Java Programming Language Mr.Rungrote Phonkam

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1 8 Java Programming Language Mr.Rungrote Phonkam

2 Contents 1. Package 2. Access Level 3. Inheritance 4. super vs this 5. Polymorphism

3 1. Package ก ก (Package) ก ก ก ก ก ก ก Bytecodes ก ก ก ก ก ก ก ก ก ก ก

4 1. Packages class A { a.java A.class class A { class B { A.class a.java B.class

5 ก ก ก package Package_Name package Pkg1; public class A { package Package_Name 1. Package ก ก ก ก

6 1. Package c:\myjava>javac -d. a.java myjava A.java pkg1 C A.class

7 1. Package package Exchange; public class Temperature { public static float F2C(float f) { return ((f-32) * 5.0F) / 9.0F; public static float C2F(float c) { return (c * 9.0F/5.0F) F;

8 1. Package myjava Temperature.java Exchange C Temperature.class

9 ก ก ก import Package_Name.Class_Name 1. Package import ก ก ก ก ก Package_Name ก ก (ก ก ก ) Class_Name ก ก ก CLASSPATH import Pkg1.A; public class A {

10 1. Package import Exchange.Temperature; class CalTemp { public static void main(string args[]) { float t = Float.parseFloat(args[0]); System.out.print(args[0] + " Degree Centigrade = "); System.out.print(Temperature.C2F(t)); System.out.println(" Degree Fahrenheit"); java CalTemp Degree Centigrade = 89.6 Degree Fahrenheit

11 1. Package myjava Exchange Temperature.java import caltemp.java C Temperature.class C caltemp.class

12 1. Package package ConsoleInput; import java.io.*; public class KeyboardInput { public static String readtext() { String name = ""; BufferedReader inreader = new BufferedReader(new InputStreamReader(System.in)); try { name = inreader.readline(); catch(exception e) { e.printstacktrace(); finally { return name;

13 1. Package myjava Temperature.java Temperature.class C Exchange KeyboardInput.java ConsoleInput C KeyboardInput.class

14 1. Package import ConsoleInput.KeyboardInput; import Exchange.Temperature; class ExecTemp { public static void main(string args[]) { int t; System.out.print("Enter Degree Cencert Temperature: "); t = Integer.parseInt(KeyboardInput.readText()); System.out.println(t + " Degree Conceit = " + Temperature.C2F(t) + " Farenheigh"); java ExecTemp Enter Degree Cencert Temperature: Degree Conceit = Farenheigh

15 1. Package myjava Temperature.java Exchange C Temperature.class KeyboardInput.java import import ConsoleInput C ExecTemp.java KeyboardInput.class C ExecTemp.class

16 2. Access Level ก (Accessibility/ Access Level) ก ก ก Information Hiding ก 4 private, package, protected public ก ก Data Member Method Member ก ก ก ก ก

17 private ก 2. Access Level ก ก ก ก ก ก ก / ก private

18 package ก 2. Access Level ก ก ก ก ก ก ก / ก package(default)

19 2. Access Level protected ก ก ก ก ก ก ก ก / ก protected

20 public ก 2. Access Level ก ก ก ก ก ก ก / ก public

21 3. Inheritance ก ก Data Method ก ก ก Data Method ก Subclass Extend Class ก Super Class ก กก Reusability Object Oriented ก ก ก ก ก ก

22 3. Inheritance ก ก ก Inheritance Class Subclass Super Class

23 class Subclass extends Super_Class { Data_Member; Method_Member; 3. Inheritance Subclass Super_Class ก extends ก ก Data _Member Method_Member

24 3. Inheritance Super Class class Sheet { private int page = 0; private String article; public String size; Sheet() { article = ""; size = "A4"; Sheet(String a) { article = a; Sheet(String a, int p) { article = a; page = p; protected void addpage(int p) { page += p; protected int getpage() { return page; protected void printsummary() { System.out.println( article + " Contains " + page + " Pages")

25 3. Inheritance class Magazine1 extends Sheet { String name = "" ; int issue, year; Magazine1(String t, int is, int y) { name = t; issue = is; year = y; void printmagazine() { System.out.println("Magazine Name: " + name); System.out.println("Issue: " + issue + " Year: " + year); System.out.println("\tPage: " + getpage( ) ); class KidMag { public static void main(string arg[]) { Magazine1 mag = new Magazine1("Child Worlds", 5, 2000); mag.addpage(20); mag.printmagazine();

26 3. Inheritance java KidMag Magazine Name: Child Worlds Issue: 5 Year: 2000 Page: 20

27 3. Inheritance class Magazine2 extends Sheet { Stringname=""; public String size = ""; // Duplicate Name in Super Class int issue, year; Magazine2(String t, int is, int y) { name = t; issue = is; year = y; protected void printsummery() // Duplicate Name in Super Class { System.out.println( "Magazine Name: " + name); System.out.println( "Issue: " + issue + " Year: " + year); System.out.println( "Size:" + size); class AdultMag { public static void main(string arg[]) { Magazine2 mag = new Magazine2("Car Racing", 16, 2020); mag.addpage(20); mag.size = "Short A4"; mag.printsummery();

28 3. Inheritance java AdultMag Magazine Name: Car Racing Issue: 16 Year: 2020 Size: Short A4

29 4. super vs this super vs this กก data method ก super class sub class ก data method super class super sub class ก data method sub class this data method sub class

30 4. super vs this data data super.data Super class super.method this.method this.data Super class

31 4. super vs this class Magazine3 extends Sheet { Stringname=""; public String size = ""; // Duplicate Name in Super Class int issue, year; Magazine2(String t, int is, int y) { name = t; issue = is; year = y; protected void printsummery() // Duplicate Name in Super Class { System.out.println( "Magazine Name: " + name); System.out.println( "Issue: " + issue + " Year: " + year); System.out.println( "Size:" + super.size); class AdultMag { public static void main(string arg[]) { Magazine2 mag = new Magazine2("Car Racing", 16, 2020); mag.addpage(20); mag.size = "Short A4"; mag.printsummery();

32 4. super vs this java AdultMag Magazine Name: Car Racing Issue: 16 Year: 2020 Size: A4

33 4. super vs this class Magazine3 extends Sheet {. protected void printsummery() { System.out.println( "Magazine Name: " + name); System.out.println( "Issue: " + issue + " Year: " + year); System.out.println( "Size:" + this.size);....

34 5. Polymorphism ก ก ก Super Class Sub Class ก Data Method Super Class Sub Class

35 5. Polymorphism class WomanMag { static void printofmag1(sheet m) { m.printsummery(); static void printofmag2(sheet m) { m.printsummery(); public static void main(string arg[]) { Sheet obj1 = new Magazine1("Thai Food Cooking", 2, 2543); Sheet obj2 = new Magazine2("How to Shopping", 2120, 2545); printofmag1(obj1); System.out.println(" "); printofmag2(obj2);

36 5. Polymorphism java WomanMag Contains 0 Pages Magazine Name: How to Shopping Issue: 2120 Year: 2545 Size:

37 5. Polymorphism Magazine1 obj1 Sheet Magazine2 obj2 Sheet printsummery

Arrays Classes & Methods, Inheritance

Course Name: Advanced Java Lecture 4 Topics to be covered Arrays Classes & Methods, Inheritance INTRODUCTION TO ARRAYS The following variable declarations each allocate enough storage to hold one value