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marți, 13 octombrie 2015

[OmniFaces utilities (2.0)] Convert a Map<K, V> to a List<Map.Entry<K, V>>


[OmniFaces utilities] The mapToList() function converts a Map<K, V> to a List<Map.Entry<K, V>>. Useful when you want to iterate over a Map in for example <ui:repeat>. Each of the entries has the usual getKey() and getValue() methods.

Function:
Usage:

The of:mapToList() is very useful for JSF 2.2/2.0/2.1 where <h:dataTable> (and <ui:repeat>) doesn't support Map directly. For example, via this method you can easily use #{fooBean.map} in <h:dataTable>:

HashMap<String, Players> dataHashMap = new HashMap<>();
TreeMap<String, Players> dataTreeMap = new TreeMap<>();
LinkedHashMap<String, Players> dataLinkedHashMap = new LinkedHashMap<>();  

Now, for JSF 2.2/2.1/2.0, you can do this:

<h:dataTable value="#{of:mapToList(playersBean.dataHashMap)}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

<h:dataTable value="#{of:mapToList(playersBean.dataTreeMap)}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

<h:dataTable value="#{of:mapToList(playersBean.dataLinkedHashMap)}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

However, starting with JSF 2.2, UIData (e.g.  <h:dataTable>) support Set directly, so you don't need of:mapToList() if you prefer entrySet() (you may want to consider keySet() and values() also):

<h:dataTable value="#{playersBean.dataHashMap.entrySet()}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

<h:dataTable value="#{playersBean.dataTreeMap.entrySet()}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

<h:dataTable value="#{playersBean.dataLinkedHashMap.entrySet()}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

When Set is not directly supported, but, if EL 2.2 is available, then you can use toArray() method, so you don't need of:mapToList():

<h:dataTable value="#{playersBean.dataHashMap.entrySet().toArray()}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

<h:dataTable value="#{playersBean.dataTreeMap.entrySet().toArray()}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

<h:dataTable value="#{playersBean.dataLinkedHashMap.entrySet().toArray()}" var="t">
 #{t.key} #{t.value}
</h:dataTable>

Well, speaking about <ui:repeat>, you should know that Map is not supported directly in JSF 2.2/2.1/2.0. In such cases, you can use of:mapToList():

<ui:repeat value="#{of:mapToList(playersBean.dataHashMap)}" var="t">
 <h:outputText value="key:#{t.key} value:#{t.value}" />
</ui:repeat>

<ui:repeat value="#{of:mapToList(playersBean.dataTreeMap)}" var="t">
 <h:outputText value="key:#{t.key} value:#{t.value}" />
</ui:repeat>

<ui:repeat value="#{of:mapToList(playersBean.dataLinkedHashMap)}" var="t">
 <h:outputText value="key:#{t.key} value:#{t.value}" />
</ui:repeat>

Starting with JSF 2.2, UIData (e.g.  <h:dataTable>) support Set directly, but <ui:repeat> doesn't! So, if EL 2.2 is available, you can use toArray() method. Below, you can see four approaches exemplified on dataHashMap:

<ui:repeat value="#{playersBean.dataHashMap.entrySet().toArray()}" var="t">
 <h:outputText value="key:#{t.key} value:#{t.value}" />
</ui:repeat>

<ui:repeat value="#{playersBean.dataHashMap.keySet().toArray()}" var="t">
 <h:outputText value="key:#{t} value:#{playersBean.dataHashMap.get(t)}" />
</ui:repeat>

<ui:repeat value="#{playersBean.dataHashMap.values().toArray()}" var="t">
 <h:outputText value="#{t}" />
</ui:repeat>

<ui:repeat value="#{playersBean.dataHashMap.entrySet()}" var="t">
 <ui:repeat value="#{t.toArray()}" var="q">
  <h:outputText value="key:#{q.key} value:#{q.value}" />
 </ui:repeat>

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