Inside an Activity Class, We Want to Create an AdView

Essay

Inside an Activity class, we want to create an AdView, set its size using the SMART_BANNER constant of the AdSize class, and set its ad unit id to ca-app-pub-xyz. Write the code for it.
The AdView constructor, setAdSize, and setAdUnitId methods of the AdView class have the following APIs:
public AdView( Context context )
public void setAdSize( AdSize adSize )
public void setAdUnitId( String adUnitId )