mypg

package mypg;

import java.util.*;

public class Geometric {
private String color = "white";
private Date dateCreated;
public Geometric()
{
dateCreated = new Date();

}
public Geometric (String color)
{
this.color = color;
}
public void setColor(String color)
{
this.color = color;
}
public String getColor()
{
return this.color;
}
public Date getDate()
{
return dateCreated;
}
}

+++++++++++++++++++++++++++++++

package mypg;

public class Circle extends Geometric{

private double radius;

public Circle (double radius)

{

this.radius = radius;

}

public Circle(double radius,String color)

{

this.radius = radius;

setColor(color);

}

public double getArea()

{

return radius * radius * Math.PI;

}

}

+++++++++++++++++++++++++++++++++

package mypg;

public class Test {

public static void main(String[] args) {

Geometric geo1 = new Geometric();

System.out.println(geo1.getColor()+" ; "+geo1.getDate());

Circle cir1 = new Circle(4);

cir1.setColor("red");

System.out.println(cir1.getColor()+ " ; " +cir1.getDate() + " ; " +cir1.getArea());

}

}

Polymorphism

nแปลว่า หลายรูปทรง แปลงสภาพได้

Example

class CustomerData{

   protected void CustomerPhone(){

        System.out.println(“02 123 456”);

   {

   protect void ClearAll(){

        System.out.println(“Delete All Data”);

   }

}

+++++++++++++++++++++++++++++++++++++++++ๅๅๅๅ

เวลาเรียกใช้

class CustomerData2 extends CustomerData {

   protected void CustomerPhone(){

         super.CustomerPhone();

         System.out.println(“02 123 456 7”);

   {

   protect void ClearAll(){

   }

}

Inheritance

nแปลว่า การสืบสันดาน หรือ การสืบมรดก

nต่อยอดงานใหม่ จากงานเก่าไม่ต้องเริ่มจากศูนย์

nภาษา OOP สนับสนุน Inheritance เสมอ

Example

class Foo{

   public void WriteFoo(){

      System.out.println(“Foo”);

   }

}

class Bar extends Foo{

   public void WriteBar(){

      System.out.println(“Bar”);

   }

}

+++++++++++++++++++++++++++++++++++++++++ๅ

เวลาเรียกใช้

class Program{

   public static void main (String[] args){

      Bar myBar = new Bar();

      myBar.WriteFoo();

      myBar.WriteBar();

   }

} 

Overloaded Constructor

nเป็นคอนสตรัคเตอร์กำหนดเอง

nคอนสตรัคเตอร์ทุกตัวชื่อเหมือนกับคลาส

nทำการรับพารามิเตอร์ไม่เหมือนกัน

class Calculator{

  Calculator(int x){

  return x + x;}

   Calculator(int x, int y){

  return x + y;}  

   Calculator(int x, int y, int z){

  return x + y + z;}

}

เวลาเรียกใช้คอนสตรัคเตอร์

class TestCalculator{

  public static void main(String[] args) {

  Calculator a = new Calculator();

  System.out.println(a.Calculator(1));

 

  Calculator b = new Calculator();  

  System.out.println(b.Calculator(1, 2));

  Calculator c = new Calculator();

  System.out.println(c.Calculator(1, 2, 3));

  }

}

โอเวอร์โหลดเมธอด

public class TestOver1 {

  public static int add() {

  return 0;       }

  public static int add(int x) {

  return x;      }

  public static int add(int x, int y)   {

  return x+y;               }

  public static int add(int x, int y, int z) {

  return x+y+z;                      }


เวลาเรียกใช้เมธอด

  public static void main(String[] args)                   
{

  System.out.println("Sum = "+add());

  System.out.println("Sum = "+add(3));

  System.out.println("Sum = "+add(1,2));

  System.out.println("Sum = "+add(1,2,3)); }

}

Test_java2

TV

package

java_1;

public

class TV {

private int chanel = 1;//1-10

private int volume = 1;//0-5

private boolean status = false;// By default TV is off

private String brand = "";

public static int count = 0;

TV(){

count++;

brand = "Sony";

}

TV(String newBrand){

count++;

brand = newBrand;

}

TV(String newBrand,

int newchanel){

count++;

brand = newBrand;

chanel = newchanel;

}

public String getBrand(){

return brand;

}

public void turnOn(){

//Mutator of status variable

status = true;

}

public void turnOff(){

//Mutator of status variable

status = false;

}

public boolean getStatus(){

//Accessor of status variable

return status;

}

public void chanelUp(){

chanel++;

if(chanel > 10){

chanel = 1;

}

}

public void chanelDown(){

chanel--;

if(chanel < 1){

chanel = 10;

}

}

public int getChanel(){

if(status == false)

{

System.

out.println("Please TurnOn TV");

return 0;

}

else

return chanel;

}

public void volumeUp(){

if(volume < 5)

volume++;

else

System.

out.println("Maximum");

}

public void volumeDown(){

if(volume > 0)

volume--;

else

System.

out.println("Minimum");

}

public int getVolume(){

return volume;

}

public boolean equalsTV(TV o){

if(o.getChanel() != this.getChanel())

return false;

if(o.getStatus() != this.getStatus())

return false;

if(o.getVolume() != this.getVolume())

return false;

return true;

}

}