In a project, the organization of the code as well as the clean code is very important, if the design of reasonable and clear classes will help a lot for expansion and maintenance later. To do this we need to have a truly reasonable Class Diagram design. So what is Class Diagram, let’s find out.
Definition of Class Diagram
- The class diagram describes the types of objects in the system and the various types of relationships that exist between them.
- As a modeling technique exists in all object-oriented development methods.
- Charts are most commonly used in UML and are closest to the programmers.
- Help programmers communicate with each other and understand each other’s ideas.
The basic properties of class diagrams
- Class name
- Attribute (field, property)
- Operation (method, function)
For example, declare the name, attribute, operation and return type of a class:
Access Modifier in class diagram
- Used to specify the scope of access for attributes and operations of a class (authorize other classes to use attributes and operations of this class).
- 4 selectable access ranges
- Private (-): Customize yourself objects created from this class can use.
- Public (+): Any object can use.
- Protected (#): Only objects created from this class and classes inheriting from this class can be used.
- Package / Default: Objects created from classes in the same package class can use them.
Relationship in class diagram
- Used to show each relationship between objects created from 1 class with objects created from other classes in the class diagram.
- 4 types of Relationship:
- Inheritance: A class inherits from another class.
- Association: 2 classes are related but do not specify a relationship.
- Composition: If object created from lass A loses object from class B will be lost.
- Agreegation: A class object is related to the other classB object, but if object B loses then object A is still normal.
Multiplicity in class diagram
- Used to show the number relationship between objects created from classes in the class diagram
- 0 … 1: 0 or 1
- n: Required n
- 0 … *: 0 or more
- 1 … *: 1 or more
- m … n: there is a minimum of m and a maximum of n
- The design of class diagrams is essential that a professional programmer must have.
- We hope your suggestions to improve themselves in the next article ❤️