Java Design Patterns are proven solutions to common software design problems that occur during application development. They provide a standard way to organize code, improve reusability, and make applications easier to maintain and extend. Design patterns also help developers follow best practices while building scalable and flexible software systems.
- Improve code reusability and maintainability
- Provide standard solutions for recurring design problems
- Enhance communication among developers using common design terminology
1. Creational Design Patterns in Java
Creational design patterns focus on efficient and flexible object creation. They decouple the system from the process of instantiating objects, making the code more maintainable, adaptable and independent of how objects are constructed or represented.
Types of Creational Design Patterns in Java
- Factory Method Design Pattern: Defines an interface for creating objects but lets subclasses decide which class to instantiate.
- Abstract Factory Method Design Pattern: Provides an interface to create families of related objects without specifying their concrete classes.
- Singleton Method Design Pattern: Ensures that only one instance of a class exists and provides a global point of access.
- Prototype Method Design Pattern: Creates new objects by cloning existing instances instead of instantiating new ones.
- Builder Method Design Pattern: Separates the construction of a complex object from its representation, allowing step-by-step creation.
2. Structural Design Patterns in Java
Structural design patterns define how classes and objects are combined to form larger, flexible structures. They simplify object relationships, improve reusability and make systems easier to understand and maintain.
Types of Structural Design Patterns in Java
- Adapter Method Design Pattern: Converts one interface into another to make incompatible classes work together.
- Bridge Method Design Pattern: Decouples abstraction from implementation so they can vary independently.
- Composite Method Design Pattern: Treats individual objects and groups of objects uniformly in a tree structure.
- Decorator Method Design Pattern: Dynamically adds new responsibilities to objects without modifying their code.
- Facade Method Design Pattern: Provides a simplified interface to a complex subsystem.
- Flyweight Method Design Pattern: Minimizes memory use by sharing common object data instead of creating duplicates.
- Proxy Method Design Pattern: Provides a surrogate or placeholder to control access to another object.
3. Behavioral Design Patterns in Java
Behavioral design patterns are a group of design patterns that focus on how objects and classes interact and communicate in software development. They emphasize the collaboration between objects to effectively accomplish tasks and responsibilities, making the system more manageable and adaptable
Types of Behavioral Design Pattern in Java
- Chain Of Responsibility Method Design Pattern: Passes a request along a chain of handlers until one processes it.
- Command Method Design Pattern: Encapsulates a request as an object to parameterize clients and support undo/redo.
- Interpreter Method Design Pattern: Defines a grammar and provides an interpreter to evaluate language expressions.
- Mediator Method Design Pattern: Centralizes communication between objects to reduce direct dependencies.
- Memento Method Design Patterns: Captures and restores an object’s state without exposing its internals.
- Observer Method Design Pattern: Defines a one-to-many dependency so when one object changes, dependents are notified.
- State Method Design Pattern: Allows an object to change behavior dynamically when its internal state changes.
- Strategy Method Design Pattern: Defines a family of algorithms and makes them interchangeable at runtime.
- Template Method Design Pattern: Defines the skeleton of an algorithm, letting subclasses override specific steps.
- Visitor Method Design Pattern: Separates algorithms from the objects on which they operate by using a visitor class