title: How to change AppCompat v21 toolbar theme programmatically?
body: <p>This is my toolbar xml </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
  
      android:id="@+id/toolbar"
      android:layout_width="match_parent"
      app:contentInsetEnd="0dp"
      app:contentInsetStart="0dp"
      android:layout_height="@dimen/toolbar_height"
      app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
      app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
      android:background="@color/primary_color"&gt;
  
  
  
  &lt;/android.support.v7.widget.Toolbar&gt;
  </code></pre>
  
  <p>I want to change  <strong>app:theme</strong>  programmatically.
  How do i do this?</p>