Code snippet 1 for Loskov Substitution Principle

OcpOnly.java

// Enforce cars to have method to return mileage
interface Refuelables {
    float getMileage();
}

// Car has mileage
abstract class Car implements Refuelables {
    float fuel;
    abstract float calculateRange();
}

// Petrol car is a car
class PetrolCar extends Car {
    public PetrolCar(float fuel) { this.fuel = fuel; }
    @Override
    public float getMileage() { /* some complex logic*/ return 10f; }

    @Override
    public float calculateRange() { return this.getMileage() * this.fuel; }
}

// Diesel car is a car
class DieselCar extends Car {
    public DieselCar(float fuel) { this.fuel = fuel; }
    @Override
    public float getMileage() { /* some complex logic*/ return 15; }

    @Override
    public float calculateRange() { return this.getMileage() * this.fuel; }
}

// TripPlanner class uses Car
class TripPlanner {
    public float getRange(Car car){ return car.calculateRange(); }
}

// Press Shift twice to open the Search Everywhere dialog and type `show whitespaces`,
// then press Enter. You can now see whitespace characters in your code.
public class OcpOnly {
    public static void main(String[] args) {
        Car petrolCar = new PetrolCar(10);
        Car dieselCar = new DieselCar(10);

        TripPlanner trip = new TripPlanner();
        System.out.println("This petrol car can go: " + trip.getRange(petrolCar));
        System.out.println("This diesel car can go: " + trip.getRange(dieselCar));
    }
}

Program output:

This petrol car can go: 100.0
This diesel car can go: 150.0