Computer Science 面试题与答案
问题 46. Explain the concept of the 'Command' design pattern.
The Command design pattern encapsulates a request as an object, allowing for parameterization of clients with different requests, queuing of requests, and logging of the requests.
Example:
Implementing undo functionality in a text editor using command objects.
问题 47. What is the purpose of the 'DNS' (Domain Name System) in networking?
DNS translates human-readable domain names into IP addresses, facilitating the identification of resources on a network.
Example:
Accessing a website using its domain name (e.g., www.example.com) rather than its IP address.
问题 48. Explain the concept of the 'Singleton' design pattern.
The Singleton design pattern ensures that a class has only one instance and provides a global point of access to that instance.
Example:
Creating a single instance for a database connection manager in a web application.
问题 49. What is the purpose of the 'Observer' design pattern?
The Observer design pattern defines a one-to-many dependency between objects, so that when one object changes state, all its dependents are notified and updated automatically.
Example:
Implementing event handling in graphical user interfaces.
问题 50. Explain the concept of the 'Model-View-ViewModel' (MVVM) architectural pattern.
MVVM is an architectural pattern that separates the application into three components: Model (data and business logic), View (user interface), and ViewModel (mediator between the Model and View).
Example:
Building a cross-platform mobile app using frameworks like Xamarin.
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