Some Design Pattern

Factory Pattern:

Abstract Factory Pattern:called as factory of factories

Singleton Pattern: 

public class SingleObject {

   //create an object of SingleObject

   private static SingleObject instance = new SingleObject();

   //make the constructor private so that this class cannot be

   //instantiated

   private SingleObject(){}

   //Get the only object available

   public static SingleObject getInstance(){

      return instance;

   }

   public void showMessage(){

      System.out.println("Hello World!");

   }

}

Builder Pattern:

Builds a complex object using simple objects and using a step by step approach.

Facade Patterns:

pattern hides the complexities of the system and provides an interface to the client using which the client can access the system.

Prototype Pattern:
This pattern involves implementing a prototype interface which tells to create a clone of the current object. This pattern is used when creation of object directly is costly. For example, an object is to be created after a costly database operation. We can cache the object, returns its clone on next request and update the database as and when needed thus reducing database calls.

Proxy Pattern:
session.load() is the best example for prototype pattern: It will just create a proxy object when its really required then it loads from data base.