activity_main.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <data>
        <variable name="loginViewModel" type="dev.kevinle.exploremvvm.viewmodel.LoginViewModel"/>
        <variable name="handler" type="dev.kevinle.exploremvvm.viewmodel.LoginViewModel" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_horizontal"
        android:orientation="vertical"
        android:paddingBottom="@dimen/activity_vertical_margin"
        android:paddingLeft="@dimen/activity_horizontal_margin"
        android:paddingRight="@dimen/activity_horizontal_margin"
        android:paddingTop="@dimen/activity_vertical_margin"
        tools:context=".LoginActivity">

        <ScrollView
            android:id="@+id/login_form"
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <LinearLayout
                android:id="@+id/email_login_form"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical">

                <android.support.design.widget.TextInputLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <EditText
                        android:id="@+id/email"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:hint="@string/prompt_email"
                        android:inputType="textEmailAddress"
                        android:maxLines="1"
                        android:text="@={loginViewModel.email}"/>

                </android.support.design.widget.TextInputLayout>

                <android.support.design.widget.TextInputLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <EditText
                        android:id="@+id/password"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:hint="@string/prompt_password"
                        android:imeActionId="@+id/login"
                        android:imeActionLabel="@string/action_sign_in_short"
                        android:imeOptions="actionUnspecified"
                        android:inputType="textPassword"
                        android:maxLines="1"
                        android:text="@={loginViewModel.password}"/>

                </android.support.design.widget.TextInputLayout>

                <Button
                    android:id="@+id/email_sign_in_button"
                    style="?android:textAppearanceSmall"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginTop="16dp"
                    android:text="@string/action_sign_in"
                    android:textStyle="bold"
                    android:onClick="@{handler.onClick}"/>

                <ProgressBar
                    android:id="@+id/login_progress"
                    style="?android:attr/progressBarStyleLarge"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_marginTop="8dp"
                    android:layout_gravity="center_horizontal"
                    android:visibility="@{loginViewModel.busy}" />

            </LinearLayout>
        </ScrollView>
    </LinearLayout>
</layout>