title: javafx fxml ComboBox Error
body: <p>Im trying to add a String to a javafx comboBox but i keep getting the above error :/
  <br></p>
  
  <pre><code>no suitable method found for add(String)
  method Collection.add(CAP#1) is not applicable
    (argument mismatch; String cannot be converted to CAP#1)
  method List.add(CAP#1) is not applicable
    (argument mismatch; String cannot be converted to CAP#1)
     where CAP#1 is a fresh type-variable:
    CAP#1 extends Object from capture of ?
  </code></pre>
  
  <h1>CODE</h1>
  
  <pre><code>room_id.getItems().add("Hello");
  </code></pre>
  
  <h1>FXML</h1>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  
  &lt;?import java.lang.*?&gt;
  &lt;?import java.util.*?&gt;
  &lt;?import javafx.scene.*?&gt;
  &lt;?import javafx.scene.control.*?&gt;
  &lt;?import javafx.scene.layout.*?&gt;
  
  
  &lt;AnchorPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.AutoMaven.ui.controller.ComboTestController"&gt;
     &lt;children&gt;
        &lt;ComboBox fx:id="room_id" layoutX="170.0" layoutY="185.0" prefHeight="31.0" prefWidth="260.0" /&gt;
     &lt;/children&gt;
  &lt;/AnchorPane&gt;
  </code></pre>
  
  <h1>UPDATE</h1>
  
  <p>After using a list, i get</p>
  
  <p>incompatible types: String cannot be converted to CAP#1 <br>
    where CAP#1 is a fresh type-variable: <br>
      CAP#1 extends Object from capture of ?</p>
  
  <pre><code>ObservableList&lt;String&gt; list=FXCollections.observableArrayList("1","2","3","4");
  
  room_id.setItems(list);
  </code></pre>