android-sms-gateway-server/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:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_gravity="center"
    android:baselineAligned="false"
    android:gravity="center|fill_vertical"
    tools:context="net.folivo.android.smsGatewayServer.MainActivity">

    <LinearLayout
        android:id="@+id/linLayoutServerOptions"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="4dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="4dp"
        android:background="@drawable/border"
        android:backgroundTintMode="src_atop"
        android:baselineAligned="false"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="10dp"
        app:layout_constraintBottom_toTopOf="@+id/linLayoutCertificateOptions"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <androidx.appcompat.widget.SwitchCompat
            android:id="@+id/switchStartServer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/btn_start_server" />

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:baselineAligned="true"
            android:gravity="center">

            <TextView
                android:id="@+id/txtViewUsername"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:labelFor="@id/editTextUserName"
                android:text="@string/txtView_username" />

            <EditText
                android:id="@+id/editTextUserName"
                android:layout_width="200dp"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:autofillHints="username"
                android:ems="10"
                android:hint="@string/editTextUserName_hint"
                android:inputType="textPersonName" />
        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center">

            <TextView
                android:id="@+id/textViewPassword"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:labelFor="@id/editTextPassword"
                android:text="@string/txtView_access_password" />

            <EditText
                android:id="@+id/editTextPassword"
                android:layout_width="200dp"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:autofillHints="password"
                android:ems="10"
                android:hint="@string/editTextPasswort_hint"
                android:inputType="textPassword" />
        </LinearLayout>

    </LinearLayout>

    <LinearLayout
        android:id="@+id/linLayoutCertificateOptions"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="4dp"
        android:background="@drawable/border"
        android:gravity="center"
        android:orientation="vertical"
        android:padding="10dp"
        app:layout_constraintBottom_toTopOf="@id/linLayoutDeleteMessagesOptions"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/linLayoutServerOptions">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center">

            <TextView
                android:id="@+id/textViewPathKeyStore"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:labelFor="@id/editTextPathKeyStore"
                android:text="@string/txtView_keystore_path" />

            <EditText
                android:id="@+id/editTextPathKeyStore"
                android:layout_width="144dp"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:autofillHints=""
                android:ems="10"
                android:inputType="textUri" />

            <ImageButton
                android:id="@+id/buttonCertificate"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:contentDescription="@string/btn_certificate_content_Description"
                app:srcCompat="?android:attr/actionModeFindDrawable" />

        </LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center">

            <TextView
                android:id="@+id/textViewKeyStorePassword"
                android:layout_width="150dp"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:labelFor="@id/editTextKeyStorePassword"
                android:text="@string/txtView_keystore_password" />

            <EditText
                android:id="@+id/editTextKeyStorePassword"
                android:layout_width="200dp"
                android:layout_height="wrap_content"
                android:layout_weight="3"
                android:autofillHints=""
                android:ems="10"
                android:inputType="textPassword" />

        </LinearLayout>

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

    </LinearLayout>

    <LinearLayout
        android:id="@+id/linLayoutDeleteMessagesOptions"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="4dp"
        android:gravity="center"
        android:orientation="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/linLayoutCertificateOptions">

        <Button
            android:id="@+id/buttonDeleteMessages"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/btn_delete_messages" />
    </LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>