Software design patterns
Design patterns is a general reusable solution to some commonly occurring problem in software design.
- 1 Creational patterns
- 2 Structural pattern
- 3 Behavioral pattern
- 4 Concurrency pattern
- 5 Leaders followers pattern
Creational patterns deal with object creation mechanisms, trying to create objects in a manner suitable to the situation.
The abstract factory pattern provides a way to encapsulate a group of individual factories that have a common theme.
the Factory method pattern deals with the problem of creating objects (products) without specifying the exact class of object that will be created.
The Builder pattern separate the construction of a complex object from its representation so that the same construction process can create different representations
Prototype pattern is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects
- Lazy initialization pattern is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed
- Object pool is a set of initialised objects that are kept ready to use, rather than allocated and destroyed on demand
- Singleton pattern restrict instantiation of a class to one object
Structural Design Patterns ease the design by identifying a simple way to realize relationships between entities.
The adapter pattern adapts one interface for a class into one that a client expects
The bridge pattern decouple an abstraction from its implementation so that the two can vary independently.
The composite pattern is a tree structure of objects where every object has the same interface.
- Java Design Patterns Learning Design Patterns
- w:Aggregate pattern: a version of the Composite pattern with methods for aggregation of children
- w:Decorator pattern: add additional functionality to a class at runtime where subclassing would result in an exponential rise of new classes
- w:Extensibility pattern: aka. Framework - hide complex code behind a simple interface
- w:Facade pattern: create a simplified interface of an existing interface to ease usage for common tasks
- w:Flyweight pattern: a high quantity of objects share a common properties object to save space
- w:Proxy pattern: a class functioning as an interface to another thing
- w:Pipes and filters: a chain of processes where the output of each process is the input of the next
- w:Private class data pattern: restrict accessor/mutator access
behavioral design patterns identify common communication patterns between objects and realize these patterns.
The strategy pattern defines a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
Template method pattern
The template method pattern describes the program skeleton of a program in an operation, deferring some steps to subclasses.
- w:Chain of responsibility pattern: Command objects are handled or passed on to other objects by logic-containing processing objects
- w:Command pattern: Command objects encapsulate an action and its parameters
- w:Interpreter pattern: Implement a specialized computer language to rapidly solve a specific set of problems
- w:Iterator pattern: Iterators are used to access the elements of an aggregate object sequentially without exposing its underlying representation
- w:Mediator pattern: Provides a unified interface to a set of interfaces in a subsystem
- w:Memento pattern: Provides the ability to restore an object to its previous state (rollback)
- w:Null Object pattern: designed to act as a default value of an object
- w:Observer pattern: aka Publish/Subscribe or Event Listener. Objects register to observe an event which may be raised by another object
- w:State pattern: A clean way for an object to partially change its type at runtime
- w:Specification pattern: Recombinable Business logic in a boolean fashion
- w:Visitor pattern: A way to separate an algorithm from an object
- w:Single-serving visitor pattern: Optimise the implementation of a visitor that is allocated, used only once, and then deleted
Concurrency patterns are one of the types of design patterns. Examples of this class of patterns include:
- w:Active Object
- w:Balking pattern
- w:Double checked locking pattern
- w:Guarded suspension
- Leaders/followers pattern
- Monitor Object
- w:Read write lock pattern
- w:Scheduler pattern
- w:Thread pool pattern
- w:Thread-Specific Storage
- w:Reactor pattern
Leaders followers pattern
Examples of this class of patterns include: