title: Elements overlapping on top of each other in relativeLayout
body: <p>I have created an Activity and used <code>RelativeLayout</code> which comes in by default in Android Studio. </p>
  
  <p>I am trying to place a button just before my <code>TextView</code> but I am unable to do that.</p>
  
  <p>Here is the result:</p>
  
  <p><img src="https://i.stack.imgur.com/KaWad.png" alt="enter image description here"></p>
  
  <p>Here is my code:</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:paddingLeft="@dimen/activity_horizontal_margin"
      android:paddingRight="@dimen/activity_horizontal_margin"
      android:paddingTop="@dimen/activity_vertical_margin"
      android:paddingBottom="@dimen/activity_vertical_margin"
      tools:context=".MyActivity"&gt;
  
      &lt;TextView
          android:id="@+id/heading"
          android:text="@string/hello_world"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          /&gt;
  
      &lt;Button
          android:id="@+id/button"
          android:text="@string/sachin_jain"
          android:layout_width="wrap_content"
          android:layout_height="20dp"
          android:layout_alignLeft="@+id/heading"
          android:layout_alignTop="@+id/heading"
          android:layout_centerHorizontal="true"
          /&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>Looks like I am missing something. Any help would be appreciated!!</p>