How to create different objects from a List of Strings?

byMR

October 12, 2022

I have a file with a various figures like this:

SQUARE;10

SQUARE;20

RECTANGLE;10;30

CIRCLE;10

After adding the lines to the String List, I would like it to create all the objects after one run through the list. how to do it when, for example, a rectangle has two parameters and the rest only one?

So far this is my code which works but it is buggy, because for each type of figure I have to go through the list again, I also can’t use switch for this task.

    BufferedReader br = new BufferedReader(new FileReader("figury.txt"));
    List<List<String>> list1 = new ArrayList<>();
    String s;
    while ((s = br.readLine()) != null) {
        List<String> list = Arrays.asList(s.split(";"));
        list1.add(list);

    }
    list1.stream().filter(k -> k.contains("SQUARE")).forEach(i -> new Square(Integer.parseInt(i.get(1))));
    list1.stream().filter(k -> k.contains("CIRCLE")).forEach(i -> new Circle(Integer.parseInt(i.get(1))));
    list1.stream().filter(k -> k.contains("RECTANGLE")).forEach(i -> new Rectangle(Integer.parseInt(i.get(1)), Integer.parseInt(i.get(2))));

All figures are subClasses of abstract class Figure

>Solution :

Try this

        Map<String, Function<List<String>, Figure>> converters = new HashMap<>();
        converters.put("SQUARE", l -> new Square(Integer.parseInt(l.get(1))));
        // Repeat for each shape

        List<Figure> list = list1.stream().map(l -> converters.get(l.get(0)).apply(l))
                .collect(Collectors.toList());