Object-Oriented Programming Concepts
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Questions and Answers

In stack memory, local variables are permanently stored until the program ends.

False

Heap memory allows objects to remain in memory until they are explicitly deleted by the programmer.

False

Indirect addressing allows multiple references to the same object in memory without creating duplicates.

True

Changing an object's property through one reference does not affect other references pointing to the same object.

<p>False</p> Signup and view all the answers

Objects are often perceived as wholes rather than focusing on their individual components.

<p>True</p> Signup and view all the answers

Person1 and Person2 are two separate objects in memory when they refer to the same Person object.

<p>False</p> Signup and view all the answers

In programming, different names can be used to refer to the same object.

<p>True</p> Signup and view all the answers

The setName method can only be called from the original reference of an object.

<p>False</p> Signup and view all the answers

A public interface includes the internal functioning of an object.

<p>False</p> Signup and view all the answers

Component objects in a composition relationship can exist independently of their composite object.

<p>False</p> Signup and view all the answers

A house can be considered a composite object containing rooms as component objects.

<p>True</p> Signup and view all the answers

Passengers in a car depend entirely on the car for their existence.

<p>False</p> Signup and view all the answers

Objects in a dependence relationship are fully dependent on each other.

<p>False</p> Signup and view all the answers

The principle of object composition reflects real-world relationships by creating complex objects from simpler ones.

<p>True</p> Signup and view all the answers

Access to component objects in a composition relationship is direct and does not require the composite object.

<p>False</p> Signup and view all the answers

In a library system, a book has a strict composite relationship with an author.

<p>False</p> Signup and view all the answers

Object-Oriented Programming (OOP) helps in organizing data and actions in a clear manner.

<p>True</p> Signup and view all the answers

Attributes are considered objects in Object-Oriented Programming.

<p>False</p> Signup and view all the answers

An entity can only be a physical object like a car or a tree.

<p>False</p> Signup and view all the answers

Selective attention allows individuals to perceive only the ambient elements around them.

<p>False</p> Signup and view all the answers

Common attributes like color apply to both trees and cars.

<p>True</p> Signup and view all the answers

Cognitive mechanisms play a role in understanding object-oriented programming through selective perception.

<p>True</p> Signup and view all the answers

Once the necessary data classes and objects are set up in OOP, data cannot be manipulated logically.

<p>False</p> Signup and view all the answers

An entity is inherently characterized by a singular attribute.

<p>False</p> Signup and view all the answers

Static variables, also known as class variables, are associated with the instance of the class rather than the class itself.

<p>False</p> Signup and view all the answers

A single copy of a static variable is shared among all instances of the class.

<p>True</p> Signup and view all the answers

this keyword in Java is used to reference the current object.

<p>True</p> Signup and view all the answers

Getter and setter methods allow modifying only class variables.

<p>False</p> Signup and view all the answers

A variable declared with the static keyword is limited to the specific instance of the class.

<p>False</p> Signup and view all the answers

Instance variables can be static, but class variables cannot be.

<p>False</p> Signup and view all the answers

In Object-Oriented Programming languages, the programmer creates and defines their own classes.

<p>True</p> Signup and view all the answers

Instance variables are accessible everywhere, while class variables are accessible only within the class where they are defined.

<p>False</p> Signup and view all the answers

Instance variables are declared inside methods of a class.

<p>False</p> Signup and view all the answers

A class constructor has the same name as the class it initializes.

<p>True</p> Signup and view all the answers

Getters are used to change the value of an object's attribute.

<p>False</p> Signup and view all the answers

Each object created from a class shares the same instance variables.

<p>False</p> Signup and view all the answers

In Java, the keyword 'new' is used to create an instance of a class.

<p>True</p> Signup and view all the answers

Setter methods follow the convention 'getAttributeName()'.

<p>False</p> Signup and view all the answers

The 'this' keyword in Java refers to the method being executed.

<p>False</p> Signup and view all the answers

Instance variables are associated with a specific instance of a class.

<p>True</p> Signup and view all the answers

In object-oriented programming, attributes are specific characteristics of objects, such as a teacher's subject or a student's grade.

<p>True</p> Signup and view all the answers

Methods in OOP are defined as static actions that cannot change based on object interaction.

<p>False</p> Signup and view all the answers

A Parking class in OOP doesn't need to store a reference to a Car object to check if a car is present.

<p>False</p> Signup and view all the answers

Inheritance allows a new class to inherit methods from a parent class, facilitating code reuse.

<p>True</p> Signup and view all the answers

In a Car class, the attributes can include features such as color and brand.

<p>True</p> Signup and view all the answers

A method that allows a teacher to 'teach a lesson' would be considered an attribute.

<p>False</p> Signup and view all the answers

The Parking class can interact with multiple Car objects simultaneously without storing references.

<p>False</p> Signup and view all the answers

OOP promotes the organization of classes in a hierarchical structure through the use of inheritance.

<p>True</p> Signup and view all the answers

Study Notes

Chapter 1: Basic Principles of Computer Science

  • The chapter focuses on the fundamental principles of computer science, specifically using object-oriented programming (OOP) to manage data.
  • Software relies on data, and effective use demands understanding, analysis, updates, and data storage.
  • OOP organizes data and actions clearly, making it understandable.
  • Data classes and objects streamline data management, making it logical.

Introduction

  • Software works with data; to effectively use data, one needs to understand, analyze, update, and store it.
  • Object-Oriented Programming (OOP) organizes data and actions related to it in a straightforward manner.
  • OOP simplifies software development, enabling efficient data management.
  • Necessary data classes and objects enable logical data handling.

Introduction (2)

  • People's perception of the environment focuses on specific objects.
  • Cognitive mechanisms play a role in this selective perception.
  • Selective attention filters out nonessential elements (ambient).
  • Objects are characterized by specific attributes (e.g., shape, color).

The trio <entity, attribute, value>

  • The trio <entity, attribute, value> describes the world using identifiable entities with attributes and values (e.g., car, color, make).
  • An entity is anything identifiable, be it a physical object, a concept, or an event.
  • Entities are perceived through their attributes.
  • Attributes define and make entities identifiable.
  • Many objects share common attributes (e.g., both cars and trees have color).

An example of the trio <entity, attribute, value>

  • A diagram (presumably a simplified ER diagram) shows a "Student" entity with attributes like Student_ID, Name, Age, Address, etc., and their corresponding values.
  • Entities (like "Student" ) are characterized by multiple attributes (color, age, size).

What is Object-Oriented Programming?

  • OOP is a coding paradigm organizing code around data (objects), not functions or procedures.
  • OOP simplifies software development by enabling the modeling of any needed data, logically.
  • OOP employs classes to define data models and blueprints for creating objects, allowing intuitive world modeling.

What is an Object?

  • An object combines data (state) and behavior (methods) within a self-contained unit.
  • State is the object's data, stored in variables or attributes (e.g., color, speed).
  • Methods define the object's actions or behavior (e.g., accelerate, brake).
  • Identity is what makes an object unique.

Storage of Objects in Memory

  • Each object is allocated memory space in the program.
  • Primitive data types have known sizes for simplified memory management.
  • Examples include integers (32 bits) and floating-point numbers (64 bits).
  • Unicode characters use 16 bits.
  • Object attributes (e.g., dimensions, colors, and brands) are stored using these primitive types.

Example of Object Memory Size Calculation

  • An example calculates the memory size of an object with attributes like age (32 bits), height (64 bits), gender (16 bits), and a name (160 bits (string with 10 characters)).
  • Total memory is 272 bits.

The Referent of an Object

  • Each object in a program has a unique name serving as an identifier.
  • This name corresponds uniquely to the object's memory address.
  • Addresses are unique, ensuring no two objects occupy the same space.
  • A referent is a variable storing an object's memory address; it's used for symbolic representations.
  • Memory addresses are typically 32 bits.
  • Efficient memory access is enabled by the referent function representing the physical address.

The Referent of an Object (2)

  • Stack memory is a short-term storage area for method data.
  • Heap memory is used to store Java objects; objects are allocated here, and unused objects are cleared automatically.
  • When a method finishes, data is removed from the stack.

Stack memory example

  • An example code snippet demonstrates how local variables are stored on the stack during method calls (e.g., 'add(int a, int b)' ).
  • The variables are placed on the stack when a method is called and removed from the stack when the method is completed.

Heap memory example

  • A code snippet demonstrates an example of how an object is stored and accessed via heap memory in Java.

Indirect Addressing

  • Several referents can access the same object in memory.
  • Referents have different names but point to the same object in memory.
  • This allows the use of objects in multiple parts or contexts of a program without needing to duplicate data.
  • Indirect addressing is a common OOP technique.

Multiple Referents Example

  • A code example demonstrates how variables can refer to the same object's data (e.g., if one object changes the value of an attribute, all referring variables will reflect the change).

The Object in Its Passive Version

  • Objects are often perceived as wholes, not components, though they do consist of sub-objects or parts.
  • The public interface focuses on how other objects interact with it.
  • The internal functionality focuses on internal object actions.
  • OOP separates exposed aspects from internal details for better organization.

Object Composition

  • A primary object (composite) contains other objects (components)
  • Components depend on the composite object (cannot exist independently).
  • Components are accessible only through the composite.
  • A house serves as a real-world example of composition (containing rooms, walls, doors).

Dependence Relationship

  • Objects can be connected but not fully dependent on each other.
  • A book depends on an author but can exist independently.
  • This is an association (not composition).

The object in its active version

  • Objects aren't static; they react to events and can change.
  • Interactions involve objects responding to signals or other objects.
  • State changes affect object attributes, reflecting their behavior.
  • Active objects contribute to program complexity and authenticity.

Object State

  • An object's state reflects its current condition based on attribute values.
  • Attributes can change, influencing an object's behavior, but the fundamental identity remains constant.
  • Modification of attributes updates their values in memory without altering the object's address.
  • An object's lifecycle follows creation, state changes, and eventual deletion.

Object Lifecycle

  • An object's lifecycle encompasses its existence from creation to deletion.
  • Stages include creation, usage, attribute modification, and destruction.
  • Memory is allocated, initializing attributes during creation.
  • Object state changes based on internal and external interactions.

Responsibility

  • Object state changes are driven by operations or methods for the object’s internal changes.
  • Methods like "change" modify attribute values for an object like a traffic light.

Exercise (Composition relationship)

  • The composition relationship dictates that a dependent object (e.g., a Room) cannot exist without its parent (House).
  • When the parent is destroyed, the dependent object is also destroyed.
  • This impacts memory management in OOP programs.

QCM

  • Multiple choice questions about object composition, their lifecycle, and attribute changes follow the rules of object-oriented (OOP) programming languages.

Introduction to the concept of a Class

  • A class is a blueprint or template outlining an object's structure and behavior.
  • Objects are instances created based on class blueprints.
  • Instance variables hold the object's data, while methods specify its actions.

Introduction to the concept of a Class (2)

  • An example of a class (presumably the 'Vehicle' class) demonstrates instance variables (e.g., 'passengers') and methods ('getPassengers', 'setPassengers') defining object behavior.

Class Constructor

  • A special method in a class, the constructor, initializes object attributes when created.
  • The "this" keyword refers to the current object, allowing access to instance variables and methods.

Getter

  • A getter method retrieves an object's attribute value.
  • It follows a standard naming convention (e.g., getAttributeName()).

Setter

  • A setter method sets or updates an object's attribute value.
  • It follows a standard naming convention (e.g., setAttributeName()).

Object instance

  • An object instance represents a class's specific realization.
  • The 'new' keyword creates an object from a class and allocates memory space to hold the object's attribute values.

Example of Object instance

  • An example demonstrates the creation of ‘Vehicle’ objects and how to use the instance variables via methods.

Instance variables and class variables

  • Instance variables belong to a specific object instance.
  • Class variables are associated with the class itself, shared among all instances.
  • Instance variables are declared within a class outside a method, constructor, or block.

Instance variables and class variables (2)

  • An example shows how instance variables (name, age) within the 'Person' class are defined.

Instance variables and class variables (3)

  • Static variables (class variables) are associated with the class, not object instances.
  • A class variable is shared across all objects of the class.
  • Class variables are declared using the static keyword.

Instance variables and class variables (4)

  • A code snippet demonstrates class variables (population) defined, shared among objects, and modified.

QCM (Additional)

  • Additional multiple-choice questions cover the role of constructors, the 'this' keyword, getter, and setter methods, the distinction between instance and class variables.

Object-Oriented Programming (OOP) Languages

  • OOP languages (e.g., Java and C++) allow programmers to create and modify their classes.
  • Defining attributes and methods using classes define the objects' behavior.

Languages Manipulating Objects

  • Languages like JavaScript primarily interact with predefined classes.
  • They create instances of existing classes rather than defining new ones.
  • Existing classes specify methods and attributes.

Executing the Method on a Specific Object

  • A method applied to a specific object needs to identify which object it acts upon.
  • The dot notation associates a method with an object (object.method()).
  • This method acts only on that object's attributes.

How Objects Communicate

  • Objects in OOP interact to perform tasks.
  • Interactions are often seen as messages passed between objects.
  • Methods act on an object's attributes when called by another object.

Finding Message Recipients

  • Object-oriented programming (OOP) ensures appropriate object handling via well-defined methods for objects.
  • Messages to an object only reflect that object's behavior.
  • The receiving object's type (e.g., Car) or any special attributes are verified.

Finding Message Recipients (2)

  • The recipient object (e.g., Parking) needs a reference to the object sending the message (e.g., Car) to respond effectively.
  • This maintains object integrity and consistency.

Inheritance

  • Inheritance creates new classes (subclasses) from existing classes (superclasses)
  • Subclasses inherit attributes and methods of their superclass(es).
  • This promotes code reuse and organizes classes hierarchically.

Hierarchy of Objects

  • OOP organizes classes in a hierarchy, from general to specific.
  • This hierarchy mirrors how people categorize objects in the real world.
  • Specific objects (e.g., iPhone) are subclasses of a broader category (e.g., phone).

Contextual Dependence on the Right Taxonomic Level

  • Everyday language often uses broad terms (e.g., "car").
  • Using very broad terms can be problematic in technical contexts.
  • The level of specificity in communication should reflect the context.

Contextual Dependence on the Right Taxonomic Level (2)

  • The level of detail in communication depends on the context.
  • In technical contexts (e.g., with mechanics), a more specific term (e.g., "Toyota Corolla") is necessary.

Polymorphism

  • Polymorphism allows different objects to respond to the same message (method call) differently.
  • The behavior differs according to the specific object's type.
  • Polymorphism complements inheritance in OOP.

Polymorphism example

  • An example illustrates how different types of objects (e.g., windows, icons) can react differently to the same action (e.g., a mouse click).

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Chapter 1: Basic Principles: Which Object for Computer Science? PDF

Description

This quiz explores fundamental concepts in object-oriented programming, focusing on memory management, object references, and the relationships between objects. Test your understanding of stack vs. heap memory, object properties, and composite objects in programming.

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