Encapsulation programming

8 Key excerpts on "Encapsulation programming"

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  Computer Programming NQF4 Student's Book

  TVET FIRST

  • S Sasti D Sasti(Author)
  • 2020(Publication Date)
  • Troupant

    (Publisher)

  Figure 1.7: Class diagram demonstrating OOP concepts (drawn with MS Visio) 9 Module 1 1.4.1 Encapsulation Definition: Encapsulation Encapsulation is an OOP property that refers to hiding the code and data in a single unit such as a class. Encapsulation is a process of preventing direct access to attributes from outside classes by using methods to control access to the attributes. The implementation of encapsulation creates a concept called information hiding . The data of the class is now protected against direct access from outside the class. Refer to clsAnimal from Figure 1.7 as we look at how to accomplish this. The steps are explained in Table 1.4. Table 1.4: Steps describing how encapsulation is implemented in Figure 1.7 Step 1 Declare the data members as private . This will ensure that they cannot be accessed directly from another class or its object. Remember ‘-’ means private . For example: - Colour: String - Weight: Decimal Step 2 Use public mutator methods to allow other classes or their objects to change the value of the data member. Remember ‘+’ means public . For example: + setColour(ByVal C_Value: String) + setWeight (ByVal W_Value: Decimal) Step 3 Use public accessor methods to allow other classes or their objects to access the value of the data member. For example: + getColour( ): String + getWeight (): Decimal Encapsulation in use VB.Net uses OOP and every control in the toolbox is a class. To use a control, we have to declare an object of that class. When we drag a control from the toolbox onto the form, VB.Net declares programmatically for us an object of that control. We then use the property window to set the properties for the control, such as name, text and font. We could do this in the code window as well. Some of these controls use encapsulation. Table 1.5 demonstrates encapsulation using VB.Net controls.

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  • Sameer S Paradkar(Author)
  • 2019(Publication Date)
  • BPB Publications

    (Publisher)

  Encapsulation: Data encapsulation is a key OO concept that facilitates binding code and data in a single translation unit called a class and hiding the implementation details from outside world. This prevents un-warranted access to data members and restricts the enduser to leverage the public methods of the class. Encapsulation implements one of the four fundamental OOP concepts, that is, data hiding. An object binds together the properties and methods that manipulate the data, which is safe from outside manipulations. Encapsulation is usually the process of hiding the elements from the outside world of an object that do not contribute to its key features.
• Abstraction: Abstraction is the mechanism of hiding unwanted details of an object from the outside world, and exposing just relevant details. The best example of abstraction is the interface. Encapsulation hides the unimportant details of an object from the outside world and abstraction makes just the relevant information of an object available to the outside world.
The following table compares abstraction and encapsulation:
Figure 6.7: Abstraction vs Encapsulation

Composition and inheritance

What are the types of inheritance?

Inheritance is an OO feature of a class to leverage the properties and methods of another class while adding its own features. It enables you to add fresh features and functionalities to an existing class without changing the existing class. There are four types of inheritance in OOPs:
• Single inheritance: This mechanism consists of one derived class and one base class. The following diagram depicts a single inheritance:
  Figure 6.8: Single inheritance
• Hierarchical inheritance: This mechanism consists of one base class and multiple derived classes from this base class.
• Multi-level inheritance: This mechanism consists of a class derived from a derived class.
• Multiple-inheritance: