title: ListView OnItemLongClick ActionMode Error
body: <p>I have a programm with a simple <code>ListView</code> and set an <code>OnItemLongClickListener</code> on it. All fine, Android Studio doesn't show any mistake. But when I <code>longclick</code> in the app, the app stopped and Android Studio showed a Runtime Error:</p>
  
  <blockquote>
    <p>java.lang.NullPointerException: Attempt to invoke interface method
    'boolean android.view.ActionMode$Callback.onCreateActionMode
    (anddroid.view.ActionMode, android.view.Menu)' on a null object
    reference</p>
  </blockquote>
  
  <p>What does <code>ListView</code> and <code>OnItemLongClickListener</code> have to do with ActionMode?
  And how can I fix it?</p>