How to retrieve checkbox values in Struts 2 action class ?

Question

I have dynamic number of checkboxes in jsp page as given below.

<s:iterator value="details"  status="stat">
         <s:checkbox name="checkbox"  theme="simple" />
         <s:hidden name="hidden" value="%{top}" /> 
</s:iterator>

Let's say 4 checkboxes.

and setter in action class is

public void setCheckbox(boolean s[])
{
    System.out.println(s.length);
}

If I don't select any checkbox, s.length is zero. If I select 3rd checkbox, s.lenght is 1 and it is initializing s[0] with true. But problem is here how can I find whether 3rd checkbox is selected or another checkbox is selected.

I thought that setter would initialize s[]={false,false,true,false}, if I select third checkbox. But it is initializing s[]={true}.

Corresponding hidden values of those selected boxes are required to perform required action in database. But for that I need to find select checkboxes.
Please suggest me any solution.

Answer 1

Because your checkboxes are all named the same (checkbox), Struts2 is just passing the following:

checkbox=true&checkbox=true&checkbox=true

Does that mean that you omitted the second, third, or fourth checkbox?

What you actually want is not an array of booleans, but a map of Integer to Boolean. Here's an example:

Example Action

public class MyAction extends ActionSupport {
  private Map<Integer, Boolean> checkboxes;

  ...

  public Map<Integer, Boolean> getCheckboxes() {
    return checkboxes;
  }

  public void setCheckboxes(Map<Integer, Boolean> checkboxes) {
    this.checkboxes = checkboxes;
  }
}

Example JSP

<s:iterator value="details" status="stat">
  <%-- this outputs checkboxes[0], checkboxes[1], etc. --%>
  <s:checkbox name="checkboxes[%{#stat.index}]"  theme="simple" />
</s:iterator>

Example Result

• 0 -> true
• 1 -> false
• 2 -> true
• 3 -> true

Answer 2

Actually I use Struts 2 3.8 and WebSphere 7.0 and Map works for rendering the check boxes, but not working when these check boxes post back. The Boolean class is rendered correctly, but during the post back in Struts 2, it becomes ognl.NoConversionPossible and ends up with No result defined for action CLASS ...and result input error.
I replaced Boolean with String class, i.e.

maps.put(new Integer(0), new String("true")); 

and it works for me.