JSF Temporary Variable

Is there a way to temporarily save the value of calcuation in a JSF page? I want to do the following without calculating twice:

<h:outputText value="#{complexModel.currencyAmount.currency}">
<h:outputText value="#{complexModel.currencyAmount.amount}">

I've tried using the alias bean but I get an error saying java.lang.IllegalArgumentException - row is unavailabl开发者_C百科e.

e.g.

<t:aliasBean id="bean" alias="#{bean}" value="#{complexModel.currencyAmount}">
  <h:outputText value="#{bean.currency}">
  <h:outputText value="#{bean.amount}">
</t:aliasBean>

Thanks.

---

Two ways (at least):

1. Using lazy-init field of your complexModel. something like:

   private Currency currencyAmount;
   public Currency getCurrencyAmount() {
       if (currencyAmount == null) {
           currencyAmount = calculateCurrencyAmount();
       }
       return currencyAmount;
   }
   

2. Using the JSTL <c:set> tag:

(the namespace first)

xmlns:c="http://java.sun.com/jstl/core"

then

<c:set var="varName" value="#{complexModel.currencyAmount}" />

And then the calculated value will be accessible through #{varName}.

---

In JSF 2.0,you can use <ui:param/> which it's powerful.

<ui:param name="foo" value="#{zhangsan.foo}"/>