Класс-справочник

public class City {
    private final String name;
    private final double distance;  // from center
    private final int count; // peoples
 
 
    public City(String name, double distance, int count ) {
        this.name = name;
        this.distance = distance;
        this.count = count;
    }
 
    public int getCount() {
        return count;
    }
 
    public double getDistance() {
        return distance;
    }
 
    public String getName() {
        return name;
    }
 
    @Override
    public String toString() {
        return name + " distance: " + distance + " peoples: " + count;
    }
}

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
 
 
public class CityList {
    private ArrayList<City> list;
 
    private static final Comparator<City> cName = (o1, o2) -> o1.getName().compareTo(o2.getName());
    private static final Comparator<City> cDistance = new Comparator<City>() {
        @Override
        public int compare(City o1, City o2) {
            return Double.compare(o1.getDistance(), o2.getDistance());
        }
    };
 
 
    public CityList() {
        this.list = new ArrayList<>();
    }
 
    public CityList(ArrayList<City> list) {
 
        this.list = new ArrayList<>(list);
    }
 
 
    private boolean isEmpty() {
        return list == null || list.isEmpty();
    }
 
 
    public void add(City city) {
        list.add(city);
    }
 
    public City get(int index) {
        if (isEmpty() || index < 0 || index >= list.size()) {
            return null;
        }
 
        return list.get(index);
    }
 
    public City remove(int index) {
        if (isEmpty() || index < 0 || index >= list.size()) {
            return null;
        }
 
        return list.remove(index);
    }
 
    public boolean remove(City city) {
        if (isEmpty() || city == null || list.contains(city)) {
            return false;
        }
        return list.remove(city);
    }
 
    public City findByName(String name) {
        int index = Collections.binarySearch(list, new City(name, 0, 0), cName);
        if (isEmpty() || index < 0 || index > list.size()) {
            return null;
        }
        return list.get(index);
    }
 
    public ArrayList<City> findByShorterDistance(double distance) {
        if (isEmpty() || distance <= 0) {
            return null;
        }
        ArrayList<City> clone = new ArrayList<>(list);
        clone.sort(cDistance);
        int index = -1;
        for (City city : clone) {
            if (city.getDistance() > distance) {
                break;
            }
            index++;
        }
        if (index < 0) {
            return null;
        }
        return new ArrayList<>(clone.subList(0, index + 1));
    }
 
    public ArrayList<City> findByLongerDistance(double distance) {
        if (isEmpty() || distance <= 0) {
            return null;
        }
        ArrayList<City> clone = new ArrayList<>(list);
        clone.sort(cDistance);
        int index = -1;
        for (City city : clone) {
            if (city.getDistance() >= distance) {
                break;
            }
            index++;
        }
        if (index < 0) {
            return null;
        }
        return new ArrayList<>(clone.subList(index+1, list.size()));
 
    }
 
    public City findByDistance(double distance) {
        for (City city : list) {
            if (Double.compare(city.getDistance(), distance) == 0) {
                return city;
            }
        }
        return null;
    }
 
 
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        if (isEmpty()) {
            return "[]";
        }
        sb.append("CityList:\n");
        for (City city : list) {
            sb.append(String.format("[ %-12s dist: %4.0f km  peoples: %7d]\n", city.getName(),
                    city.getDistance(), city.getCount()));
        }
 
        return sb.toString();
    }
 
    public static void main(String[] args) {
        System.out.println("Create cities dictionary");
        CityList cityList = new CityList();
        cityList.add(new City("Архангельск", 1261, 351488));
        cityList.add(new City("Иваново", 300, 406933));
        cityList.add(new City("Краснодар", 1382, 881476));
        cityList.add(new City("Мурманск", 1895, 298096));
        cityList.add(new City("Новороссийск", 1500, 270774));
        cityList.add(new City("Омск", 2589, 1178391));
        cityList.add(new City("Самара", 1060, 1169179));
 
 
        System.out.println(cityList);
 
        System.out.println("Cities around 1200 km from Moscow");
        CityList shorter = new CityList(cityList.findByShorterDistance(1382));
        System.out.println(shorter);
 
        System.out.println("Cities father 2000 km from Moscow");
        CityList longer = new CityList(cityList.findByLongerDistance(1500));
        System.out.println(longer);
 
        System.out.println("Find by Name");
        System.out.println(cityList.findByName("Омск"));
        System.out.println(cityList.findByName("Питер"));
 
        System.out.println("Find by Distance");
        System.out.println(cityList.findByDistance(1895));
        System.out.println(cityList.findByDistance(100));
 
    }
}