Class and Objects Flashcards
A high level, powerful programming language that uses the ___________________ ______________ approach
Object-oriented Programming(OOP)
A programming style that models _________________ as “objects”
real-world entities
Data ( ____ ): information or attributes
fields
Object have: (2)
- data
- Behavior
Behavior( _____ ) : Actions or functions
methods
Programs are written as _______________________ or functions.
step-by-step instructions
Programs are written as step-by-step instructions or _____________.
functions
Focuses on ________ performed on ____.
- operations
- data
Becomes hard to manage as programs _______ and ________.
grow larger and more complex
OOP:
Organized code into ________.
reusable objects
Object-Oriented Programming:
Makes software development: ?
More structured.
Easier to scale.
Simpler to maintain.
Why Use OOP in Java?
Code Reusability
Easier Maintenance
Better Security
Real-World Modeling
Java’s Popularity
Code Reusability:
Write code once and reuse it multiple times, saving _____ and_____.
time
effort
Easier Maintenance:
______ is organized into______, making it simpler to debug and update.
Code
objects
Better Security:
_______ keeps data safe from _______ or _________.
Encapsulation
unintended access
modification
Real-World Modeling:
______mirrors how________, making it ________ and practical.
OOP
objects interact in real life
intuitive
A _________ is like a blueprint or template for creating objects.
class
A class is like a ______________ or template for creating objects.
blueprint
A class is like a blueprint or __________ for creating objects.
template
A class is like a blueprint or template for ____________.
creating objects
A class is like a blueprint or template for creating objects.
It defines:
_____________: Information about the object.
___________: Actions the object can perform.
Data (fields/attributes)
Behavior (methods)
Analogy:
Think of a class as a ________ for baking a cake.
The ____________ (data) and ______ (methods).
The _________ (objects) are created using the recipe, each with unique variations (e.g., flavors, decorations).
recipe
recipe lists ingredients
steps
actual cakes
Variables in a Class:
Instance Variables:
Class Variables:
Instance Variables:
Declared inside a class but outside any method.
_______ and unique to each object.
Non-static
Class Variables:
Declared with the______________.
Shared across all objects of the class.
static keyword
What is an Object?
An object is a _____________ created from a class.
If a class is a blueprint, an object is the __________made from that blueprint.
real-world entity
actual product
____________: The process of creating an object from a class.
Instantiation
__________ are the characteristics or properties of an object.
Attributes
Attributes are the ____________________ of an object.
characteristics or properties
___________ are specific to an object and can only be accessed within that object.
Instance variables
What are Attributes?
Attributes are the characteristics or properties of an object.
They store ________ that defines what an ______ is.
Declared inside a class but outside methods.
Have data types like int, String, double, etc.
Also called ______________.
They belong to a_________.
Each object has its own copy of instance variables.
data
object
fields or instance variables
class
Java reserves ______ for the object based on the class blueprint.
memory
___________ → The name of the class.
ClassName
______________ → The name of the object (instance).
objectName
________ → This keyword allocates memory for the object.
new
__________ → Calls the class constructor to initialize the object.
ClassName()
What is a Constructor?
A ______________ used to initialize objects when they are created.
It has the same name as the class and runs automatically during object instantiation.
special method
What is a Constructor?
A special method used to initialize objects when they are created.
It has the same name as the class and runs automatically during ___________.
object instantiation
a constructor _____________ for every object you create.
sets up initial values
__________________
Assigns default values to object attributes.
Use when all objects should have the same default values.
Default Constructor (No Parameters)
___________________
Allows assigning custom values when creating an object
Requires input values.
Assigns custom values.
Use when you want different values for each object.
Constructor with Parameters
Constructor with Parameters
Allows assigning custom values when creating an object
Requires __________.
Assigns _____________.
Use when you want _______________________.
input values
custom values
different values for each object
What is “this”?
A _______________ in Java that refers to the current instance of a class.
Helps differentiate between instance variables and parameters when they have the same name.
special keyword
What is “this”?
A special keyword in Java that refers to the____________ of a__________.
Helps differentiate between__________________ when they have the same name.
current instance
class
instance variables and parameters
Why Use “this”?
Avoids _________ between instance variables and method/constructor parameters.
Allows one__________ to call another constructor in the same class (constructor chaining).
Can be used to _____________.
confusion
constructor
return the current object
When Do We Need “this”?
Most common use is when a ___________has a parameter with the same name as an instance variable.
constructor or method
Problems in the Initial Constructor
_________________:
Default values (“Unknown Product” and 0.0f) are assigned multiple times.
___________________:
Some constructors don’t initialize both attributes, leading to potential issues.
__________________:
Values are assigned manually instead of reusing logic from other constructors.
Code Duplication
Inconsistent Initialization
Lack of Constructor Chaining
Benefits of Using this:
___________: Clearly __________ between instance variables and parameters with the same name.
Avoids Confusion
distinguishes
Benefits of Using this:
Avoids Confusion: Clearly distinguishes between instance variables and parameters with the same name.
_____________: Allows one __________ to call another, reducing code duplication and __________ ______.
Constructor Chaining
constructor
improving maintainability
What are Object Methods?
Also called __________, these are__________ that belong to a specific object.
They define the _________ of an object, allowing it to perform actions, update values, or retrieve information.
instance methods
functions
behavior
They define the behavior of an object, allowing it to perform ______,_____________, or______________.
actions
update values
retrieve information
What is Encapsulation?
One of the four main principles of _________________ (OOP).
Hides the ____________ of how an object works and allows access ____________________.
Analogy: Like a medicine capsule-you can take the medicine, but you can’t see the ingredients inside.
Object-Oriented Programming
internal details
only to necessary information
Why is Encapsulation Important?
____________: Prevents direct modification of sensitive variables.
____________: Restricts access to certain parts of an object.
_______________: Allows controlled modification of values through methods.
_____________: Prevents unintended changes in the program.
Protects Data
Improves Security
Increases Flexibility
Easier Maintenance
__________: Variables or methods can only be accessed within the same class.
Private Access
Private Access: _____________ can only be accessed within the same class.
Variables or methods
Why Use Private Access?
Prevents direct ____________ of important variables.
Protects _______from unauthorized access.
Improves ___________ by restricting how data is changed.
Encourages __________ through methods.
modification
data
security
controlled access
__________: Retrieves the value of a private variable.
Accessor (Getter)
Accessor (Getter): Retrieves the ________ of a ____________.
value
private variable
_________: Modifies the value of a private variable with validation.
Mutator (Setter)
Mutator (Setter): ______ the value of a private variable with _______.
Modifies
validation
Why Are Getters and Setters Important?
___________: Variables cannot be accessed directly.
_____________: Setters validate before updating variables.
______________: Only allowed methods can modify data.
Protects Private Data
Ensures Valid Values
Provides Controlled Access
What is Method Overloading (Method Overloading)?
Allows a class to have _________ with the same name but different parameter lists.
The ___________ is called based on the ________ passed during execution.
multiple methods
correct method
arguments
Why Use Method Overloading?
___________: Reuses method names for similar actions.
_____________: Keeps related actions under the same method name.
___________: Allows calling a method with different input types or counts.
Reduces Code Duplication
Improves Readability
Provides Flexibility
Reduces Code Duplication: ____________ for similar actions.
Reuses method names
Improves Readability: Keeps related _______ under the ___________.
actions
same method name
Provides Flexibility: Allows__________ with __________input types or counts.
calling a method
different
_______________ form the foundation of _______________ in Java, enabling developers to model real-world entities in a structured and reusable way.
Classes and objects
Object-Oriented Programming (OOP)
Classes and objects form the foundation of Object-Oriented Programming (OOP) in Java, enabling developers to model _________ in a structured and ___________.
real-world entities
reusable way
A ______ acts as a ____________, defining the attributes (data) and methods (behavior) that describe what an object is and what it can do.
class
blueprint or template
A class acts as a blueprint or template, defining the _____________ and ___________ that describe what an object is and what it can do.
attributes (data)
methods (behavior)
This promotes code __________ and__________. On the other hand, an object is an instance of a class, representing a real-world entity with its own state (data) and behavior (methods).
reusability
organization
______ allow developers to create _____ and ______________ by encapsulating data and functionality into self-contained units.
Objects
modular
scalable applications
Objects allow developers to create modular and scalable applications by ___________ and ___________ into self-contained units.
encapsulating data
functionality
__________ is a key principle in OOP, ensuring that the internal details of an object are hidden and protected.
Encapsulation
Encapsulation is a key principle in OOP, ensuring that the __________ of an object are hidden and protected.
internal details
Encapsulation is a key principle in OOP, ensuring that the internal details of an object are ________ and __________.
hidden
protected
By using private access and getter/setter methods, encapsulation safeguards data and provides controlled access, enhancing ________________.
security and flexibility
_________ play a vital role in initializing objects, setting initial values for attributes, and supporting overloading to handle different initialization scenarios.
Constructors
________ define the behavior of objects and can be overloaded to perform similar actions with different inputs, improving code readability and reducing duplication.
Methods
Methods define the__________ and can be overloaded to perform similar actions with different inputs, improving code readability and reducing duplication.
behavior of objects
Methods define the behavior of objects and can be __________ to perform similar actions with different inputs, improving code readability and reducing duplication.
overloaded
Methods define the behavior of objects and can be overloaded to perform similar actions with different inputs,____________ and ____________.
improving code readability
reducing duplication
The _________ is another essential feature, referring to the current instance of a class. It helps differentiate between instance variables and parameters, enabling constructor chaining for efficient code reuse. Additionally, understanding the distinction between static and non-static members is crucial.
this keyword
The this keyword is another essential feature, referring to the __________. It helps differentiate between instance variables and parameters, enabling constructor chaining for efficient code reuse. Additionally, understanding the distinction between static and non-static members is crucial.
current instance of a class
__________belong to the class and are shared across all objects, while _____________ belong to individual objects.
Static members
non-static members
____________ are essential for breaking down complex problems into smaller, manageable parts, promoting modularity, reusability, and maintainability.
Classes and objects
