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activity_phone_number.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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/phone_number"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    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="com.google.samples.smartlock.sms_verify.PhoneNumberActivity"
    android:orientation="vertical">

<TextView
            android:id="@+id/phone_number_label"
            android:labelFor="@+id/phone_number_field"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"

android:text="@string/phone_label" />

<EditText
            android:id="@+id/phone_number_field"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="3"

android:inputType="phone"
            android:editable="false"
            android:ems="10"
            style="@style/Widget.AppCompat.EditText" />

</LinearLayout>

<Button
        android:id="@+id/phone_number_submit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end"

android:text="@string/submit_sign_up"
        style="@style/Widget.AppCompat.Button.Colored" />
</LinearLayout>