Filter and sort with a stream

 A method filters a list of Item objects based on a maximum price and then sorts the filtered items by price. Here's a summary of what the method does:

  1. Filter: It filters the items where the price is less than maxPrice.
  2. Sort: It sorts the filtered items by their price in ascending order.
  3. Collect: It collects the sorted items into a list.

Here is the code with comments and a main method added for testing:

import java.util.List;

import java.util.stream.Collectors;


class Answer {


    // Change these boolean values to control whether you see

    // the expected answer and/or hints.

    static boolean showExpectedResult = true;

    static boolean showHints = false;


    // Filter and sort the items array.

    static List<Item> getFilteredData(List<Item> items, float maxPrice) {

        return items.stream()

                    .filter(item -> item.getPrice() < maxPrice)  // Filter items by price

                    .sorted((a, b) -> Float.compare(a.getPrice(), b.getPrice()))  // Sort items by price

                    .collect(Collectors.toList());  // Collect results into a list

    }


    // A model class holding each item's values

    public static class Item {

        private int id;

        private String name;

        private float price;

        private int quantity;


        public Item(int id, String name, float price, int quantity) {

            this.id = id;

            this.name = name;

            this.price = price;

            this.quantity = quantity;

        }


        public int getId() {

            return id;

        }


        public void setId(int id) {

            this.id = id;

        }


        public String getName() {

            return name;

        }


        public void setName(String name) {

            this.name = name;

        }


        public float getPrice() {

            return price;

        }


        public void setPrice(float price) {

            this.price = price;

        }


        public int getQuantity() {

            return quantity;

        }


        public void setQuantity(int quantity) {

            this.quantity = quantity;

        }


        @Override

        public String toString() {

            return "[" + this.id + ", " + this.name + ", " + this.price + ", " + this.quantity + "]";

        }

    }


    // Main method to test the getFilteredData method

    public static void main(String[] args) {

        List<Item> items = List.of(

            new Item(1, "Item1", 10.0f, 2),

            new Item(2, "Item2", 5.0f, 4),

            new Item(3, "Item3", 20.0f, 1),

            new Item(4, "Item4", 15.0f, 3)

        );


        float maxPrice = 15.0f;

        List<Item> filteredItems = getFilteredData(items, maxPrice);


        System.out.println("Filtered and Sorted Items:");

        filteredItems.forEach(System.out::println);

    }

}

Explanation

  1. Filtering:.filter(item -> item.getPrice() < maxPrice) Filters the items to include only those with a price less than maxPrice.

  2. Sorting: .sorted((a, b) -> Float.compare(a.getPrice(), b.getPrice())) Sorts the items by their price in ascending order using Float.compare for correct floating-point comparison.

  3. Collecting: .collect(Collectors.toList()). Collects the filtered and sorted items into a list.

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