Access object attribute when object name is variable in struts2

Question

I'm having some trouble accessing a specific object attribute of a list of objects when the attribute name is a variable.

This is an example, where users is a list of User and userAttributeList is a list of String which contains the name of user attribute.

<%
    .......
    ActionContext.getContext().put("userAttributeList", request.getAttribute("userAttributeList"));


%>

<s:iterator value="users">
    <s:iterator value="%{userAttributeList}" var="userAttribute">
    ...  <s:property value="%{#userAttribute}" />
    </s:iterator>
</s:iterator>

In this case, the property tag not return value of attribute like John, 20-05-1990 and so on , but return the name of attribute like username, birthDate and so on.

    public class UserAction extends ActionSupport {

        @Override
        public String execute()
                throws Exception {
             HttpServletRequest request = ServletActionContext.getRequest();

                   ArrayList userAttributeList= new ArrayList();

                  // some logic implementation and populate the `userAttributeList`(username, birthDate, password etc) 

                  request.setAttribute(userAttributeList, userAttributeList);


                  return SUCCESS;

        }
}

The userAttributeList ArrayList contain the name of attribute of an User. This ArrayList is used to simplify the implementation and create a dynamicaly solution for this:

<s:iterator value="users">
         <s:property value="%{username}" />
         <s:property value="%{birthDate}" />
         <s:property value="%{password}" />
         ....
   </s:iterator>

Answer 1

You have populated only names of attributes of the user object. But didn't put values. Instead of ArrayList you should use a Map if you want to have dynamic fields of the user object.

Map<String, Object> userAttributeMap= new HashMap<>();
userAttributeMap.put("username", "John");
userAttributeMap.put("birthDate", "20-05-1990");
....

Now in the JSP you should evaluate map keys using OGNL

<s:iterator value="%{userAttributeMap}" var="userAttribute">
...  <s:property value="%{#userAttribute['username']}" />
     <s:property value="%{#userAttribute['birthDate']}" />
</s:iterator>