CSE205 Lecture 18

Object-Oriented Programming and Data Structures
Generics
(202204)

Transcript

1. jgs 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
2. jgs Midterm Exams
3. jgs Previously …
4. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 13 jgs Program.java
5. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 14 jgs Class MyList
6. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 15 jgs Class MyNode
7. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 16 jgs I introduce you a List, a Linked List
8. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 17 jgs insertFirst() null head newNode
9. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 18 jgs insertAt() null head newNode
10. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 19 jgs deleteFirst() null head
11. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 20 jgs deleteLast() null head
12. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 21 jgs get (index) null head
13. jgs Generics Parametrized Data Types
14. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 23 jgs 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.
15. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 24 jgs Case 1 class Test<T> { T obj; Test(T obj) { obj = obj; } public T getObject() { return obj; } } class Main { public static void main(String[] args) { Test<Integer> iObj = new Test<Integer>(15); System.out.println(iObj.getObject()); Test<String> sObj = new Test<String>("Hello World!"); System.out.println(sObj.getObject()); } } // we can not use primitives like int, char or double.
16. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 25 jgs Case 2 public class GenericMethodTest { public static <E> void printArray( E[] inputArray ) { for(int i=0; i<inputArray.length;i++) { System.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); } }
17. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 26 jgs Case 3 class Test<T, U> { 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 <String, Integer> obj = new Test<String, Integer>(”ABC", 15); obj.print(); }
18. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 27 jgs Generic Data Types
19. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 28 jgs Generic Data Types
20. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 29 jgs Generic Data Types
21. Javier Gonzalez-Sanchez | CSE205 | Fall 2021 | 30 jgs Questions
22. 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.