HashMapExample.java

class Car {
    
    private String carType;

    public Car(String type) {
        this.carType = type;
    }

    public String getCarType() {
        return carType;
    }

    @Override
    public boolean equals(Object o) {

        if (o == this) return true;
        if (!(o instanceof Car)) {
            return false;
        }
        Car car = (Car) o;
        return car.carType.equals(carType);
    }

    @Override
    public int hashCode() {
        return Objects.hash(getCarType());
    }
}

public class Main {

    public static void main(String[] args) {

        Map<String, Car> ownerToCar = new HashMap<>();
        ownerToCar.put("JohnDoe", new Car("Fiat"));
        ownerToCar.put("SuzanneThomson", new Car("Ferrari"));

        System.out.print(ownerToCar.get("SuzanneThomson").getCarType()); // "Ferrari"
    }
}