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.

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.

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.

The Memento pattern is used to store the state of an object so that it can be restored later.

Design Patterns are usually categorized into three types: Creational, Structural, and Behavioral. Creational patterns deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. Structural patterns deal with object composition, creating relationships between objects to form larger structures. Behavioral patterns focus on communication between objects, what goes on between objects and how they operate together.

The Strategy design pattern allows an object to change its behavior at runtime, while the State design pattern changes the behavior of an object based on its internal state.

The best way to prevent cloning of a singleton object in Java is by throwing a CloneNotSupportedException in the clone method. This will make the class not cloneable and prevent other objects from attempting to create a copy of the singleton object.

The Service Locator pattern involves a centralized object that provides access to dependencies, while Dependency Injection provides objects to dependencies through constructor injection, method injection, or setter injection.

The Intercepting Filter pattern is a design pattern used in web applications to pre-process requests before they are sent to the target resource. This is done to add additional functionality to the request such as security checks, data validation, or header modification.

The Factory pattern is a creational design pattern that provides a way to create objects in a more efficient and centralized manner. The Factory pattern abstracts the process of object creation and allows the client code to be decoupled from the actual implementation of the objects being created. This allows for greater flexibility and maintainability in the code, as the specific implementation of the objects can be changed without affecting the client code.