Functional Programing; using streams to create a set/ list of objects in java

Question

the object of this specific function is to create a list of (competitor objects ) Using 2 lists containing time and names.

note that this is a trail to convert from object oriented to functional programing , so its actually a record rather than an object.

my initial trial using a sort of recursion

public static List<Competitors> makeObjects(int[] time, String[] name){
        if (counter > name.length){
            return racers;
        }else{
            Competitors racer= new Competitors(name[counter],backToTime(time[counter]));
            racers.add(racer);
            return makeObjects(++counter,racers,time,name);
        }

and my try after discovering i can use streams

public static List<Competitors> makeObjects(int[] time, String[] name){
        List<Competitors> racers = new ArrayList<Competitors>();
        IntStream.range(0,time.length).mapToObj(i-> ).collect(new Competitors(name[i] ,backToTime(time[i])))
    }

Answer 1

Your second approach, makeObjects(), is the functional approach.

Where you go wrong is that you are creating the Competitor objects in the wrong place; you map each i to a new Competitor. Then in the collect() call, you specify what type of collection. In your case, it would be Collectors.toList() or Collectors.toSet(). There is no need to create an ArrayList; just assign the IntStream... to List<Competitor> racers.

Note that you should probably guard this method by first asserting that the arrays are the same length.

Also note that your class should be named Competitor, not Competitors; and makeObjects would be more descriptive as createCompetitorsList.