Principles of programming

Question 1

What is a class in OOP?

Answer 1

A blueprint or definition of an object that defines attributes and methods.

Question 2

What is an object?

Answer 2

An instance of a class with specific attribute values and behaviors.

Question 3

What is instantiation?

Answer 3

The process of creating an object from a class definition.

Question 4

What is a constructor?

Answer 4

A special method called when an object is instantiated to initialize attributes.

Question 5

What are attributes?

Answer 5

Variables that hold data about the object.

Question 6

What are methods?

Answer 6

Procedures or functions that define the behavior of an object.

Question 7

What is encapsulation?

Answer 7

The bundling of data (attributes) and methods that operate on the data within a class, protecting it from outside access.

Question 8

What are getters and setters?

Answer 8

Methods used to access (get) and modify (set) the values of private attributes.

Question 9

What does it mean to make an attribute private?

Answer 9

The attribute is hidden from outside access and can only be accessed through methods inside the class.

Question 10

What are access modifiers?

Answer 10

Keywords that control the visibility of class members, typically public, private, and protected.

Question 11

What is polymorphism?

Answer 11

The ability of methods to behave differently based on the object they are called on, often achieved through method overriding.

Question 12

What is inheritance?

Answer 12

A mechanism where a child class inherits attributes and methods from a parent class.

Question 13

What is method overriding?

Answer 13

When a subclass provides a specific implementation of a method already defined in its parent class.

Question 14

How is inheritance represented in UML?

Answer 14

With hollow-headed arrows pointing upward from the child class to the parent class.

Question 15

What does ‘protected’ mean in OOP?

Answer 15

Attributes or methods accessible within their class and subclasses, but not from outside.

Question 16

Why use encapsulation?

Answer 16

To protect data integrity by preventing direct access and modification of attributes.

Question 17

What is meant by ‘message passing’ in OOP?

Answer 17

Objects communicate by calling each other’s public methods.

Question 18

What is the difference between a superclass and a subclass?

Answer 18

Superclass is the parent class; subclass is the child class that inherits from the parent.

Question 19

What is ‘composition over inheritance’?

Answer 19

A design principle that favors building classes by combining simpler, stand-alone classes rather than deep inheritance hierarchies.

Question 20

What is the significance of using prewritten classes?

Answer 20

They promote code reuse and simplify system development.

Question 21

Why might OOP lead to more complex systems?

Answer 21

Because of extensive message passing and the creation of many interacting objects.

Question 22

What are some disadvantages of inheritance?

Answer 22

It can cause unintended behavior and tight coupling between classes.

Question 23

How do public and private methods differ?

Answer 23

Public methods are accessible outside the class; private methods are only used within the class.

Question 24

What is a UML class diagram?

Answer 24

A visual representation of a class showing its name, attributes, and methods.

Question 25

What is the advantage of classes being self-contained?

Answer 25

They can be reused in different applications without dependency on other parts of the system.

Question 26

What is the 'Separation of Concerns' principle?

Answer 26

Designing classes to focus on specific tasks, making systems easier to understand and maintain.

Question 27

What is method signature?

Answer 27

The name and parameters of a method used to identify it uniquely.

Question 28

What is meant by 'polymorphism allows an object to know the right method to use'?

Answer 28

At runtime, the correct overridden method is called based on the object's actual class.

Question 29

Why might objects use more memory in OOP?

Answer 29

Because each object stores its own data and methods, leading to larger memory use compared to procedural code.

Question 30

What are the benefits of modularity in classes?

Answer 30

Classes are easier to maintain, update, and reuse due to their isolated design.

Question 31

What is an attribute?

Answer 31

A variable that holds data describing the object, such as 'number of masts' in a boat.

Question 32

What is a getter?

Answer 32

A public method used to access the value of a private attribute.

Question 33

What is a setter?

Answer 33

A public method used to modify the value of a private attribute.

Question 34

What does overriding a method mean?

Answer 34

Changing the implementation of an inherited method to suit the subclass.

Question 35

Why might you use the SUPER keyword in a constructor?

Answer 35

To call the parent class constructor and avoid duplicating initialization code.

Question 36

What is the difference between private and protected attributes?

Answer 36

Private attributes are only accessible within the class; protected can also be accessed by subclasses.

Question 37

How do objects interact in OOP?

Answer 37

By passing messages, i.e., calling each other's public methods.

Question 38

What is a subclass?

Answer 38

A class that inherits from another class, also known as a child or derived class.

Question 39

What is a superclass?

Answer 39

A class from which other classes inherit, also known as a parent or base class.

Question 40

What is method signature repetition in overriding?

Answer 40

Repeating the method name and parameters in a subclass to override it.

Question 41

How does polymorphism benefit a system?

Answer 41

It allows different objects to respond to the same method call in ways appropriate to their class.

Question 42

Why is it important for classes to be self-contained?

Answer 42

So they can be reused and maintained independently without affecting other parts.

Question 43

What is the risk of tightly coupling classes through inheritance?

Answer 43

Changes in a base class can unintentionally affect all derived classes.

Question 44

What is composition in OOP?

Answer 44

Building complex classes by combining simpler objects rather than using inheritance.