Design Pattern: Mediator

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Questions and Answers

Which design pattern is not directly related to the structure of the code provided?

Flyweight

Decorator (correct)

Bridge

Composite

What is the primary role of the Mediator interface in the given code?

To manage the lifetime of components

To provide a way to extend component functionality

To facilitate communication between components (correct)

To act as a proxy for the components

Which design pattern is most closely related to the concept of a central mediator object?

Bridge

Mediator (correct)

Proxy

Composite

Suppose we want to add additional functionality to the Button component without modifying its underlying code. Which design pattern would be most suitable for this task?

Decorator Signup and view all the answers

What is the primary difference between the Bridge and Proxy patterns?

Bridge is used for virtual access, while Proxy is used for remote access Signup and view all the answers

Which design pattern is commonly used to reduce the overhead of creating multiple instances of a heavy object?

Flyweight Signup and view all the answers

Which of the following design patterns is most closely related to the Mediator pattern in terms of its ability to reduce coupling between components?

Bridge Signup and view all the answers

What is the main benefit of using the Mediator pattern in the context of a user interface with many interconnected elements?

It enables the creation of a more modular and reusable code structure. Signup and view all the answers

How does the Mediator pattern address the issue of tight coupling between components?

By using a central mediator object to redirect calls between components. Signup and view all the answers

What is the primary role of the mediator object in the Mediator pattern?

To redirect calls between components and manage their interactions. Signup and view all the answers

Which of the following is a common scenario where the Mediator pattern is particularly useful?

When creating a user interface with many interconnected elements. Signup and view all the answers

What is the main difference between the Mediator pattern and the Composite pattern?

The Mediator pattern is used for managing interactions between components, while the Composite pattern is used for managing a hierarchical structure of components. Signup and view all the answers

How does the Mediator pattern relate to the concept of dependency injection?

The Mediator pattern is an alternative to dependency injection, as it reduces coupling between components. Signup and view all the answers

What is the main advantage of using the Mediator pattern in a large-scale application?

It makes it easier to add new components to the system without affecting existing components. Signup and view all the answers

What is the primary goal of the Mediator pattern?

To encapsulate a complex web of relations between various objects inside a single mediator object Signup and view all the answers

What is the role of the air traffic controller in the real-world analogy of the Mediator pattern?

To enforce constraints in the terminal area Signup and view all the answers

How does the Mediator pattern help in the given example of the UI dialog classes?

By eliminating mutual dependencies between various UI classes Signup and view all the answers

What is the purpose of the `notify` method in the Mediator interface?

To notify the mediator about various events Signup and view all the answers

What is the benefit of using the Mediator pattern in the given example?

It reduces the number of dependencies between objects Signup and view all the answers

What is the role of the `AuthenticationDialog` class in the given example?

It acts as the mediator to facilitate the collaboration between the UI components Signup and view all the answers

How does the Mediator pattern differ from the Bridge pattern?

The Mediator pattern reduces dependencies between objects, while the Bridge pattern creates a bridge between unrelated classes Signup and view all the answers

What is the primary difference between the Mediator pattern and the Flyweight pattern?

The Mediator pattern reduces dependencies between objects, while the Flyweight pattern shares some common state between multiple objects Signup and view all the answers

How does the Mediator pattern relate to the Decorator pattern?

The Mediator pattern reduces dependencies between objects, while the Decorator pattern adds new behaviors to individual objects dynamically Signup and view all the answers

What is the primary difference between the Mediator pattern and the Proxy pattern?

The Mediator pattern reduces dependencies between objects, while the Proxy pattern creates a proxy for another object Signup and view all the answers

Study Notes

Mediator Pattern

A behavioral design pattern that helps to reduce chaotic relationships between multiple objects.
Also known as Intermediary or Controller.

Problem

In a complex system, multiple elements may interact with each other, leading to a complex web of relationships.
Changes to one element can affect others, making it hard to reuse elements in other parts of the application.

Solution

The Mediator pattern suggests that components should not communicate directly with each other.
Instead, they should collaborate indirectly through a special mediator object.
The mediator redirects calls to appropriate components, reducing dependencies between components.

Example

A dialog for creating and editing customer profiles, consisting of multiple form controls (text fields, checkboxes, buttons).
The dialog class acts as the mediator, redirecting calls to appropriate components.

Benefits

Reduces dependencies between components, making them easier to modify, extend, or reuse.
Encapsulates complex relationships between objects inside a single mediator object.

Real-World Analogy

Aircraft pilots don't talk to each other directly; instead, they communicate through the air traffic controller.
The air traffic controller enforces constraints in the terminal area, reducing the complexity of interactions between pilots.

Pseudocode

Mediator interface declares a method for components to notify the mediator about events.
Concrete mediator class implements the mediator interface and redirects calls to appropriate components.
Components communicate with the mediator using the mediator interface.

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Description

Learn about the Mediator design pattern, its role in simplifying complex UI interactions, and how it improves system scalability.