HDBandit

maybeCar.map(Car::getAudioSystem)
      .filter(as -> "Pionner".equals(as.getBrand())
      .ifPresent(() -> System.out.println("ok"));

HDBandit

public class Car {

    private String engine;
    private String color;
    private long frameNumber;

    public Car(long frameNumber, String engine, String color) {
        this.engine = engine;
        this.color = color;
        this.frameNumber = frameNumber;

HDBandit

public class LightCar {

    private String engine;
    private String color;

    public LightCar(String engine, String color) {
        this.engine = engine;
        this.color = color;
    }

HDBandit

public class LightCarContainer {

    private static HashMap<String,LightCar> lightCars = new HashMap<String, LightCar>();
    
    public static LightCar getLightCar(String engine, String color) {
        String key = engine + color;
        if (!lightCars.containsKey(key)) {
            lightCars.put(key, new LightCar(engine,color));
        }
        return lightCars.get(key);

HDBandit

public class CarFlyWeight implements Car {
    
    private long frameNumber;
    private LightCar lightCar;

    public CarFlyWeight(long frameNumber, LightCar lightCar) {
        this.frameNumber = frameNumber;
        this.lightCar = lightCar;
    }

HDBandit

public class CarFactory {

    Car create(long frameNumber, String engine, String color) {
        return new CarFlyWeight(frameNumber, LightCarContainer.getLightCar(engine, color));
    }
}

HDBandit

// business logic
public static List<Car> filterCarsByBrand(List<Car> cars, String brand) {
  ArrayList<Car> filteredCars = new ArrayList<Car>();
  for (Car car : cars) {
    if (brand.equals(car.getBrand())) {
      filteredCars.add(car);
    }
  }
  return filteredCars;
}

HDBandit

// business logic
public static List<Car> filterCarsByBrandAndColor(List<Car> cars, String brand, String color) {
  // we can reuse the method to filtering by brand
  List<Car> filteredCarsByBrand = filterCarsByBrand(cars, brand);
  ArrayList<Car> filteredCars = new ArrayList<Car>();
  for (Car car : cars) {
    if (color.equals(car.getColor())) {
      filteredCars.add(car);
    }
  }

HDBandit

// new interface
public interface CarChecker {
  boolean check(Car car);
}

...

//business logic
public static List<Car> filterCars(List<Car> cars, CarChecker carChecker) {
  ArrayList<Car> filteredCars = new ArrayList<Car>();

HDBandit

List<Car> cars = filterCars(input, new CarChecker() {
    public boolean check(Car car) {
      return "Ferrari".equals(car.getBrand()) && "red".equals(car.getColor());
    }
  });