Inheritance Class Hierarchies SoftUni Team Technical Trainers Software University

2 1.Fundamental Principles of OOP 2.Inheritance ▪ Class Hierarchies ▪ Inheritance and Access Levels Table of Contents

3 sli.do #3666 Questions

Fundamental Principles of OOP

▪Encapsulation ▪Inheritance ▪ Inherit members from parent class ▪ Inherit constructors from parent class ▪ Polymorphism ▪ Abstraction Fundamental Principles of OOP 5

Inheritance

Types of Inheritance derived class base class / parent class inherits 7

Types of Inheritance (2) interface class implements 8

Types of Inheritance (3) derived interface base interface extends 9

1. Extensibility 2. Reusability 3. Provides abstraction Inheritance – Benefits 10

Don't use it to build has-a relationship E.g. dog has-a name (dog is not a name) Examples - Incorrect 11

Use inheritance for building is-a relationship E.g. dog is-a animal (dog is an animal) Examples - Correct 12

13 How to Define Inheritance? class DerivedClass extends BaseClass

14 Use super to invoke the parent constructor How to Define Inheritance? (2) public Circle(int x, int y) { super(x, y); }

Exercises in Class

16 Private members are hidden Inaccessible Members

17 Inheritance – Example Person +Name: string +Address: string Employee +Company: string +Salary: decimal Student +School: string Base class Derived class

Class Hierarchies Game MultiplePlayersGame BoardGame Chess Backgammon SinglePlayerGame Minesweeper Solitaire 18

Simple Inheritance Live Demo

20 ▪ public ▪ private ▪ protected ▪no modifier Access Modifiers in Java

21 There is no multiple inheritance Inheritance: Important Aspects

22 Constructors are not inherited Inheritance: Important Aspects (2)

23 Extended class could add new members, but couldn’t remove derived members Inheritance: Features

24 New members with the same name or signature hide the inherited ones Inheritance: Features (2)

Exercises in Class

26 UML class diagrams Inheritance Hierarchies

27 UML Class Diagram – Example

Class Diagrams in IntelliJ Idea Live Demo

29 ▪Inheritance allows extending the behavior of the classes ▪ Inheriting Fields ▪ Inheriting Methods ▪ Reusing the existing code Summary

? ? ? ? ? ? ? ? ? OOP – Encapsulation

License ▪ This course (slides, examples, demos, videos, homework, etc.) is licensed under the "Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International" licenseCreative Commons Attribution- NonCommercial-ShareAlike 4.0 International 31 ▪ Attribution: this work may contain portions from ▪ "Fundamentals of Computer Programming with Java" book by Svetlin Nakov & Co. under CC-BY-SA licenseFundamentals of Computer Programming with JavaCC-BY-SA ▪ "OOP" course by Telerik Academy under CC-BY-NC-SA licenseOOPCC-BY-NC-SA

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