primefaces 通过selectOneMenu更新显示隐藏区域

最重要的是update的区域要指定整个panel，而不是想更新的那个组件
 
<h:form id="frm">
    <h:panelGrid id="panelgrid">
        <p:panel id="panel" >
        <h:outputLabel value="Name: " for="name" />
            <p:inputText id="name" value="#{userBean.name}" immediate="true" onkeypress="#{userBean.showName}">
 
                <p:ajax event="change" update="frm:panelgrid" listener="#{userBean.inputcangeeListener}" />
            </p:inputText>
        </p:panel>
 
 
            <p:panel id="p2" rendered="#{userBean.displayName}">
                <p:selectOneRadio id="city" value="#{userBean.city}" layout="grid" columns="3">
                    <f:selectItems value="#{userBean.cities}" var="c" itemLabel="#{city}" itemValue="#{city}" />
                </p:selectOneRadio>
            </p:panel>
 
        </h:panelGrid>
    </h:form>

And my managed bean looks like-

    @PostConstruct
    public void init() {
        displayName = false;
    }
 
    public boolean isShowName(){
        return displayName;
    }
 
    public void inputcangeeListener(javax.faces.event.AjaxBehaviorEvent changeEvent){
        setDisplayName(true);
        cities = new ArrayList<>();
        cities.add("pune");
        cities.add("KOL");
 
    }