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A short tutorial on using UML diagrams, particularly class diagrams, in object-oriented design.

Unified Modeling Language ("UML") is the industry standard"language"for describing, visualizing, and documenting object-oriented (OO) systems. UML is a collection of a variety of diagrams for differing purposes. Each type of diagram models a particular aspect of OO design in an easy to understand, visual manner. The UML standard specifies exactly how the diagrams are to be drawn and what each component in the diagram means. UML is not dependent on any particular programming language, instead it focuses one the fundamental concepts and ideas that model a system. Using UML enables anyone familiar with its specifications to instantly read and understand diagrams drawn by other people. There are UML diagram for modeling static class relationships, dynamic temporal interactions between objects, the usages of objects, the particulars of an implementation, and the state transitions of systems

In general, a UML diagram consists of the following features:

  • Entities : These may be classes, objects, users or systems behaviors.
  • Relationship Lines that model the relationships between entities in the system.
    • Generalization -- a solid line with an arrow that points to a higher abstraction of the present item.
    • Association -- a solid line that represents that one entity uses another entity as part of its behavior.
    • Dependency -- a dotted line with an arrowhead that shows one entity depends on the behavior of another entity.

Class diagrams

UML class diagrams model static class relationships that represent the fundamental architecture of the system. Note that these diagrams describe the relationships between classes , not those between specific objects instantiated from those classes. Thus the diagram applies to all the objects in the system.

A class diagram consists of the following features:

  • Classes : These titled boxes represent the classes in the system and contain information about the name of the class, fields, methods and access specifiers. Abstract roles of the class in the system can also be indicated.
  • Interfaces : These titled boxes represent interfaces in the system and contain information about the name of the interface and its methods.
  • Relationship Lines that model the relationships between classes and interfaces in the system.
    • Generalization
      • Inheritance : a solid line with a solid arrowhead that points from a sub-class to a superclass or from a sub-interface to its super-interface.
      • Implementation : a dotted line with a solid arrowhead that points from a class to the interface that it implement
    • Association -- a solid line with an open arrowhead that represents a"has a"relationship. The arrow points from the containing to the contained class. Associations can be one of the following two types or not specified.
      • Composition : Represented by an association line with a solid diamond at the tail end. A composition models the notion of one object"owning"another and thus being responsible for the creation and destruction of another object.
      • Aggregation : Represented by an association line with a hollow diamond at the tail end. An aggregation models the notion that one object uses another object without"owning"it and thus is not responsible for its creation or destruction.
    • Dependency -- a dotted line with an open arrowhead that shows one entity depends on the behavior of another entity. Typical usages are to represent that one class instantiates another or that it uses the other as an input parameter.
  • Notes that are used to provide further details or explanations of particular parts of the diagram. Notes are boxes with a little"dog-ear"on one corner.

Here is an example of a UML class diagram that holds most of the more common features:

Uml class diagram

The above diagram contains classes, interfaces, inheritance and implementation lines, aggregation lines, dependency lines and notes.

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Principles of object-oriented programming. OpenStax CNX. May 10, 2013 Download for free at http://legacy.cnx.org/content/col10213/1.37
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