Calculate values on value insert - jsf

Question

I want to create very simple JSF web page which I would like to use for price calculation:
<h:form>
<h:outputText value="Number of Computers"/>
<h:panelGroup layout="block" id="desktopClients_select" style="padding-top: 3px;" styleClass="text">
<h:inputText id="desktopClients" value="#{pricingCalculator.computers}">
<f:ajax event="change" render="#form" listener="#{pricingCalculator.calculateTotalPrice}"/>
</h:inputText>
</h:panelGroup>
<h:outputText value="Email support incidents"/>
<h:panelGroup layout="block" id="email_support_incidents" style="padding-top: 3px;" styleClass="text">
<h:inputText id="email_support_incidents_text" value="#{pricingCalculator.emailSupportIncidents}">
<f:ajax event="change" render="#form" listener="#{pricingCalculator.calculateTotalPrice}"/>
</h:inputText>
</h:panelGroup>
<h:outputText value="Phone support incidents"/>
<h:panelGroup layout="block" id="phone_support_incidents" style="padding-top: 3px;" styleClass="text">
<h:inputText id="phone_support_incidents_text" value="#{pricingCalculator.phoneSupportIncidents}">
<f:validateLongRange minimum="1" maximum="150" />
<f:ajax event="change" render="#form" listener="#{pricingCalculator.calculateTotalPrice}"/>
</h:inputText>
</h:panelGroup>
<h:outputText value="Total price"/>
<h:panelGroup layout="block" id="total_price" style="padding-top: 3px;" styleClass="text">
<h:outputText value="#{pricingCalculator.calculateTotalPrice}"/>
</h:panelGroup>
</h:panelGrid>
</h:form>
Bean:
#Named
#ViewScoped
public class PricingCalculator implements Serializable
{
private int computers;
private float emailSupportIncidents;
private float phoneSupportIncidents;
private float totalPrice;
// Prices for each component and service
private final float computers_price = 299;
private final float emailSupportIncidents_price = 300;
private final float phoneSupportIncidents_price = 150;
public String getCalculateTotalPrice()
{
totalPrice = (computers_price * computers)
+ (emailSupportIncidents_price * emailSupportIncidents)
+ (phoneSupportIncidents_price * phoneSupportIncidents);
String result = Float.toString(totalPrice);
return result;
}
public int getComputers()
{
return computers;
}
public void setComputers(int computers)
{
this.computers = computers;
}
public float getEmailSupportIncidents()
{
return emailSupportIncidents;
}
public void setEmailSupportIncidents(float emailSupportIncidents)
{
this.emailSupportIncidents = emailSupportIncidents;
}
public float getPhoneSupportIncidents()
{
return phoneSupportIncidents;
}
public void setPhoneSupportIncidents(float phoneSupportIncidents)
{
this.phoneSupportIncidents = phoneSupportIncidents;
}
public float getTotalPrice()
{
return totalPrice;
}
public void setTotalPrice(float totalPrice)
{
this.totalPrice = totalPrice;
}
}
When I insert some value into the input fields I would like to recalculate the total price. I have now two issues: I get exception serverError: class javax.el.MethodNotFoundException /pricing_calculator.xhtml #115,136 listener="#{pricingCalculator.calculateTotalPrice}": Method not found: com.web.common.PricingCalculator#22939533.calculateTotalPrice(javax.faces.event.AjaxBehaviorEvent)
and when I insert new value previous one is set to zero. It's not remembered properly.

Answer 1

#BalusC has already given you the answer, but to be more explicit, here's a quote from Oracle's Java EE 6 tutorial (which you should read) about Method Expressions:
Method expressions can be used only in tag attributes and only in the
following ways:
With a single expression construct, where bean refers to a JavaBeans component and method refers to a method of the JavaBeans
component:
<some:tag value="#{bean.method}"/>
[...]
That said, rename getCalculateTotalPrice to calculateTotalPrice
Edit: There's also an inconsistency between the expected signatures of the following method calls:
<f:ajax listener="#{pricingCalculator.calculateTotalPrice} .../>
which expects a MethodExpression refering to a calculateTotalPrice(javax.faces.event.AjaxBehaviorEvent) method as clearly stated by the javax.el.MethodNotFoundException
and
<h:outputText value="#{pricingCalculator.calculateTotalPrice}"/> which expects a java.lang.String that can refer to a bean property, or the return value of a method call.
Here, the <h:outputText> value is probably meant to be set to the totalPrice property, so it should be: <h:outputText value="#{pricingCalculator.totalPrice}"/>