What is the purpose of the Null Object pattern?

  • To encapsulate complex operations and make them simple to use
  • To handle requests or operations from clients
  • To provide a substitute for a null reference
  • To separate the representation of an object from its behavior
The Null Object pattern provides an object as a substitute for a null reference, avoiding the need for checking for null values.

What is Interpreter pattern?

  • A design pattern that converts a request into a standalone object, allowing the client to parametrize objects with different requests, queue a request, or log requests
  • A design pattern that creates objects by cloning existing objects, rather than creating new instances from scratch
  • A design pattern that implements a specialized language, allowing the client to express complex operations in a simplified manner
  • A design pattern that uses shared objects to support large numbers of similar objects efficiently
Interpreter pattern is a design pattern that implements a specialized language, allowing the client to express complex operations in a simplified manner. The pattern involves creating an interpreter class that evaluates expressions in the language, and performs the operations specified by the expressions. This pattern can be useful in situations where you want to allow the client to specify complex operations in a concise and easily understandable manner.

What are J2EE Patterns?

  • A set of design patterns for software development using the C++ programming language
  • A set of design patterns for software development using the Java programming language
  • A set of design patterns for software development using the Python programming language
  • A set of design patterns for software development using the Ruby programming language
J2EE Patterns are a set of design patterns for software development using the Java programming language. These patterns provide solutions to common problems that arise in J2EE-based software development, such as implementing security, managing transactions, and integrating with other systems.

What is Service Locator pattern?

  • A behavioral pattern that describes how to distribute the communication between objects.
  • A creational pattern that provides a way to create objects without specifying the exact class of object that will be created.
  • A structural pattern that provides a centralized object registry and access to services by using a registry.
  • An architectural pattern that separates an application into objects, implementing a user interface and interface communication.
The Service Locator pattern is a J2EE design pattern that abstracts the way to look up and access objects. The objects are managed in a registry, which can be queried for services by client objects.

Is Repository Pattern as same as Active Record Pattern?

  • No, the Repository Pattern is used for complex data access, while the Active Record Pattern is used for simple data access.
  • No, the Repository Pattern is used for data access in multiple data sources, while the Active Record Pattern is used for data access in a single data source.
  • No, the Repository Pattern provides an abstraction over the data access layer, while the Active Record Pattern combines the data access and business logic in a single object.
  • Yes, the Repository Pattern and the Active Record Pattern are equivalent.
The Repository Pattern and the Active Record Pattern are different, as the Repository Pattern provides an abstraction over the data access layer, while the Active Record Pattern combines the data access and business logic in a single object.

What is Adapter pattern?

  • A design pattern that allows objects with incompatible interfaces to work together by converting the interface of one object into an interface expected by the client
  • A design pattern that creates objects by cloning existing objects, rather than creating new instances from scratch
  • A design pattern that creates objects in a step-by-step manner, allowing for more control over the object creation process
  • A design pattern that promotes the loose coupling between objects, making the system easier to maintain and extend
Adapter pattern is a design pattern that allows objects with incompatible interfaces to work together by converting the interface of one object into an interface expected by the client. This pattern involves creating a wrapper class that implements the target interface and delegates calls to the adaptee object. The adapter acts as a bridge between the adaptee and client, allowing them to work together even if their interfaces are not compatible.

What is Business Delegate pattern?

  • A design pattern that promotes loose coupling by keeping the presentation layer separate from the business layer
  • A design pattern that provides a simplified interface to a set of services
  • A design pattern that reduces the coupling between presentation-tier clients and business services
  • A design pattern that separates the business logic and presentation logic in an application
Business Delegate pattern provides a simplified interface to a set of services to reduce the coupling between presentation-tier clients and business services.

When would you use the Builder Pattern? Why not just use a Factory Pattern?

  • Use Builder Pattern when the construction process is complex with many options and Factory Pattern when the process is simple.
  • Builder Pattern is used when you want to build objects step by step, while Factory Pattern is used when you need to create objects with a single method call.
  • Use Builder Pattern when the number of object's attributes is large, while Factory Pattern is used when you need to hide the creation process.
  • Builder Pattern is used when objects cannot be created in a single step, while Factory Pattern is used when the creation process is simple.
The Builder Pattern is used when the construction of an object is complex, and it allows you to build objects step by step, with each step having a different number of options. This is useful when you want to provide a clean API for creating objects, without exposing the details of the creation process. The Factory Pattern, on the other hand, is used when you need to create objects with a single method call. This is useful when the creation process is simple, and you don't need to provide a clean API for creating objects.

What is Decorator pattern?

  • A design pattern that allows objects to be decorated with additional responsibilities, dynamically, at runtime
  • A design pattern that creates objects by cloning existing objects, rather than creating new instances from scratch
  • A design pattern that filters a set of objects based on certain criteria and returns a subset of those objects
  • A design pattern that separates an object's implementation from its interface, allowing the two to vary independently
Decorator pattern is a design pattern that allows objects to be decorated with additional responsibilities, dynamically, at runtime. The pattern involves creating a decorator class that wraps the original object, adding the new responsibilities to the original object's behavior. This pattern can be useful in situations where you want to add or remove responsibilities from objects dynamically, without affecting the behavior of the original objects.

Explain usage of Service Locator Pattern

  • The Service Locator pattern is used to access a centralized registry of service objects, so that client objects can access the services directly.
  • The Service Locator pattern is used to access a centralized registry of service objects, so that client objects do not have to depend on the concrete implementations of the services.
  • The Service Locator pattern is used to create a centralized registry of service objects, so that client objects can access the services indirectly.
  • The Service Locator pattern is used to maintain a centralized registry of service objects, so that client objects can access the services through a locator object.
The Service Locator pattern is used to maintain a centralized registry of service objects, and provides a single point of access for clients to access the services through a locator object.