CSE205 Lecture 18

Object-Oriented Programming and Data Structures
Generics
(202204)

Transcript

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   CSE 205
   Object-Oriented Programming and
   Data Structures
   Lecture 18: Generic-Data Types
   Dr. Javier Gonzalez-Sanchez
   javiergs@asu.edu
   javiergs.engineering.asu.edu | javiergs.com
   PERALTA 230U
   Office Hours: By appointment
   

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   Midterm Exams
   

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   Previously …
   

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4. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 13
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   Program.java
   

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5. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 14
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   Class MyList
   

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6. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 15
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   Class MyNode
   

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7. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 16
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   I introduce you a List, a Linked List
   

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8. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 17
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   insertFirst()
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   newNode
   

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9. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 18
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   insertAt()
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   newNode
   

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10. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 19
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    deleteFirst()
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11. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 20
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    deleteLast()
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12. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 21
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    get (index)
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    Generics
    Parametrized Data Types
    

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14. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 23
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    Definition
    § Generics or parameterized types.
    § The idea is to allow type (Integer, String, … etc., and user-defined types) to
    be a parameter to methods, classes, and interfaces.
    § Using Generics, it is possible to create classes that work with different data
    types.
    § An entity such as class, interface, or method that operates on a
    parameterized type is called a generic entity.
    

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15. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 24
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    Case 1
    class Test {
    T obj;
    Test(T obj) {
    obj = obj;
    }
    public T getObject() {
    return obj;
    }
    }
    class Main {
    public static void main(String[] args) {
    Test iObj = new Test(15);
    System.out.println(iObj.getObject());
    Test sObj = new Test("Hello World!");
    System.out.println(sObj.getObject());
    }
    }
    // we can not use primitives like int, char or double.
    

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16. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 25
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    Case 2
    public class GenericMethodTest {
    public static void printArray( E[] inputArray ) {
    for(int i=0; iSystem.out.print(""+ inputArray[i]);
    }
    System.out.println();
    }
    public static void main(String args[]) {
    Integer[] intArray = { 1, 2, 3, 4, 5 };
    Double[] doubleArray = { 1.1, 2.2, 3.3, 4.4 };
    Character[] charArray = { 'H', 'E', 'L', 'L', 'O' };
    System.out.println("Array integerArray contains:");
    printArray(intArray);
    System.out.println("\nArray doubleArray contains:");
    printArray(doubleArray);
    System.out.println("\nArray characterArray contains:");
    printArray(charArray);
    }
    }
    

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17. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 26
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    Case 3
    class Test {
    T obj1; // An object of type T
    U obj2; // An object of type U
    Test(T obj1, U obj2) {
    this.obj1 = obj1;
    this.obj2 = obj2;
    }
    public void print() {
    System.out.println(obj1);
    System.out.println(obj2);
    }
    }
    class Main {
    public static void main (String[] args) {
    Test obj = new Test(”ABC", 15);
    obj.print();
    }
    

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18. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 27
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    Generic Data Types
    

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19. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 28
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    Generic Data Types
    

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20. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 29
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    Generic Data Types
    

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21. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 30
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    Questions
    

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    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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