Careeroza

Real World Example

Sorting Hotel Search Results

Travel sites like MakeMyTrip let users sort hotels by "Popularity", "Price: Low to High" or "Rating". Each option is just a different Comparator chosen at runtime.

Example

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Map;

public class Main {
    record Hotel(String name, int price, double rating, int reviews) { }

    static final Map<String, Comparator<Hotel>> SORTS = Map.of(
            "price", Comparator.comparingInt(Hotel::price).thenComparing(Hotel::name),
            "rating", Comparator.comparingDouble(Hotel::rating).reversed().thenComparingInt(Hotel::price),
            "popular", Comparator.comparingInt(Hotel::reviews).reversed());

    public static void main(String[] args) {
        List<Hotel> hotels = List.of(
                new Hotel("Sea View", 4200, 4.4, 1200),
                new Hotel("City Inn", 2100, 3.9, 3400),
                new Hotel("Palm Stay", 4200, 4.7, 800),
                new Hotel("Budget Rooms", 1500, 4.4, 560));

        for (String option : List.of("price", "rating", "popular")) {
            List<Hotel> sorted = new ArrayList<>(hotels);
            sorted.sort(SORTS.get(option));
            System.out.println("Sort by " + option + ":");
            sorted.forEach(h -> System.out.printf("  %-12s Rs %d  %.1f*  %d reviews%n", h.name(), h.price(), h.rating(), h.reviews()));
        }
    }
}

Output

Sort by price:
  Budget Rooms Rs 1500  4.4*  560 reviews
  City Inn     Rs 2100  3.9*  3400 reviews
  Palm Stay    Rs 4200  4.7*  800 reviews
  Sea View     Rs 4200  4.4*  1200 reviews
Sort by rating:
  Palm Stay    Rs 4200  4.7*  800 reviews
  Budget Rooms Rs 1500  4.4*  560 reviews
  Sea View     Rs 4200  4.4*  1200 reviews
  City Inn     Rs 2100  3.9*  3400 reviews
Sort by popular:
  City Inn     Rs 2100  3.9*  3400 reviews
  Sea View     Rs 4200  4.4*  1200 reviews
  Palm Stay    Rs 4200  4.7*  800 reviews
  Budget Rooms Rs 1500  4.4*  560 reviews

Practice

Exercise: Sort a list of Order(String id, LocalDate date, int amount) records: newest date first, and for the same date, highest amount first.

Show answer
orders.sort(Comparator.comparing(Order::date).reversed()
        .thenComparing(Comparator.comparingInt(Order::amount).reversed()));