If one usecase must use another usecase, then use include
relationship. If one use case may use another usecase, then
use extends relationship. uses relationship is defined in
UML 1.1.

Includes:

if(TRUE)

   include the use case

Extends:

if(condition)

   extend the use case

It's a matter of unconditional VS. conditional insertion

(Source : Uml 2002--The Unified Modeling Language
 By Jean-Marc Jézéquel, Heinrich Hussmann, Stephen Cook)

Uses:

Defined in UML 1.1

Sequence Diagrams : Diagrams used in OOAD, to describe the
event flow, w.r.t. the objects and their timelines.

Collaboration Diagrams : Diagrams used in OOAD, to describe
the interaction between the different entities(objects) in
the system.

Composition : Defines a strong-coupled relationship between
two entities, where the one entity is part of another, and
both need each other for their existence. e.g. Human body
and the Heart.

Aggregation : Defines a weak-coupled relationship between
two entities, where one entity could be part of another, but
either can exist without the other, independantly. e.g.
School and teacher.

It is used to division for sub subclassess.Abstractclassess 
are not allowed in inheritance because it has no body.

Inheritance is a type of relationship among classes, wherein
one class shares the structure or behaviour defined in one
(single inheritance) or more (multiple inheritance) other
classes. Inheritance defines a "kind of" hierarchy among
classes in which a sub class inherits from one or more
super-classes; a sub-class typically augments or redefines
the existing structure and behaviour of its super-classes.

Creating new class with existing one.

Through a Class Diagram.Class Diagram is created with a
rectengle.The top level is the name of the Class,below that
the data /variables are defined and below that the
operations related to the Class are defined

class is a rectangle shape ,class is divided in to three 
part 1.name of the class 2.attribute 3. operation

A design Pattern is a template that a software developer 
can use to solve a real world application project.  Think 
of it as an empty flow chart diagram with symbols that 
represent actions that an application will perform based on 
certain criteria. The developer can choose which pattern 
best suits their needs. There are a variety of design 
patterns and design methodologies that have been carefully 
developed for a wide range of software development 
projects.  

Chris Osgood 
Programmer Analyst 
Hallowell, Maine

Design patterns are recurring solutions to design problems
you see over

Design patterns constitute a set of rules describing how to
accomplish certain tasks in the realm of software development

Design patterns focus more on reuse of recurring
architectural design themes, while frameworks focus on
detailed design? and
implementation.

A pattern addresses a recurring design problem that arises
in specific design situations and presents a solution to it

Patterns identify and specify abstractions that are above
the level of single classes and instances, or of components

design pattern is a recurring solution to recurring problem 
in software architechture

Design patterns are higher level abstractions that define 
common software problems and  solutions to these 
problems.Their major importance: they enable  software 
developers to use best software practice , expertise and 
reusablity of good experiance with out ever doing the same 
problem agian  and again.

Design patterns are recurring solutions to recurring  
software problems. They make life easier for the software 
development by capturing the best expertise and experience 
of good practice of development.

I think the question is on Factory Method Pattern. So I 
will go in that direction. However there is another pattern 
called the Abstract Factory Pattern which is realted to 
Factory Method Pattern.

If we have to hide the "Creation" of an object and its 
Concrete type to a client, then the tendency is to 
use "Factory Method Pattern".

Normally a factory method is a method that is part of 
an "Abstract Factory". Client calls the factory method on 
an abstract factory which is a concrete object of an 
interface whose type may or may not be known to the client, 
to get a concrete object of the interface for product whose 
concrete type may or may not be useful to the client.

Use Adapter Pattern.

Make the constructor private

provide a static synchronized method to get the Instance.

this should make the object singleton for that jvm instance