Android - AdView missing required XML attribute 'adSize'

To make it work with Google Play services use:

xmlns:ads="http://schemas.android.com/apk/res-auto"

<com.google.android.gms.ads.NativeExpressAdView   

     android:id="@+id/adView"   

     android:layout_width="wrap_content"  

      android:layout_height="wrap_content" 

       ads:adSize="FULL_WIDTHx300" 

       ads:adUnitId="ca-app-pub-3940256099942544/2177258514"
        android:layout_gravity="center_horizontal"        >
</com.google.android.gms.ads.NativeExpressAdView>

mainActivity

MobileAds.initialize(this,"ca-app-pub-2894281250061472~5038272149");
 NativeExpressAdView adView = 
(NativeExpressAdView)findViewById(R.id.adView);

 AdRequest request = new AdRequest.Builder()
         .build(); adView.loadAd(request);

Using the Android Toolbar (ActionBar) - Tutorial

http://www.vogella.com/tutorials/AndroidActionBar/article.html

Using the App Toolbar

https://guides.codepath.com/android/Using-the-App-Toolbar

Toolbar vs ActionBar

randome sql

SELECT * FROM `post_table` ORDER BY RAND() LIMIT 1;