CSE205 Lecture 07a

Object-Oriented Programming and Data Structures
Polymorphism
(202109)

Transcript

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   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
   

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   Previously…
   

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3. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 3
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   Inheritance
   § Constructors are not inherited
   § A child’s constructor is responsible for calling its parent’s constructor.
   § Keyword: super
   

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   Test Yourselves
   super
   

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5. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 5
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   Case 1
   # name:String
   + Vehicle()
   + Car()
   

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   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
   

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7. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 7
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   Person
   

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8. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 8
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   Student and Professor
   

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9. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 9
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   Main
   What is the output?
   

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10. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 10
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    Main
    

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11. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 11
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    Case 2: Make this work
    

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    Inheritance
    Override and Overload
    

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13. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 13
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    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.
    

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14. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 14
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    final
    

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15. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 15
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    final
    

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16. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 16
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    Method Overloading
    § The process of using the same name for multiple methods with different
    number or type of the parameters
    16
    

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17. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 17
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    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;
    }
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    Inheritance
    Abstract Classes and Interfaces
    

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19. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 19
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    We do not want to allow this
    

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20. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 20
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    Abstract Classes
    § cannot be instantiated and contains one or more abstract methods (no
    definition body).
    § can contain methods
    § can contain data declarations
    

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21. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 21
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    Abstract Classes
    

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22. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 22
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    Abstract Classes
    

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23. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 23
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    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.
    

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24. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 24
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    Abstract Methods
    

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25. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 25
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    Abstract Methods
    

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26. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 26
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    Questions
    

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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.
    

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