显示JSF页面中的HashMap条目的键和值 [英] Display key and value of HashMap entries in JSF page

问题描述

我想在JSF UI中显示 HashMap 键及其关联的值。

我怎样才能做到这一点？如何使用迭代器组件（如< h：datatable> ？？）在JSF页面中迭代 HashMap 只有< c：forEach> 支持


解决方案地图。每次迭代都会提供 Map .Entry 实例返回（就像在普通的Java for 循环中）。

 < c：forEach items =＃{yourBean.map}var =entry> 
< li>密钥：＃{entry.key}，值：＃{entry.value}< / li> 
< / c：forEach> 
  

< h：dataTable> （和< ui：repeat> ）仅支持 List （JSF 2.2将带有 Collection 支持）。您可以将所有密钥复制到单独的 List 中，然后对其进行迭代，然后使用迭代密钥使用 [] $ b

 私人地图< String，String>地图; 
私人列表< String>键列表; 
 
 public void someMethodWhereMapIsCreated（）{
 map = createItSomeHow（）; 
 keyList = new ArrayList< String>（map.keySet（））; 
} 
 
 public Map< String，String> getMap（）{
 return map; 
} 
 
 public List< String> getKeyList（）{
 return keyList; 
 
  





  < h：dataTable value =＃{yourBean.keyList}var =key> 
< h：栏> 
键：＃{key} 
< / h：列> 
< h：栏> 
值：＃{yourBean.map [key]} 
< / h：列> 
< / h：dataTable> 
  

值得注意的是 HashMap 是自然无序。如果您想维护广告订单，请像 List 那样维持广告订单，而改为使用 LinkedHashMap 。

b $ b

I would like to display HashMap keys and its associated value in the JSF UI.

How can I achieve this? How can I iterate over a HashMap in JSF page using some iterator component like <h:datatable>?

解决方案

Only <c:forEach> supports Map. Each iteration gives a Map.Entry instance back (like as in a normal Java for loop).

<c:forEach items="#{yourBean.map}" var="entry">
    <li>Key: #{entry.key}, value: #{entry.value}</li>
</c:forEach>

The <h:dataTable> (and <ui:repeat>) only supports List (JSF 2.2 will come with Collection support). You could copy all keys in a separate List and then iterate over it instead and then use the iterated key to get the associated value using [] in EL.

private Map<String, String> map;
private List<String> keyList;

public void someMethodWhereMapIsCreated() {
    map = createItSomeHow();
    keyList = new ArrayList<String>(map.keySet());
}

public Map<String, String> getMap(){
     return map;
}

public List<String> getKeyList(){
     return keyList;
}

<h:dataTable value="#{yourBean.keyList}" var="key"> 
    <h:column> 
        Key: #{key}
    </h:column> 
    <h:column> 
        Value: #{yourBean.map[key]}
    </h:column> 
</h:dataTable>

Noted should be that a HashMap is by nature unordered. If you would like to maintain insertion order, like as with List, rather use LinkedHashMap instead.

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