CSE205 Lecture 07a

Object-Oriented Programming and Data Structures
Polymorphism
(202109)

Transcript

1. jgs CSE 205 Object-Oriented Programming and Data Structures Lecture 07: Inheritance II Dr. Javier Gonzalez-Sanchez javiergs@asu.edu javiergs.engineering.asu.edu | javiergs.com PERALTA 230U Office Hours: By appointment
2. jgs Previously…
3. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 3 jgs Inheritance § Constructors are not inherited § A child’s constructor is responsible for calling its parent’s constructor. § Keyword: super
4. jgs Test Yourselves super
5. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 5 jgs Case 1 # name:String + Vehicle() + Car()
6. jgs Javier Gonzalez-Sanchez | SER332 | Spring 2018 | 6 class Car extends Vehicle{ public Car(String n) { super (n); } } class Vehicle { protected String name; public Vehicle(String n) { name = n; } } Case 1
7. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 7 jgs Person
8. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 8 jgs Student and Professor
9. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 9 jgs Main What is the output?
10. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 10 jgs Main
11. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 11 jgs Case 2: Make this work
12. jgs Inheritance Override and Overload
13. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 13 jgs Method Overriding § A child class can override (redefine) the definition of an inherited method. (The new method must have the same signature.) § A method with the final modifier cannot be overridden. Warning: § Applied to variables final modifier makes them constant.
14. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 14 jgs final
15. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 15 jgs final
16. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 16 jgs Method Overloading § The process of using the same name for multiple methods with different number or type of the parameters 16
17. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 17 jgs Method Overloading public int calculate (int num1, int num2) { int sum = num1 + num2; return sum; } public int calculate (int num1, int num2, int num3) { int sum = num1 + num2 + num3; return sum; } 17
18. jgs Inheritance Abstract Classes and Interfaces
19. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 19 jgs We do not want to allow this
20. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 20 jgs Abstract Classes § cannot be instantiated and contains one or more abstract methods (no definition body). § can contain methods § can contain data declarations
21. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 21 jgs Abstract Classes
22. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 22 jgs Abstract Classes
23. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 23 jgs Abstract Methods § An abstract method is a method without a body. § It cannot be final or static because there is no definition, and it should be changed later.
24. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 24 jgs Abstract Methods
25. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 25 jgs Abstract Methods
26. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 26 jgs Questions
27. jgs CSE 205 Object-Oriented Programming and Data Structures Javier Gonzalez-Sanchez, Ph.D. javiergs@asu.edu Fall 2021 Copyright. These slides can only be used as study material for the class CSE205 at Arizona State University. They cannot be distributed or used for another purpose.