Design Pattern

Creational Design Patterns:

Click to zoom
Singleton Pattern

SingletonEnsure that only one instance of a class is created and Provide a global access point to the object.

When to Use , Common Usage , Example: Lazy Singleton in Java, Example: Early Singleton in Java

Click to zoom
Factory Pattern

Factory(Simplified version of Factory Method) – Creates objects without exposing the instantiation logic to the client and Refers to the newly created object through a common interface.

When to Use , Common Usage

Click to zoom
Factory Method
Document Application Example
Factory Method Example

Factory MethodDefines an interface for creating objects, but let subclasses to decide which class to instantiate and Refers to the newly created object through a common interface.

When to Use , Common Usage

Click to zoom
Abstract Factory
Look & Feel Example
Abstract Pattern Example

Abstract Factory – Offers the interface for creating a family of related objects, without explicitly specifying their classes.

When to Use , Common Usage , Example: Gui Look & Feel in Java

Click to zoom
Builder Pattern
Text Converter Example
Builder Pattern Example

Builder – Defines an instance for creating an object but letting subclasses decide which class to instantiate and Allows a finer control over the construction process.

Example: Text Converter in Java

Click to zoom
Highslide JS

Prototype – Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
Click to zoom
Object Pool
Database Example
Object Pool Example

Object Pool – reuses and shares objects that are expensive to create..

When to Use , Common Usage , Sourcecode: Database Connection Pool in Java

Behavioral Design Patterns:

Click to zoom
Chain of Responsibility

Chain of Responsibiliy – It avoids attaching the sender of a request to its receiver, giving this way other objects the possibility of handling the request too.
– The objects become parts of a chain and the request is sent from one object to another across the chain until one of the objects will handle it.

Sourcecode:

Click to zoom
Command Pattern
Restaurant Example
Command Pattern Example

Command – Encapsulate a request in an object, Allows the parameterization of clients with different requests and Allows saving the requests in a queue.

Sourcecode: Buying/Selling stocks in Java

Click to zoom
Interpreter Pattern

Interpreter – Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language / Map a domain to a language, the language to a grammar, and the grammar to a hierarchical object-oriented design

Sourcecode: Romans Numerals Converter in Java

Click to zoom
Iterator Pattern

Iterator – Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

Sourcecode: Java Iterator

Click to zoom
Mediator Pattern

Mediator – Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.

Sourcecode:

Click to zoom
Observer Pattern
News Publisher Example
Highslide JS

Observer – Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

Sourcecode: News Publisher in Java

Click to zoom
Strategy Pattern
Robot Example
Highslide JS

Strategy – Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

Sourcecode: Robot Application in Java

Click to zoom
Template Method
Travel Example
Highslide JS

Template Method – Define the skeleton of an algorithm in an operation, deferring some steps to subclasses / Template Method lets subclasses redefine certain steps of an algorithm without letting them to change the algorithm’s structure.

Sourcecode: Travel Agency Application in Java

Click to zoom
Visitor Pattern
Customers Example
Visitor Pattern Example

Visitor – Represents an operation to be performed on the elements of an object structure / Visitor lets you define a new operation without changing the classes of the elements on which it operates.

Sourcecode: Customers Report Example

Click to zoom
Null Object Pattern

Null Object – Provide an object as a surrogate for the lack of an object of a given type. / The Null Object Pattern provides intelligent do nothing behavior, hiding the details from its collaborators.

Sourcecode:

Structural Design Patterns:

Click to zoom
Adapter Pattern

Adapter – Convert the interface of a class into another interface clients expect. / Adapter lets classes work together, that could not otherwise because of incompatible interfaces.
Click to zoom
Bridge Pattern
Click to zoom
Bridge Pattern

Bridge – Compose objects into tree structures to represent part-whole hierarchies. / Composite lets clients treat individual objects and compositions of objects uniformly.

Sourcecode: Object Persistence Api in Java

Click to zoom
Composite Pattern
Shapes Example
Composite Pattern Example

Composite – Compose objects into tree structures to represent part-whole hierarchies. / Composite lets clients treat individual objects and compositions of objects uniformly.

Sourcecode: Shapes Example in Java

Click to zoom
Decorator Pattern
GUI Example
Decorator Pattern Example

Decorator – add additional responsibilities dynamically to an object.

Sourcecode: Gui Application Example

Click to zoom
Flyweight Pattern
Wargame Example
Flyweight Pattern Example

Flyweight – use sharing to support a large number of objects that have part of their internal state in common where the other part of state can vary.

Sourcecode: Java Wargame Example

Click to zoom
Memento Pattern
Calculator Example
Memento Pattern Example

Memento – capture the internal state of an object without violating encapsulation and thus providing a mean for restoring the object into initial state when needed.

Source Code: Calculator Example in Java

Click to zoom
Proxy Pattern
Image Viewer
Proxy Pattern Example

Proxy – provide a “Placeholder” for an object to control references to it.

Sourcecode: Proxy Pattern in Java

Add a Comment

Your email address will not be published. Required fields are marked *