Description

Introduction to object-oriented programming
1.1 Classes
1.1.1 Exercise 0
Translate the Python-program below to Java or C#:
result = “” for i in range(0,9):
for j in range(0,i): result += “*”
result += ” ”
print(result)
1
2
3
4
5
6
1.1.2 Exercise 1
Write a program that draws a smiley on the console (just like in INFDEV02-
1).
1.1.3 Exercise 2
Write an example of Python code that would cause a type error in Java/C#
1.1.4 Exercise 3
Make a static function that sums all numbers between two inputs read from the console and prints the result
1.1.5 Exercise 4
Given all semantic and typing rules in the slides, write them down in plain
English or Dutch
1.1.6 Exercise 5
Make an Interval class that:
• takes two integers, start and end, as its constructor parameters
• has a Sum method that returns the sum of all numbers between start and end
• has a Product method that returns the product of all numbers between start and end
1.1.7 Exercise 6
Make a class IntArrayOpperations that:
• takes an array of integers, as its constructor parameter
• has a Sum method that returns the sum of all numbers in the array
• has a Product method that returns the product of all numbers in the array
1.1.8 Exercise 7
A Counter with the following body:
• With a count integer attribute;
• With an empty (parameterless) constructor;
• With a method Reset;
• With a method Tick;
• (Advanced) With a static method/overloaded operator Plus which adds two counters into one;
• (Advanced) With a method OnTarget that takes as input a lambda function which will be fired when the counter reaches a given count.
1.2 Arrays
1.2.1 Exercise 8
Make a class UserStory that contains:
• 2 variables:
– hours
– description
• getters and setters for the two variables variables
• a ToString method
Moreover, in the main method instantiate 3 UserStory-objects. Write a class
Sprint that contains:
• 1 variable: an array of UserStories
• methods:
– TotalHours() which sums all the hours in the UserStories
– a ToString method
– AddUserStory which adds a UserStory to the array of Userstories
Moreover, in the main method instantiate 3 UserStory-objects.
1.3 Constructors and Collections
1.3.1 Exercise 9
We will revisit the UserStory- and Sprint-classes and extend them. In this exercise you will apply knowledge about constructors, collections
1. To both classes add a constructor which sets their instance variables.
2. In the Sprint class: Instead of an array, use an ArrayList or List to store UserStories.
4. Also, add getters for the previous variables and update the constructor.
5. UserStories have to store their status: Todo, In progress, To verify, Done. Add a variable that can store this.
6. Write methods in the Sprint-class that:
• returns the amount of hours of work still to be done in a sprint.
• returns the amount of hours already done in a sprint.
• returns if the current sprint is done
7. (Optional) The datatype you chose for the status (Todo, Done, etc.) is probably a String, right? Readup on Enums, a special type and use an enum to store the status.

Chapter 2
Reuse through polymorphism
2.1 Interfaces
2.1.1 Exercise 0
• Define an interface Animal with at least one method SaySomething that takes no arguments and returns void
• Define a Cat class that implements Animal. A cat prints on the console Miao… when SaySomething is called
• Define a Dog class that implements Animal. A dog prints on the console Bao… when SaySomething is called
• Define a Cow class that implements Animal. A cow prints on the console Muuu… when SaySomething is called
Test your program with the following codes:
• The following code Animal animal1 = new Cat(); animal1.SaySomething(); should print Miao…
• The following code Animal animal2 = new Dog(); animal2.SaySomething(); should print Bao…
• The following code Animal animal3 = new Cow(); animal3.SaySomething(); should print Muuu…
2.1.2 Exercise 1
• Make a Person interface with methods (or properties with only a getter):
– Name
– Surname
– Age
• Make the Customer, Student, Teacher implementations of Person, ensuring that they all get at least three additional methods and attributes over those in Person
2.1.3 Exercise 2
• Write a Vehicle interface with a method move and a method loadFuel; loadFuel accepts a Fuel instance, where Fuel is an interface of your writing; move returns a boolean which is true if there is enough fuel, and false otherwise
• Write a concrete class Car and a concrete class Gasoline that implement, respectively, Vehicle and Fuel; the Car checks that the given fuel is indeed Gasoline
• Write a concrete class Truck and a concrete class Diesel that implement, respectively, Vehicle and Fuel; the Truck checks that the given fuel is indeed Diesel
• Write a concrete class Enterprise and a concrete class Dilithium that implement, respectively, Vehicle and Fuel; the Enterprise checks that the given fuel is indeed Dilithium
• Make a program that receives three vehicles, without knowing their concrete type, and moves them (without resorting to conversions) until their fuel is up
2.1.4 Exercise 3
• Make a ListInt interface with methods Length, Iterate, Map, Filter, and properties (read-only) IsEmpty
• Define the concrete classes NodeInt and EmptyInt both implementing ListInt
• (Advanced) Make a ListInt, fill it with a series of numbers, increment them all by one (hint: use Map), and print them all on the screen (hint:
use Iterate)
2.1.5 Exercise 4
Basic:
• Write an IStateMachine interface with a method Update and attribute Done, where Update takes a float number and returns void, and Done is read-only and of type bool
• Write a concrete class Wait that implements IStateMachine; A Wait takes an initial time when instantiated and at every update it decreases such amount until it gets all consumed. When the time is totally consumed Done becomes true
• Write a concrete class Print that implements IStateMachine; A Print takes an initial message when instantiated and after the first update it prints the message and sets Done to true
• Write a concrete class Sequence that implements IStateMachine; A Sequence takes two IStateMachine objects when instantiated and it keeps updating the first state machine until done before start updating the second state machine. Done is set to true when both state machines are done
• Test your program with the following code new Sequence(new Wait(10), new Print(“Hello World”)). Make sure that it prints ”Hello World” after 10 seconds. For this homework use MonoGame so to get the elapsed time for each update call.
Advanced:
• Extend the IStateMachine interface with a new method Reset that takes no arguments and returns void.
• Make a Repeat class that implements IStateMachine; A Repeat takes a state machine when instantiated and at every update it keeps updating the given state machine until it is done. When the given state machine is done it gets reset, so its behavior can start all over again. The Done attribute of Repeat is always false
• Test your program with the following code new Repeat(new Sequence(new Wait(10), new Print(“Hello World”))) . Make sure that it prints ”Hello World” every 10 seconds, forever. For this homework use MonoGame so to get the elapsed time for each update call.

Chapter 3. Architectural and design considerations
Chapter 3
Architectural and design considerations
3.1 Exercises
• Write an Event abstract class or interface with a method perform;
• Write a Timer class with a method tick and a method reset; reset restarts the timer, while tick makes the timer move forward and returns whether or not the target time has been reached; when the timer reaches the target time, then fire the events in the list of timer responses
• Make a TrafficLight class which uses timers to implement red, green, and yellow lights;
• (Advanced) Rebuild timers, but this time with lambda’s instead of our custom Event.
• (Advanced) Make a Component interface;
• (Advanced) Make an Entity abstract class which houses a list of components;
• (Advanced) Write a Car class that inherits from Entity and which implements all the functionality that you would expect from a car, but with the Entity-Component model; you will need to build components for the engine, the wheels, etc. and all that the Car class does is make correct use of these components.
No reference solution yet:
Chapter 3. Architectural and design considerations

• Build an entity-component system where a Person is made up of multiple components such as shoes, clothes, make-up, personality, and intelligence (all implemented via appropriate interfaces); the Person then performs a few actions, such as doing sports, studying, and socializing through methods: the results of these actions depend on the components of the person so that, for example, doing sports with elegant shoes will have unpleasant results.