mysql_activity_main.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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/name"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:gravity="end"
        android:layout_margin="8dp"
        android:text="Name: "
        app:layout_constraintBottom_toBottomOf="@+id/name_enter"
        app:layout_constraintEnd_toStartOf="@+id/name_enter"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/name_enter"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginTop="8dp"
        android:hint="Enter name"
        android:inputType="text"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/pass"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:textSize="18sp"
        android:gravity="end"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:text="Password: "
        app:layout_constraintBottom_toBottomOf="@+id/pass_enter"
        app:layout_constraintEnd_toStartOf="@+id/pass_enter"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/pass_enter" />

    <EditText
        android:id="@+id/pass_enter"
        android:layout_width="250dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginTop="8dp"
        android:hint="Enter password"
        android:inputType="text"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/name_enter" />

    <Button
        android:id="@+id/login_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:text="Login"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/add_btn"
        app:layout_constraintTop_toTopOf="@+id/add_btn" />

    <Button
        android:id="@+id/list_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="List"
        app:layout_constraintEnd_toStartOf="@+id/add_btn"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/pass_enter" />

    <Button
        android:id="@+id/add_btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Add"
        app:layout_constraintEnd_toStartOf="@+id/login_btn"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/list_btn"
        app:layout_constraintTop_toTopOf="@+id/list_btn" />

    <ListView
        android:id="@+id/list_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/add_btn" />

    <android.support.constraint.Barrier
        android:id="@+id/barrier"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:barrierDirection="top" />

</android.support.constraint.ConstraintLayout>