我试图将字符串添加到javafx comboBox，但我不断收到上述错误：/

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 ?

码

room_id.getItems().add("Hello");

XML文件

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>


<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">
   <children>
      <ComboBox fx:id="room_id" layoutX="170.0" layoutY="185.0" prefHeight="31.0" prefWidth="260.0" />
   </children>
</AnchorPane>

更新

使用列表后，我得到

不兼容的类型：不能将字符串转换为CAP＃1
，其中CAP＃1是新的类型变量：
CAP＃1扩展了对象的捕获？

ObservableList<String> list=FXCollections.observableArrayList("1","2","3","4");

room_id.setItems(list);