How can I change the field in the list of objects using RXJava / Android

Question

I have a list of myPersonList and I want to populate the Name and City of each item. I have already filled in the identifier. I could create a foreach and call FillPersonData, but how can I do this with Observables? I know there is something with Map () and FlatMap () ... but I don't understand it

class Person{
   int id;
   String name;
   String city;
}

List<Person> myPersonList;

what should I do to get an observable list where Person data is filled with this function:

class PersonUtil{

      public Person FillPersonData(Person person){
          ... do something to fill the Person Data...
      }
}

Update:

Sorry, my flaw: I did not say that I also need an Observable to subscribe to it. And not the Person class has a function called fillPersonData () ... let me say that I have something like PersonUtil ...

I need this to get it back:

Observable<List<Person>> myObservable  = ...the Magic Code :-)

Update 2:

frhack, . , Android Studio Lambdas Lambdas:

 Observable<Person> observable =  Observable.from(personList)
            .filter(new Func1<Person, Boolean>() {

                @Override
                public Boolean call(Person person) {
                    PersonUtil.FillMailData(person);
                    return true;
                }

            });

, ... ... , Update2!

Answer 1

List<Person> personList = new ArrayList<Person>();
// populate personList
Observable.from(personList).forEach((person)-> {
        person.setName(name);
        person.setCity(city);
});

:

List<Person> personList = new ArrayList<Person>();
// populate personList
Observable.from(personList).forEach((person)-> p.fillPersonData() );

:

List<Person> personList = new ArrayList<Person>();
// populate personList
Observable<Person> observable =  Observable.from(personList)
   .filter((person) -> {
            person.setName(name);
           //PersonUtil.fillPersonData(person)     
            return true;
        });
 observable.forEach((pp)->System.out.println(pp));