Visibility in Class Diagram - Explained
In the next video, you will be introduced to concept of the visibility of the methods and attributes of a class.
In the previous video, you learnt about visibility, which is also called access specifier, as it specifies how attributes and methods of a class will be accessed by different classes.
Visibility is mainly of two types:
- Public (+) = Attributes and methods that are marked 'public' can be accessed from within or outside that class.
- Private (-) = Attributes and methods that are marked 'private' can be accessed only from within that class.
Video Transcript
We'll now see about how to represent the visibility of the methods and attributes of the class. In terms of visibility, we are largely aware of two major visibilities, which is public and private. They are also commonly called as access specifiers and method. Or an attribute of a class can be either public or private. When we say public, it's accessible across, while we say it's private, only the methods are within the class it is accessible. So if an attribute or a method is public, we represent it using a plus symbol before the method name or the attribute name. Similarly, private methods and attributes are prefixed with a minus before them. So let's take an example of a public and private representation in our order class. In case of order, an order could contain multiple items and different quantities. So if I have to get the total cost of an order, that could be a public method. In contrary, for a given order, if I need to check with my supplier, I can have a method called check supplier, but that need not be public. So a check with supplier method can be marked as private, so that could be prefixed with a minus.
Video Recap
The segment explains how to represent the visibility of methods and attributes of a class in programming.
There are two major visibilities: public and private (also called access specifiers).
Public methods and attributes are accessible across the program, while private ones are only accessible within the class they are defined in.
Public methods and attributes are represented with a plus symbol, while private ones are represented with a minus symbol.
An example is given with an order class, where the total cost of an order is a public method, while a method to check with the supplier is a private method.
Marking methods and attributes as private can help to control access and protect sensitive information.
By using access specifiers, programmers can better organize and structure their code to improve readability and maintainability.
So far, you have learnt about class, attributes, methods and visibility. In the next video, you will see how to draw a class and its components in draw.io.
In the previous video, you saw how to draw a class and its components in draw.io. You also assigned visibility to different componenets.
Now you are familiar with the representation of the access modifiers in the Class Diagram. Access modifiers define the visibility of an attribute/method. Private attributes and methods are only visible inside the class, whereas public attributes and methods are visible outside the class also.