<?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools           = "http://schemas.android.com/tools"
     android:id            = "@+id/activity_main"
     android:layout_width  = "match_parent"
     android:layout_height = "match_parent"
     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         = "com.wenchen.myfirebase.MainActivity">
   <TextView
       android:id            = "@+id/txt_user"
       android:layout_width  = "wrap_content"
       android:layout_height = "wrap_content"
       android:paddingBottom = "@dimen/activity_horizontal_margin"
       android:paddingTop    = "@dimen/activity_horizontal_margin"
       android:textSize      = "20dp" />
   <LinearLayout
       android:layout_width  = "match_parent"
       android:layout_height = "wrap_content"
       android:orientation   = "vertical">
     <com.google.android.material.textfield.TextInputLayout
         android:layout_width  = "match_parent"
         android:layout_height = "wrap_content">
       <EditText
           android:id            = "@+id/name"
           android:layout_width  = "match_parent"
           android:layout_height = "wrap_content"
           android:hint          = "@string/name"
           android:inputType     = "textCapWords"
           android:maxLines      = "1" />
     </com.google.android.material.textfield.TextInputLayout>
     <com.google.android.material.textfield.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/email"
         android:inputType     = "textEmailAddress"
         android:maxLines      = "1" />
     </com.google.android.material.textfield.TextInputLayout>
     <Button
         android:id               = "@+id/btn_save"
         style                    = "?android:textAppearanceSmall"
         android:layout_width     = "match_parent"
         android:layout_height    = "wrap_content"
         android:layout_marginTop = "16dp"
         android:background       = "@color/colorPrimary"
         android:text             = "@string/action_save"
         android:textColor        = "@android:color/white"
         android:textStyle        = "bold" />
   </LinearLayout>
 </LinearLayout>