struts2 - optiontransferselect - pass list of integers to the action - struts2

Question

I have an optiontransferselect in a form but i dont know how to get the selected items in the rightlist back in my action.
I need to get a list with all the visited countries' ids. i tried in my action List (Integer) countriesVisitedId; but it returns nullPointerException. then i tried Integer id but it returns null.
this is what i have:
s:optiontransferselect
label="Select visited countries"
name="countriesNotVisitedId"
leftTitle="Not visited countries"
rightTitle="Visited Countries"
list="%{countriesNotVisited}"
listKey="id"
listValue="name"
headerKey="countryNotVisitedId"
headerValue="--- Please Select ---"
doubleName="countriesVisitedId"
doubleList="%{countriesVisited}"
doubleHeaderKey="countryVisitedId"
doubleHeaderValue="--- Please Select ---"
doubleListKey="id"
doubleListValue="name" />
how can I get the list with the Integers ids of the visited countries in my action?

Answer 1

I was banging my head on the wall wondering what I was doing wrong. It is pretty simple
doubleName="fields" is the tag field that is returned
public void setFields(String fields) { this is what needs to be in your action class.
The thing that I didn't realise is the elements need to be selected in order to be sent back. Or simple use ajax with in your header

Answer 2

Here's what I tried, it works fine.
Step 1: JSP to select the country from the left hand side into right hand.
<s:optiontransferselect
label="Favourite Characters"
name="leftSide"
id="left"
leftTitle="Left Title"
rightTitle="Right Title"
list="%{countriesNotVisited)"
multiple="true"
headerKey="headerKey"
doubleList="{}"
doubleId="right"
doubleName="rightSide"
doubleHeaderKey="doubleHeaderKey"
doubleMultiple="true" />
Step 2: Javascript code to auto select all data from the right hand side.
function selectall()
{
var list = document.getElementById("right");
for (var i = 0; i < list.options.length; i++)
{
alert(list.options[i].value)
list.options[i].selected = true;
}
var form = document.getElementById("right");
form.submit();
return true;
}
Step 3: call this function on submit, from the JSP side.
<s:submit id="submitid" value="Submit" action="insert" onclick="selectall()"/>
Step 4: In the action, make the getters and setters of object names of the left and right sides take strings and not string arrays.
private String leftSide;
private String rightSide;
public String getLeftSide() {
return leftSide;
}
public String getRightSide() {
return rightSide;
}
public void setRightSide(String rightSide) {
this.rightSide = rightSide;
}
public void setLeftSide(String leftSide) {
this.leftSide = leftSide;
}
Now if you try to print a value in the action, you will get values:
System.out.println("right side list " + ad.getRightSide());

Answer 3

In your action:
public void setCountriesVisitedId(String[] countriesVisitedId) {
this.countriesVisitedId = countriesVisitedId;
}