如何从项目标签中的Map 获取值

Below is the jsf code

下面是jsf代码

  <h:selectOneMenu>
  <f:selectItems value="#{bean.mapObject}"var="entity" 
  itemValue="#{entity.key}" itemLabel="#{entity.value.code}"/> 
  </h:selectOneMenu>

Backing bean has map defined as

Backing bean将map定义为

 private Map<TestClass, Object> mapObject;

TestClass has two variables and getters/setters

TestClass有两个变量和getter / setter

 String code;
 String name;

Issue I am having is : On JSF, on Selectonemenu, for itemLabel i would like to display the TestClass String value i.e code should be displayed.

我遇到的问题是:在JSF上,在Selectonemenu上,对于itemLabel,我想显示TestClass字符串值,即应显示代码。

Presently on SelectOneMenu on UI, I am getting

目前在UI上的SelectOneMenu上,我得到了

 TestClass[code=t,name=anu] on the drop down, instead i want code value i..e 't'

Please let me know how to acheive this.

请让我知道如何实现这一目标。

2 个解决方案

#1

The <f:selectItems var> should in case of maps specify the Map.Entry. The <f:selectItems value> should therefore specify Collection<Map.Entry>. This is not natively recognized yet when you just specify a Map (will come in JSF 2.3).

应该在map的情况下指定Map.Entry。因此, 应指定Collection 。当您只是指定一个Map(将在JSF 2.3中提供)时,这本身并未得到认可。值>

You basically need to explicitly set the value to Map#entrySet() as below in case you intend to use map key as item value and ma:

您基本上需要将值显式设置为Map#entrySet(),如果您打算使用map键作为项值和ma:

<h:selectOneMenu>
    <f:selectItems value="#{bean.mapObject.entrySet()}"var="entry" 
        itemValue="#{...}" itemLabel="#{...}" /> 
</h:selectOneMenu>

The Map.Entry object has getKey() and getValue() methods which return respectively the map entry's key and map entry's value, which are in your case respectively TestClass and Object. You seem to want to display the code property of TestClass as item label. So, this should do:

Map.Entry对象具有getKey()和getValue()方法,它们分别返回映射条目的键和映射条目的值,在您的情况下分别为TestClass和Object。您似乎想要将TestClass的代码属性显示为项标签。所以,这应该做:

<h:selectOneMenu>
    <f:selectItems value="#{bean.mapObject.entrySet()}"var="entry" 
        itemValue="#{...}" itemLabel="#{entry.key.code}" /> 
</h:selectOneMenu>

You're not terribly clear on what exactly you'd like to use as item value, so I've left it open.

你不清楚你想用什么作为物品价值,所以我把它打开了。

#2

You need to change the itemlabel attribute, (with current value entity.value.code). It should be replaced by entity.key.code ?

您需要更改itemlabel属性(使用当前值entity.value.code)。它应该被entity.key.code取代?

Also the value needs to call the method .entrySet , because the map in itself is not a collection.

此值还需要调用方法.entrySet,因为映射本身不是集合。

<h:selectOneMenu>
  <f:selectItems value="#{bean.mapObject.entrySet()}" var="entry" 
     itemValue="#{entry.key}" itemLabel="#{entry.key.code}"/> 
</h:selectOneMenu>

Alternatively, since it's the key you want, you could iterate the keys immediately.

或者,因为它是您想要的密钥,您可以立即迭代密钥。

<h:selectOneMenu>
  <f:selectItems value="#{bean.mapObject.keySet()}" var="key" 
     itemValue="#{key}" itemLabel="#{key.code}"/> 
</h:selectOneMenu>

#1