title: App Bar is not showing in Android Studio but showing on an actual android device
body: <p>I have already checked similar problems like mine but none of it helped. I also checked my previous project with the same AppTheme, they are the same but I have noticed everytime I create a new android project, the App bar is not showing even after several "Rebuild Project".</p>
  
  <p>This is what my styles.xml shows</p>
  
  <pre><code>&lt;resources&gt;
  
      &lt;!-- Base application theme. --&gt;
      &lt;style name="AppTheme" parent="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;
  
  &lt;/resources&gt;
  </code></pre>
  
  <p>This is what my AndroidManifest.xml shows</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.example.mycontact"&gt;
  
      &lt;application
          android:allowBackup="true"
          android:icon="@mipmap/ic_launcher"
          android:label="@string/app_name"
          android:roundIcon="@mipmap/ic_launcher_round"
          android:supportsRtl="true"
          android:theme="@style/AppTheme"&gt;
          &lt;activity android:name=".MainActivity"&gt;
              &lt;intent-filter&gt;
                  &lt;action android:name="android.intent.action.MAIN" /&gt;
  
                  &lt;category android:name="android.intent.category.LAUNCHER" /&gt;
              &lt;/intent-filter&gt;
          &lt;/activity&gt;
      &lt;/application&gt;
  
  &lt;/manifest&gt;
  </code></pre>
  
  <p>My MainActivity.java (Haven't put code yet)</p>
  
  <pre><code>package com.example.mycontact;
  
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  
  public class MainActivity extends AppCompatActivity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
      }
  }
  </code></pre>
  
  <p>And my activity_main.xml </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout 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"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".MainActivity"
      android:orientation="vertical"&gt;
  
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>I have also tried changing the layout from ContraintLayout, RelativeLayout but nothing has changed. Zooming in and zooming out the layout doesn't change at all. Here is a snapchat.. Thank you for your help.</p>
  
  <p><a href="https://i.stack.imgur.com/7BwUO.png" rel="nofollow noreferrer">activity_main.xml page</a></p>