Person -----

 private void setMoney(double money) {
        if (money < 0) {
            throw new IllegalArgumentException("Money cannot be negative");
        }
        this.money = money;
    }

    public void buyProduct(Product product) {
        if (product == null) {
            throw new IllegalArgumentException();
        }
        if (this.money - product.getCost() < 0) {
            throw new IllegalArgumentException(String.format("%s can't afford %s", this.name, product.getName()));
        }
        this.products.add(product);
        this.setMoney(this.money - product.getCost());
        System.out.println(String.format("%s bought %s", this.name, product.getName()));

    }


Main-----


try {
            getPeople();
            getProducts();

            String input;
            while (!"end".equalsIgnoreCase(input = reader.readLine())) {
                String[] tokens = input.split("\\s+");
                String name = tokens[0];
                String productName = tokens[1];
                if (people.containsKey(name) && products.containsKey(productName)) {
                    Person person = people.get(name);
                    Product product = products.get(productName);

                    person.buyProduct(product);
                }
            }
        } catch (IllegalArgumentException iae) {
            System.out.println(iae.getMessage());
        } catch (IOException e) {
            e.printStackTrace();
        }
        people.values()
                .forEach(System.out::println);
    }