title: Action bar not shown in Android Studio
body: <p>I'm using Android Studio for the first time and can't manage to make the <code>ActionBar</code> show when I run the app. Here's what I have so far:</p>
  
  <p>My Activity <em>MainActivity.java</em></p>
  
  <pre><code>package xeniasis.mymarket;
  
  import android.app.Activity;
  import android.os.Bundle;
  import android.view.Menu;
  import android.support.v7.app.ActionBar;
  
  public class MainActivity extends Activity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          getMenuInflater().inflate(R.menu.activity_main, menu);
  
          return super.onCreateOptionsMenu(menu);
      }
  }
  </code></pre>
  
  <p>it's layout <em>activity_main.xml</em> (nothing there)</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: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="xeniasis.mymarket.MainActivity"&gt;&lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>and the menu with one item <em>activity_main.xml</em></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto"
      xmlns:tools="http://schemas.android.com/tools"
      tools:context="xeniasis.mymarket.MainActivity"&gt;
      &lt;item
          android:id="@+id/action_update"
          android:icon="@drawable/ic_action_update"
          android:showAsAction="ifRoom"
          android:title="@string/update_app" /&gt;
  &lt;/menu&gt;
  </code></pre>
  
  <p>Do I need something else in order to show the <code>ActionBar</code>?</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>here is the app theme</p>
  
  <pre><code>&lt;style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar"&gt;
      &lt;!-- Customize your theme here. --&gt;
      &lt;item name="colorPrimary"&gt;@color/colorPrimary&lt;/item&gt;
      &lt;item name="colorPrimaryDark"&gt;@color/colorPrimaryDark&lt;/item&gt;
      &lt;item name="colorAccent"&gt;@color/colorAccent&lt;/item&gt;
  &lt;/style&gt;
  </code></pre>