a list of list value populated in struts2 iterator - list

Question

For my case, it is a little bit trickier. I just have another list in person object, it is called state. like below:
public class People {
private int id;
private String name;
private List<State> states;
// Plus setters/getters
}
public class State {
private int id;
private String stateAbbr;
private String stateName;
public State (String stateAbbr, String stateName) {
this.stateAbbr = stateAbbr;
this.stateName = stateName;
}
// Plus setters/getters
}
Action class:
public class PersonAction extends ActionSupport {
private List<People> peopleList;
public List<People> getPeopleList() {
return peopleList;
}
public void setPeopleList(List<People> peopleList) {
this.peopleList = peopleList;
}
//Initial Load method
#Override
public String execute() {
peopleList = new ArrayList<People>();
int alpha = 65;
for(int i = 0; i < 3 ; i++) {
People people = new People();
people.setId(i);
people.setName(String.valueOf((char)alpha++));
peopleList.add(people);
}
for (People people : peopleList){
State state = new State("BC", "BritishColumbia");
List<State> states = new ArrayList<State>();
states.add(state);
state = new State("AC", "AppleColumbia");
states.add(state);
people.setStates(states);
}
return SUCCESS;
}
//Function that handles the form submit
public String updatePerson() {
for(People people : peopleList) {
System.out.println(people.getId() + ":" + people.getName());
}
return SUCCESS;
}
}
JSP page
<s:form action="doUpdate">
<s:iterator value="peopleList" status="stat" var="people">
<s:textfield value="%{#people.name}"
name="peopleList[%{#stat.index}].name" />
<s:iterator value="states" status="stateStatus" var="personState">
<s:textfield value="%{#personState.stateAbbr}"
name="peopleList[%{#stat.index}].states[%{#stateStatus.index}].stateAbbr" label="Abbr State" />
<br />
</s:iterator>
</s:iterator>
<s:submit value="Submit" />
</s:form>
When I submit this page, I got states is [null] in person, why?

Answer 1

Answer for the new question:
If your State class doesn't have a default constructor, S2/OGNL will not be able to instantiate an empty version of the class.
Provide a default (no-argument) constructor, and the person's states list will be populated.
(Too bad both answers can't be accepted ;)

Answer 2

The state property is a property of a specific person. In this case, you need to "connect" the state to persons[%{#stat.index}], so:
<s:textfield ...
name="persons[%{#stat.index}].states[%{#stateStatus.index}]" .../>
The iterator status variable has an index property that avoids the math you're doing on the IteratorStatus (docs) instance:
<s:textfield ... name="persons[%{#stat.index}].name" />
Also, depending on which version of S2 you're using, you may not need the # character.