Explore Questions and Answers to deepen your understanding of Object Oriented Programming.
Object Oriented Programming (OOP) is a programming paradigm that organizes code into objects, which are instances of classes. It focuses on the concept of objects, their properties (attributes), and their behaviors (methods). OOP allows for the encapsulation of data and methods within objects, promoting modularity, reusability, and flexibility in software development. It also supports concepts such as inheritance, polymorphism, and abstraction, which enhance code organization and facilitate code maintenance.
The main principles of Object-Oriented Programming (OOP) are:
1. Encapsulation: It is the process of bundling data and methods together into a single unit called an object. Encapsulation allows for data hiding and ensures that the internal workings of an object are hidden from the outside world.
2. Inheritance: It is a mechanism that allows a class to inherit properties and behaviors from another class. Inheritance promotes code reuse and allows for the creation of hierarchical relationships between classes.
3. Polymorphism: It is the ability of an object to take on many forms. Polymorphism allows objects of different classes to be treated as objects of a common superclass, enabling flexibility and extensibility in the code.
4. Abstraction: It is the process of simplifying complex systems by breaking them down into smaller, more manageable parts. Abstraction allows for the creation of abstract classes and interfaces, which define common behaviors and characteristics that can be implemented by multiple classes.
These principles form the foundation of OOP and help in creating modular, reusable, and maintainable code.
A class in Object Oriented Programming (OOP) is a blueprint or template that defines the properties (attributes) and behaviors (methods) of objects. It serves as a blueprint for creating multiple instances of objects with similar characteristics. A class encapsulates data and functions into a single unit, allowing for code reusability and modularity.
An object in Object-Oriented Programming (OOP) is an instance of a class that encapsulates data and behavior. It represents a real-world entity or concept and can have its own unique attributes (data) and actions (methods). Objects are the building blocks of OOP and are used to model and manipulate data in a structured and modular way.
Encapsulation in Object-Oriented Programming (OOP) is the concept of bundling data and methods together within a class, and controlling access to them through the use of access modifiers. It allows for the hiding of internal implementation details and provides a way to protect data from being accessed or modified directly by external entities. Encapsulation promotes data integrity and code reusability by enforcing the principle of information hiding.
Inheritance in Object Oriented Programming (OOP) is a mechanism that allows a class to inherit properties and behaviors from another class. It enables the creation of a hierarchy of classes, where a derived class (also known as a subclass or child class) inherits the attributes and methods of a base class (also known as a superclass or parent class). This means that the derived class can reuse and extend the functionality of the base class, promoting code reusability and modularity. Inheritance facilitates the concept of "is-a" relationship, where the derived class is considered to be a specialized version of the base class.
Polymorphism in Object-Oriented Programming (OOP) refers to the ability of an object to take on multiple forms or have multiple behaviors. It allows objects of different classes to be treated as objects of a common superclass, enabling them to be used interchangeably. Polymorphism is achieved through method overriding and method overloading. Method overriding allows a subclass to provide a different implementation of a method that is already defined in its superclass, while method overloading allows multiple methods with the same name but different parameters to coexist in a class. Polymorphism enhances code reusability, flexibility, and extensibility in OOP.
Abstraction in Object Oriented Programming (OOP) refers to the process of simplifying complex systems by breaking them down into smaller, more manageable components. It involves identifying the essential characteristics and behaviors of an object or a class, while hiding unnecessary details. Abstraction allows programmers to focus on the relevant aspects of an object or a class, making the code more modular, reusable, and easier to understand. It is achieved through the use of abstract classes, interfaces, and inheritance in OOP languages like Java or C++.
A constructor in Object Oriented Programming (OOP) is a special method that is used to initialize objects of a class. It is called automatically when an object is created and is used to set the initial values of the object's attributes or perform any necessary setup tasks. The constructor typically has the same name as the class and can have parameters to accept values that are used to initialize the object.
A destructor in Object Oriented Programming (OOP) is a special member function that is automatically called when an object is destroyed or goes out of scope. It is used to release any resources or memory allocated by the object during its lifetime. The destructor has the same name as the class, preceded by a tilde (~). It is primarily used to perform cleanup operations, such as closing files, releasing memory, or releasing any other system resources held by the object.
Method overloading in object-oriented programming (OOP) refers to the ability to define multiple methods with the same name but different parameters within a class. It allows a class to have multiple methods with the same name but different functionalities based on the type, number, or order of the parameters. The compiler determines which method to execute based on the arguments passed during the method call. Method overloading helps in code reusability, improves readability, and provides flexibility in designing classes.
Method overriding in object-oriented programming (OOP) refers to the ability of a subclass to provide a different implementation of a method that is already defined in its superclass. This allows the subclass to modify or extend the behavior of the inherited method according to its specific requirements. The overridden method in the subclass must have the same name, return type, and parameters as the method in the superclass. When the overridden method is called on an object of the subclass, the subclass's implementation is executed instead of the superclass's implementation. Method overriding is a key feature of polymorphism in OOP, enabling the flexibility and customization of behavior in different subclasses.
A static method in object-oriented programming (OOP) is a method that belongs to the class itself rather than an instance of the class. It can be called directly on the class without the need to create an object of that class. Static methods are commonly used for utility functions or operations that do not require access to instance-specific data. They are defined using the "static" keyword and can only access other static members of the class.
A static variable in Object Oriented Programming (OOP) is a variable that is shared by all instances of a class. It is declared using the "static" keyword and is not tied to any specific object or instance. Instead, it belongs to the class itself. This means that any changes made to a static variable will be reflected across all instances of the class. Static variables are typically used to store data that is common to all objects of a class, such as a counter or a constant value.
A final class in Object Oriented Programming (OOP) is a class that cannot be inherited or extended by any other class. It is the last level of inheritance hierarchy and cannot have any subclasses. The final keyword is used to declare a class as final. This is often done to prevent any modifications or extensions to the class, ensuring that its implementation remains unchanged.
A final method in object-oriented programming (OOP) is a method that cannot be overridden or modified by any subclass. Once a method is declared as final, it cannot be changed or extended in any way by any derived class. This is often used to ensure that certain critical methods in a class cannot be altered, providing stability and preventing unintended modifications.
An abstract class in Object Oriented Programming (OOP) is a class that cannot be instantiated and is meant to serve as a blueprint for other classes. It contains one or more abstract methods, which are methods without any implementation. These abstract methods must be implemented by any concrete subclass that extends the abstract class. Abstract classes can also have non-abstract methods with implementation, which can be inherited by the subclasses. The main purpose of an abstract class is to provide a common interface and define common behavior for its subclasses.
In object-oriented programming (OOP), an interface is a collection of abstract methods that define a contract for classes to implement. It acts as a blueprint for classes, specifying the methods that must be implemented by any class that implements the interface. An interface defines the behavior that a class should exhibit, without providing any implementation details. It allows for the concept of multiple inheritance, as a class can implement multiple interfaces. Interfaces enable code reusability, modularity, and flexibility in OOP.
In object-oriented programming (OOP), a package is a way to organize and group related classes, interfaces, and other resources together. It provides a mechanism for creating a namespace and helps in avoiding naming conflicts. Packages also enable better code organization, reusability, and modularity by allowing easy access and management of related components.
A namespace in Object Oriented Programming (OOP) is a container that holds a collection of related classes, objects, functions, and variables. It helps in organizing and managing the elements of a program by providing a unique identifier for each element within the namespace. This prevents naming conflicts and allows for better code organization and modularity. Namespaces also enable the reuse of names across different parts of a program without causing conflicts.
Method hiding in object-oriented programming refers to the concept where a subclass defines a method with the same name as a method in its superclass, thereby hiding the superclass method. This means that when the method is called on an object of the subclass, the subclass method is executed instead of the superclass method. Method hiding is achieved by using the "static" keyword in the subclass method declaration.
Method chaining in object-oriented programming (OOP) refers to the practice of calling multiple methods on an object in a single line of code. This is achieved by returning the object itself from each method call, allowing subsequent methods to be called on the same object. Method chaining enhances code readability and conciseness, as it eliminates the need for intermediate variables and reduces the number of lines of code required to perform multiple operations on an object.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It serves as a blueprint for creating multiple instances of objects with similar characteristics. A class defines the common attributes and methods that objects of that class will possess.
On the other hand, an object is an instance of a class. It is a tangible entity that represents a specific occurrence or realization of a class. Objects have their own unique set of attributes and can perform actions or methods defined within the class. Each object created from a class can have different values for its attributes while still maintaining the same structure and behavior defined by the class.
In summary, a class is a general template or blueprint that defines the structure and behavior of objects, while an object is a specific instance of a class with its own unique set of attributes and behaviors.
Inheritance and composition are two fundamental concepts in Object-Oriented Programming (OOP) that allow for code reuse and building relationships between classes.
Inheritance is a mechanism where a class (called the child or derived class) inherits properties and behaviors from another class (called the parent or base class). The child class can access and use the attributes and methods of the parent class, extending or modifying them as needed. Inheritance promotes code reuse and supports the "is-a" relationship, where a child class is a specialized version of the parent class.
Composition, on the other hand, is a design technique where a class contains an instance of another class as one of its member variables. It represents a "has-a" relationship, where an object is composed of other objects. The composed object can be used to provide specific functionality to the containing class, and it can be easily replaced or modified at runtime. Composition promotes flexibility and code organization.
In summary, the main difference between inheritance and composition in OOP is that inheritance focuses on the relationship between classes, allowing for code reuse and specialization, while composition focuses on the relationship between objects, allowing for flexibility and modular design.
Method overloading and method overriding are both concepts in object-oriented programming (OOP) that involve the use of methods, but they have distinct differences.
Method overloading refers to the ability to define multiple methods with the same name but different parameters within a class. These methods can have different data types, different numbers of parameters, or both. The compiler determines which method to execute based on the arguments passed during the method call. Method overloading allows for flexibility and code reusability, as it provides different ways to perform similar operations.
On the other hand, method overriding occurs when a subclass provides a specific implementation of a method that is already defined in its superclass. The method in the subclass must have the same name, return type, and parameters as the method in the superclass. By overriding a method, the subclass can modify or extend the behavior of the inherited method. Method overriding is a fundamental feature of inheritance in OOP, allowing for polymorphism and dynamic method dispatch.
In summary, the main difference between method overloading and method overriding is that method overloading involves multiple methods with the same name but different parameters within a class, while method overriding occurs when a subclass provides a specific implementation of a method that is already defined in its superclass.
The main difference between an abstract class and an interface in Object-Oriented Programming (OOP) is that an abstract class can have both implemented and unimplemented methods, while an interface can only have unimplemented methods.
An abstract class serves as a blueprint for other classes and can contain both regular methods with implementations and abstract methods without implementations. It can also have instance variables and constructors. However, an abstract class cannot be instantiated, meaning you cannot create objects directly from it. Instead, it is meant to be extended by other classes, which must provide implementations for the abstract methods.
On the other hand, an interface is a collection of abstract methods that define a contract for classes to follow. It only contains method signatures without any implementations. An interface can also include constant variables. Classes can implement multiple interfaces, allowing them to inherit the method signatures and define their own implementations. Unlike abstract classes, interfaces cannot have instance variables or constructors.
In summary, while both abstract classes and interfaces provide a way to define common behavior for classes, abstract classes can have both implemented and unimplemented methods, while interfaces can only have unimplemented methods.
The main difference between a static method and an instance method in Object-Oriented Programming (OOP) is how they are accessed and used.
1. Static Method:
- A static method belongs to the class itself, rather than an instance of the class.
- It can be accessed directly using the class name, without creating an object/instance of the class.
- Static methods are commonly used for utility functions or operations that do not require any specific instance data.
- They cannot access or modify instance variables or methods directly.
- Static methods are shared among all instances of the class.
2. Instance Method:
- An instance method belongs to a specific instance/object of a class.
- It can only be accessed through an object/instance of the class.
- Instance methods can access and modify instance variables and other instance methods directly.
- They are used to perform actions or operations specific to an individual object/instance.
- Each instance of a class has its own copy of instance variables and can have different values.
In summary, static methods are associated with the class itself and can be accessed without creating an instance, while instance methods are associated with specific instances/objects of the class and can access instance variables and methods.
In Object-Oriented Programming (OOP), the main difference between a static variable and an instance variable lies in their scope and memory allocation.
A static variable, also known as a class variable, is shared among all instances of a class. It is declared using the "static" keyword and is stored in a common memory location. This means that any changes made to a static variable will be reflected in all instances of the class. Static variables are accessed using the class name, rather than through an instance of the class.
On the other hand, an instance variable, also known as a non-static variable, is unique to each instance of a class. It is declared without the "static" keyword and is allocated memory separately for each object. Each instance of the class has its own copy of the instance variable, and changes made to it will only affect that specific instance.
In summary, the key differences between a static variable and an instance variable in OOP are:
- Scope: Static variables are shared among all instances of a class, while instance variables are unique to each instance.
- Memory allocation: Static variables are stored in a common memory location, whereas instance variables are allocated memory separately for each object.
- Access: Static variables are accessed using the class name, while instance variables are accessed through an instance of the class.
Early binding and late binding are two concepts in object-oriented programming that refer to the timing of linking a method or function call to its implementation.
Early binding, also known as static binding or compile-time binding, occurs when the method or function call is linked to its implementation during the compilation phase. This means that the compiler determines the specific method or function to be called based on the declared type of the object or variable. Early binding provides faster execution as the binding is resolved at compile-time.
Late binding, also known as dynamic binding or runtime binding, occurs when the method or function call is linked to its implementation during the runtime or execution phase. This means that the specific method or function to be called is determined at runtime based on the actual type of the object or variable. Late binding allows for more flexibility and extensibility as it enables polymorphism and method overriding.
In summary, the main difference between early binding and late binding in OOP is the timing of linking a method or function call to its implementation. Early binding occurs at compile-time, while late binding occurs at runtime.
In object-oriented programming (OOP), composition and aggregation are two different ways of establishing relationships between classes or objects.
Composition is a strong form of association where one class (the composite) is composed of one or more instances of another class (the component). The component objects have no independent existence and are tightly bound to the composite object. This means that when the composite object is destroyed, the component objects are also destroyed. The composite object controls the creation, lifetime, and destruction of its component objects.
Aggregation, on the other hand, is a weaker form of association where one class (the aggregate) has a reference to another class (the member). The member objects have an independent existence and can exist outside the scope of the aggregate object. In aggregation, the member objects can be shared among multiple aggregate objects. When the aggregate object is destroyed, the member objects are not automatically destroyed.
In summary, the main difference between composition and aggregation in OOP lies in the strength of the relationship and the lifetime of the associated objects. Composition represents a strong "whole-part" relationship where the component objects are tightly bound to the composite object, while aggregation represents a weaker "has-a" relationship where the member objects have an independent existence and can be shared among multiple aggregate objects.
Method hiding and method overriding are two different concepts in object-oriented programming (OOP).
Method hiding refers to the situation where a subclass defines a static method with the same name as a static method in its superclass. In this case, the subclass method hides the superclass method, and the subclass method is called when the method is invoked on an object of the subclass. This is determined at compile-time based on the reference type, not the actual object type. Method hiding is achieved by using the "new" keyword in C# or by not using any specific keyword in Java.
On the other hand, method overriding occurs when a subclass defines a method with the same name and signature as a method in its superclass. In this case, the subclass method overrides the superclass method, and the subclass method is called when the method is invoked on an object of the subclass. This is determined at runtime based on the actual object type. Method overriding is achieved by using the "override" keyword in C# or by using the "@Override" annotation in Java.
In summary, the main difference between method hiding and method overriding is that method hiding is determined at compile-time based on the reference type, while method overriding is determined at runtime based on the actual object type.
The main difference between a constructor and a method in Object-Oriented Programming (OOP) is their purpose and usage.
A constructor is a special method that is automatically called when an object is created from a class. Its primary purpose is to initialize the object's state and allocate memory for it. Constructors have the same name as the class and do not have a return type. They are typically used to set initial values for the object's attributes or perform any necessary setup operations.
On the other hand, a method is a function defined within a class that performs a specific action or behavior. Methods are used to manipulate the object's data, perform operations, or provide functionality. They can have various return types and can be called multiple times throughout the program's execution.
In summary, constructors are used to initialize objects and allocate memory, while methods are used to perform actions and provide functionality within the object.
In object-oriented programming (OOP), the main difference between a class and a struct lies in their default access modifiers and their intended usage.
1. Default Access Modifiers:
- In a class, the default access modifier for its members (variables and methods) is "private". This means that the members are only accessible within the class itself.
- In a struct, the default access modifier for its members is "public". This means that the members can be accessed from outside the struct.
2. Intended Usage:
- Classes are typically used for creating complex objects that have both data and behavior. They are used to model real-world entities or concepts and support features like inheritance, encapsulation, and polymorphism.
- Structs, on the other hand, are primarily used for lightweight data structures that contain a small number of related variables. They are often used for representing simple data types (e.g., coordinates, points) and are more suitable for performance-critical scenarios.
Additionally, there are some technical differences between classes and structs in terms of memory allocation, default constructor behavior, and passing them as function parameters. However, the main distinction lies in their default access modifiers and intended usage.
In object-oriented programming (OOP), a class is a blueprint or template for creating objects. It defines the properties (attributes) and behaviors (methods) that an object of that class will have. A class can be instantiated to create multiple objects.
On the other hand, an interface in OOP is a collection of abstract methods. It defines a contract or set of rules that a class must follow if it implements that interface. An interface does not provide any implementation details, only the method signatures. A class can implement multiple interfaces, but it cannot inherit from multiple classes.
In summary, the main difference between a class and an interface in OOP is that a class is a blueprint for creating objects with defined properties and behaviors, while an interface is a contract that a class must adhere to by implementing the specified methods.
In Object Oriented Programming (OOP), a class is a blueprint or template for creating objects, which defines the properties and behaviors that the objects will have. It encapsulates data and functions into a single unit.
On the other hand, a module is a collection of related functions, variables, and classes that can be used in a program. It is a separate file or unit that can be imported and used in other parts of the program.
The main difference between a class and a module is that a class is used to create objects and define their properties and behaviors, while a module is used to organize and group related functions, variables, and classes together for reusability and maintainability. Classes are used to create instances and represent real-world entities, while modules are used to organize and modularize code for better organization and code reuse.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of objects. It encapsulates data and methods that can be used to create multiple instances of objects with similar characteristics.
On the other hand, a package is a way to organize related classes and interfaces in a hierarchical manner. It provides a means to group classes together, making it easier to manage and maintain the codebase. Packages help in avoiding naming conflicts and provide better code organization and reusability.
In summary, the main difference between a class and a package in OOP is that a class defines the structure and behavior of individual objects, while a package is a container that holds multiple classes and provides a way to organize and manage them effectively.
In Object Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It encapsulates data and functions into a single unit. It serves as a blueprint for creating objects, which are instances of the class.
On the other hand, a namespace is a container that holds a collection of related classes, interfaces, functions, and other objects. It provides a way to organize and group related code elements together, preventing naming conflicts and improving code readability and maintainability.
In summary, the main difference between a class and a namespace in OOP is that a class defines the structure and behavior of an individual object, while a namespace provides a way to organize and group related classes and other code elements together.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of objects. It serves as a blueprint for creating multiple instances of objects with similar characteristics. A class encapsulates data and methods that operate on that data.
On the other hand, a file is a storage unit that contains source code written in a programming language. It is used to store and organize code, including class definitions, functions, and other program elements. A file can contain one or more classes, along with other code elements.
In summary, the main difference between a class and a file in OOP is that a class represents a blueprint for creating objects, while a file is a container that holds the source code, including class definitions, necessary for the execution of a program.
In Object Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It serves as a blueprint for creating instances or objects of that class. A class encapsulates data and methods that operate on that data.
On the other hand, a library in OOP refers to a collection of pre-written classes, functions, and methods that can be used by programmers to simplify their coding tasks. Libraries provide reusable code and often serve specific purposes, such as handling file operations, networking, or user interface components.
In summary, the main difference between a class and a library in OOP is that a class is a fundamental building block used to create objects, while a library is a collection of classes and functions that provide additional functionality and can be used by programmers to enhance their code.
In object-oriented programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It serves as a blueprint for creating instances or objects of that class. A class encapsulates data and methods that operate on that data.
On the other hand, a framework is a collection of classes, libraries, and tools that provide a foundation for building applications. It is a reusable and customizable set of pre-written code that provides a structure and guidelines for developing software. A framework typically includes predefined classes and functions that can be used to build specific types of applications.
In summary, the main difference between a class and a framework in OOP is that a class is a single entity that defines the structure and behavior of an object, while a framework is a collection of classes and tools that provide a foundation for building applications.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of objects. It serves as a blueprint for creating multiple instances of objects with similar characteristics. A class encapsulates data and methods that define the behavior of objects.
On the other hand, a program in OOP refers to a set of instructions or code that is written to solve a specific problem or perform a particular task. It is a collection of classes, objects, and functions that work together to achieve a desired outcome. A program utilizes classes to create objects and define their behavior, allowing for the execution of specific tasks.
In summary, the main difference between a class and a program in OOP is that a class is a blueprint or template for creating objects, while a program is a collection of classes, objects, and functions that work together to solve a problem or perform a task.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of objects. It encapsulates data and functions into a single unit. A class serves as a blueprint for creating multiple instances of objects with similar characteristics.
On the other hand, a project in OOP refers to a collection of classes, resources, and files that work together to achieve a specific goal or functionality. It is a higher-level organizational unit that encompasses multiple classes and other components required for the development of a software application.
In summary, a class is a fundamental building block in OOP that defines the structure and behavior of individual objects, while a project is a larger entity that brings together multiple classes and resources to create a complete software solution.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of objects. It serves as a blueprint for creating multiple instances of objects with similar characteristics.
On the other hand, a solution in OOP refers to a complete program or application that is developed using the principles of OOP. It typically consists of multiple classes, objects, and their interactions to solve a specific problem or fulfill a particular requirement.
In summary, the main difference between a class and a solution in OOP is that a class is a single component that defines the structure and behavior of objects, while a solution is a complete program or application that utilizes multiple classes and objects to solve a problem.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It serves as a blueprint for creating multiple instances of objects with similar characteristics.
On the other hand, a component is a modular and reusable piece of software that can be independently developed, deployed, and maintained. It is a self-contained unit that encapsulates specific functionality and can be used as a building block in the development of larger systems.
In summary, the main difference between a class and a component in OOP is that a class defines the structure and behavior of an object, while a component is a standalone and reusable unit of software that can be used to build larger systems.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of objects. It serves as a blueprint for creating multiple instances of objects with similar characteristics.
On the other hand, a control is a user interface element or component that allows users to interact with the program. Controls are typically used to display information, receive input, or trigger actions. They are part of the graphical user interface (GUI) and are used to build the user interface of an application.
In summary, the main difference between a class and a control in OOP is that a class defines the structure and behavior of objects, while a control is a specific element used to create the user interface of an application.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It encapsulates data and functions related to that object. A class serves as a blueprint for creating multiple instances or objects of the same type.
On the other hand, a form is a graphical user interface (GUI) component that allows users to interact with the program. It is a specific type of class that represents a window or a dialog box. Forms provide a visual representation of the program's functionality and allow users to input data, view output, and interact with the application.
In summary, the main difference between a class and a form in OOP is that a class defines the structure and behavior of an object, while a form is a specific type of class that represents a GUI component for user interaction.
In Object-Oriented Programming (OOP), a class is a blueprint or template that defines the properties and behaviors of an object. It serves as a blueprint for creating multiple instances of objects with similar characteristics.
On the other hand, a window is a graphical user interface (GUI) element that represents a visible area on the screen. It is typically used to display information, receive user input, and interact with the user. In the context of OOP, a window is an instance of a class that represents a specific graphical window on the screen.
In summary, the main difference between a class and a window in OOP is that a class is a general concept or template that defines the properties and behaviors of objects, while a window is a specific instance of a class that represents a graphical user interface element on the screen.