如何以编程方式将oldValue设置为selectOneMenu

Question

Java / PrimeFaces 3.5

我想回滚primeFaces selectOneMenu Old Value并重新加载它在屏幕上更新组件。

1. selectOneMenu加载了FIRST，SECOND，THIRD值，默认值设置为FIRST

2. 如果我将selectOneMenu值从FIRST更改为THIRD，我想再次将其设置为FIRST。

   <p:selectOneMenu id="statusProposta"
      value="#{propostaBean.propostaComercial.proposta_Status}"
        items="#{propostaBean.statusProposta}"
        valueChangeListener="#{propostaBean.regraStatusProposta}" >
        <p:ajax  event="change"  
          process="statusProposta" update="statusProposta" />
        <f:selectItem itemLabel="" itemValue="" />
        <f:selectItems value="#{propostaBean.statusProposta}" />
   </p:selectOneMenu>
   

StatusProposta：

public enum StatusProposta {FIRST，SECOND和THIRD .....

Bean：

public void regraStatusProposta(ValueChangeEvent ev){
   **I dont know how to set the old value and update it in screen.**
   ...

Answer 1

public void regraStatusProposta(ValueChangeEvent ev){    
//get old value first 
Object oldValue=ev.getOldValue();    
}

More on ValueChangeEvent API

Answer 2

http://forum.primefaces.org/viewtopic.php?f=3&t=36447

resetinput

博客文章：重置JSF 2.2的值

霍华德在primefaces论坛上发表了

http://www.primefaces.org/showcase/ui/resetInput.jsf

public void reset() {  
    RequestContext.getCurrentInstance().reset("form:panel");  
}