Object-oriented (OO) Basics and principles

Object-oriented basics:

OO Basics	Understanding	Implementation Method
Encapsulation	Encapsulate objective things into abstract classes, and classes can only allow trusted classes or object operations for their own data and methods to hide untrusted information.
Inheritance	You can use all the functions of an existing class and extend these functions without re-writing the original class.	Inheritance concepts can be implemented in three ways: Implementation inheritance, interface inheritance, and visual inheritance.
Polymorphism	The technology that sets a parent object to be equal to one or more other sub-objects. After a value is assigned, the parent object can operate in different ways based on the features assigned to its sub-objects.	There are two methods to achieve polymorphism: overwrite and reload.

Object-oriented principle:

OO principles	Understanding
Single Responsibility Principle	For a class, there should be only one reason for its change.
Open-closed Principle	Class should be open to the extension and closed with multiple modifications
Liskov replacement principle	Subclass should be able to replace the parent class and appear anywhere the parent class can appear.
Dependency inversion principle
Interface isolation principle	Using multiple interfaces related to a specific customer class is better than using a common interface that covers multiple business methods.