title: find in MongoCollection<Document>
body: <p>I have a <code>MongoCollection&lt;Document&gt;</code> in which I assign a collection.
  I'm trying to find a user by his id.</p>
  
  <pre><code>user = (Document) usersCollection.find(new Document("_id", username));
  </code></pre>
  
  <p>with that I'm getting an error </p>
  
  <blockquote>
    <p>java.lang.ClassCastException: com.mongodb.FindIterableImpl cannot be
    cast to org.bson.Document</p>
  </blockquote>
  
  <p>When I try </p>
  
  <pre><code>    BasicDBObject query = new BasicDBObject(); 
      BasicDBObject fields = new BasicDBObject("_id", username);
      usersCollection.find(query, fields);
  </code></pre>
  
  <p>I'm getting an error </p>
  
  <blockquote>
    <p>The method find(Bson, Class) in the type MongoCollection is not applicable for the arguments (BasicDBObject, BasicDBObject)</p>
  </blockquote>