title: my android hello world layout is not like good tutorial's shows
body: <p>i'm starting with android development , and i'm following the Google's training classes ,  everything was ok , and when i run the first layout its looks different from whats is shown in the tutorial page.</p>
  
  <p>There is the look of tutorial:</p>
  
  <p><img src="https://i.stack.imgur.com/osAem.png" alt="enter image description here"></p>
  
  <p>There is mine</p>
  
  <p><img src="https://i.stack.imgur.com/5MCIh.jpg" alt="enter image description here"></p>
  
  <p>so , the question is, what is wrong with my layout code above?</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:paddingBottom="@dimen/activity_vertical_margin"
      android:paddingLeft="@dimen/activity_horizontal_margin"
      android:paddingRight="@dimen/activity_horizontal_margin"
      android:paddingTop="@dimen/activity_vertical_margin"
      android:orientation="horizontal"
      tools:context="com.example.myfirstapp.MainActivity$PlaceholderFragment" &gt;
      &lt;EditText android:id="@+id/edit_message"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:hint="@string/edit_message"
          /&gt;
  
      &lt;Button
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:hint="@string/button_send"
          /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>