title: Android make button 1/3 of screen width and height in relative layout
body: <p>I have some XML. In this XML there is a single button inside a relative layout. The relative layout takes up the entire screen. I want the button to have 1/3 of the screen width and height. How could I do this?</p>
  
  <p>Here is the XML:</p>
  
  <pre><code>    &lt;?xml version="1.0" encoding="utf-8"?&gt;
   &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:paddingLeft="0dp"
      android:paddingRight="0dp"
      android:paddingTop="0dp"
      android:paddingBottom="0dp"
      tools:context="com.vroy.trapper.MainMenuActivity"
      android:layout_weight="2"&gt;
  
      &lt;Button
          android:layout_width="0dp"
          android:layout_height="0dp"
          android:text="@string/menu_button_text"
          android:background="@drawable/round_button"
          android:id="@+id/button"
          android:layout_centerVertical="true"
          android:layout_centerHorizontal="true"
          /&gt;
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>I looked at <a href="https://stackoverflow.com/questions/2581481/assign-width-to-half-available-screen-width-declaratively">this</a> question, but even though I assigned a weight to the relative layout itself I could not assign a weight to the button.</p>