Change a FormElement’s information by changing directly its formData keyVals’s list jsoup

I’m trying to fill out a form using Jsoup library’s class FormElement. My problem is that it doesn’t change the values in the KeyVals it submits. I have found on Jsoup documentation that they have done this on purpose:

public List<Connection.KeyVal> formData()
Get the data that this form submits. The returned list is a copy of the data, and changes to the contents of the list will not be reflected in the DOM.
Returns:
a list of key vals

Can anyone tell me how I can change the KeyVals within a list of key vals retrieved from the method formData available for FormElement. By now this is what I’m doing and getting, so that you may understand me better:

FormElement form = (FormElement) document.select(form#formulaire).first();
System.out.println(form.formData().get(4).value()); //printing the value of  KeyVal #4 
form.formData().get(4).value("value changed");//changing its value
System.out.println(form.formData().get(4).value());//printing again its value which must be different
Result: 
Old value
Old value

Please, notice that I know that I can do this myself by changing the value on every element inside the DOM. However, I don’t think this way is neither the cleanest nor the fastest. So is there any way to do this by changing the values directly in the form data?

Solution

Each call to the method formData() creates a new list of results by walking the DOM and pulling the values out. So, just don't keep re-evaluating that method. Instead, take a reference and set the values from that. E.g.:

FormElement form = (FormElement) document.select(form#formulaire).first();
List<Connection.KeyVal> formData = form.formData();
System.out.println(formData.get(4).value()); //printing the value of  KeyVal #4 
form.formData().get(4).value("value changed");//changing its value
System.out.println(form.formData().get(4).value());//printing again its value which must be different

Result: 
Old value
value changed

You can then pass the same form data into a new post/get request.

I actually did expect people just to update the DOM. It's pretty efficient and there's no real different in efficiency in changing the value of something in a formdata object vs changing its value in the DOM, they're all backed by the same kind of hashes / arrays. And there's no HTML parsing or anything.