Class Diagram

      A class diagram is an illustration of the relationships and source code dependencies among classes in the Unified Modeling Language (UML). In this context, a class defines the methods and variables in an object, which is a specific entity in a program or the unit of code representing that entity.

In a class diagram, the classes are arranged in groups that share common characteristics. A class diagram resembles a flowchart in which classes are portrayed as boxes, each box having three rectangles inside. The top rectangle contains the name of the class; the middle rectangle contains the attributes of the class; the lower rectangle contains the methods, also called operations, of the class. Lines, which may have arrows at one or both ends, connect the boxes. These lines define the relationships, also called associations, between the classes.

So the purpose of the class diagram can be summarized as:

- Analysis and design of the static view of an application.

- Describe responsibilities of a system.

- Base for component and deployment diagrams.

- Forward and reverse engineering.

      Class diagrams are the most popular UML diagrams used for construction of software applications. So it is very important to learn the drawing procedure of class diagram. Class diagrams have lot of properties to consider while drawing but here the diagram will be considered from a top level view. Class diagram is basically a graphical representation of the static view of the system and represents different aspects of the application. So a collection of class diagrams represent the whole system.

Class

 A class represents an entity of a given system that provides an encapsulated implementation of certain functionality of a given entity. These are exposed by the class to other classes as methods. Apart from business functionality, a class also has properties that reflect unique features of a class. The properties of a class are called as attributes. The UML representation of a class is a rectangle containing three compartments stacked vertically

Association

An association represents a relationship between two classes. An association indicates that objects of one class have a relationship with objects of another class, in which this connection has a specifically defined meaning.

This is the example of class diagram about blog system:

Mengelola Comment

(addComment, viewComment, replyComment)

Attribute     : isi_comment, tgl_comment, panjang_isiComment, email

Operation   : set_isiComment, get_isiComment, set_tglComment, get_tglComment

Mengelola Profil

(addNewProfil, editProfil)

Attribute     : id_profil, nama_profil, email

Operation   : set_idProfil, set_namaAdmin, get_namaAdmin

Mengelola Template

(editHtml, cadangkan/pulihkan)

Attribute     : isi_html

Operation   : set_isiHtml, get_isiHtml

Mengelola Posting
(inputNewPosting, editPosting, deletePosting, viewPosting)

Attribute     : isi_posting, tgl_posting, panjang_isiPosting

Operation   : set_isiPosting, get_isiPosting, set_tglPosting, get_tglPosting

Mengelola Layout

(addGadget, editGadget, deleteGadget)

Attribute     : isi_gadget

Operation   : set_isiGadget, get_isiGadget

Monetize Blog

(approveIklan)

Attribute     : id_iklan, email, isi_iklan, tgl_iklan

Operation   : get_idIklan, set_isiIklan, get_isiIklan, set_tglIklan, get_tglIklan