Java Design Patterns (Creational, Structural, Behavioral)
Java Design Patterns are standard solutions to common software design problems, categorized into three primary types: Creational, Structural, and Behavioral patterns. Creational patterns, such as Singleton, Factory, and Builder, focus on object creation mechanisms, providing flexibility and control over instantiation. Structural patterns, including Adapter, Composite, and Proxy, deal with object composition, enabling the creation of complex structures while promoting simplicity and reusability. Behavioral patterns, like Observer, Strategy, and Command, emphasize communication and responsibility among objects, defining how they interact and collaborate. Together, these patterns enhance code maintainability, scalability, and readability, aiding developers in crafting robust Java applications.
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1 - Singleton Pattern: Ensures a class has only one instance and provides a global point of access to it. This is useful for shared resources like configuration settings.
2) Factory Method Pattern: Defines an interface for creating an object, but allows subclasses to alter the type of created objects. This decouples the client code from the object creation logic.
3) Abstract Factory Pattern: Provides an interface for creating families of related or dependent objects without specifying their concrete classes. Useful for ensuring that products match across different categories.
4) Builder Pattern: Separates the construction of a complex object from its representation. This allows the same construction process to create different representations (e.g., creating a complex Meal with different components).
5) Prototype Pattern: Creates new objects by copying an existing object, known as the prototype. This is useful for situations where object creation is costly or complex.
6) Adapter Pattern: Allows incompatible interfaces to work together. It acts as a bridge between two incompatible types by wrapping one interface around another.
7) Decorator Pattern: Provides a flexible alternative to subclassing for extending functionality. This pattern allows dynamic addition of behavior to individual objects without affecting other objects from the same class.
8) Facade Pattern: Offers a simplified interface to a complex subsystem. It defines a higher level interface that makes the subsystem easier to use.
9) Composite Pattern: Composes objects into tree structures to represent part whole hierarchies. This pattern allows clients to work with individual objects and compositions uniformly.
10) Bridge Pattern: Decouples an abstraction from its implementation so that the two can vary independently. This is useful for systems that need to support multiple implementations.
11) Observer Pattern: Defines a one to many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. This is widely used in event handling systems.
12) Strategy Pattern: Defines a family of algorithms, encapsulates each one, and makes them interchangeable. This allows the algorithm to vary independently from clients that use it.
13) Command Pattern: Encapsulates a request as an object, thereby allowing for parameterization of clients with queues, requests, and operations. This pattern is useful for implementing undo mechanisms.
14) State Pattern: Allows an object to alter its behavior when its internal state changes. The object will appear to change its class, which is useful for implementing state machines.
15) Template Method Pattern: Defines the skeleton of an algorithm in a method, deferring some steps to subclasses. This pattern lets the subclasses redefine certain steps of an algorithm without changing its structure.
16) Visitor Pattern: Allows adding new operations to existing object structures without modifying the structures. This pattern separates an algorithm from the object structure on which it operates.
Design Patterns are crucial for writing clean, reusable, and maintainable code. Understanding and applying these patterns will significantly enhance the students’ programming and architectural skills in Java and software development in general.
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