" />
                </com.google.android.material.textfield.TextInputLayout>

                <Button
                    android:id="@+id/ben"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="@string/encode" />

                <com.google.android.material.textfield.TextInputLayout
                    android:id="@+id/dtxt"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <com.google.android.material.textfield.TextInputEditText
                        android:id="@+id/tde"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:hint="@string/text_encoded" />
                </com.google.android.material.textfield.TextInputLayout>

                <Button
                    android:id="@+id/bde"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="@string/decode" />
            </LinearLayout>
        </ScrollView>
    </androidx.constraintlayout.widget.ConstraintLayout>

    <TextView
        android:id="@+id/tti"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:fontFamily="@font/gotham"
        android:text="@string/app_name"
        android:textColor="?attr/colorOnSurface"
        android:textSize="36sp"
        app:layout_constraintBottom_toTopOf="@+id/constraintLayout2"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="32dp"
        android:layout_marginBottom="32dp"
        android:clickable="true"
        android:src="@drawable/ic_add"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>