Wednesday, December 22, 2010

Java-Inheritance



---Rectangle.class---

public class Rectangle {
 private int length = 0;
 private int breadth = 0;
 public Rectangle() {
 }
 public Rectangle(int value) {
  length = value;
  breadth = value;
 }
 public Rectangle(int length, int breadth) {
  this.length = length;
  this.breadth = breadth;
        }
 public int getLength() {
  return length;
 }
 public int getBreadth() {
  return breadth;
 }
 public void setLength(int length) {
  this.length = length;
        }
 public void setBreadth(int breadth) {
  this.breadth = breadth;
        }
 public int calcArea() {
  return length * breadth;
        }
}


---TestRectangle.class---

class TestRectangle {
 public static void main(String[] args) {
  Rectangle r1 = new Rectangle();
  System.out.println("r1 Length: " + r1.getLength()); // 0
  System.out.println("r1 Breadth: " + r1.getBreadth()); // 0
  System.out.println("r1 Area: " + r1.calcArea()); // 0
  System.out.println("-----------------------------------------");

  Rectangle r2 = new Rectangle(10);
  System.out.println("r2 Length: " + r2.getLength()); // 10
  System.out.println("r2 Breadth: " + r2.getBreadth()); // 10
  System.out.println("r2 Area: " + r2.calcArea()); // 100
  System.out.println("-----------------------------------------");

  Rectangle r3 = new Rectangle(10, 20);
  System.out.println("r3 Length: " + r3.getLength()); // 10
  System.out.println("r3 Breadth: " + r3.getBreadth()); // 20
  System.out.println("r3 Area: " + r3.calcArea()); // 200
  System.out.println("-----------------------------------------");

  r1.setLength(100);
  r1.setBreadth(200);
  System.out.println("r1 Length: " + r1.getLength()); // 100
  System.out.println("r1 Breadth: " + r1.getBreadth()); // 200
  System.out.println("r1 Area: " + r1.calcArea()); // 20000
 }
}

---Container.class---

public class Container extends Rectangle {
 private int height = 0;

 public Container() {
  super(0);
 }
 public Container(int value) {
  super(value);
  height = value;
 }
 public Container(int length, int breadth, int height) {
  super(length, breadth);
  this.height = height;
 }
 public void setHeight(int height) {
  this.height = height;
 }
 public int getHeight() {
  return height;
 }
 public int calcVolume() {
  return calcArea() * height;
 }
}



---TestContainer.class---

class TestContainer {
 public static void main(String[] args) {
  Container c1 = new Container();
  System.out.println("c1.getLength(): " + c1.getLength()); //0
  System.out.println("c1.getBreadth(): " + c1.getBreadth()); //0
  System.out.println("c1.getHeight(): " + c1.getHeight()); //0
  System.out.println("c1.calcArea(): " + c1.calcArea()); //0
  System.out.println("c1.calcVolume(): " + c1.calcVolume()); //0
  System.out.println("----------------------------------------");

  Container c2 = new Container(10);
  System.out.println("c2.getLength(): " + c2.getLength()); //10
  System.out.println("c2.getBreadth(): " + c2.getBreadth()); //10
  System.out.println("c2.getHeight(): " + c2.getHeight()); //10
  System.out.println("c2.calcArea(): " + c2.calcArea()); //100
  System.out.println("c2.calcVolume(): " + c2.calcVolume()); //1000
  System.out.println("----------------------------------------");

  Container c3 = new Container(10, 20, 30);
  System.out.println("c3.getLength(): " + c3.getLength()); //10
  System.out.println("c3.getBreadth(): " + c3.getBreadth()); //20
  System.out.println("c3.getHeight(): " + c3.getHeight()); //30
  System.out.println("c3.calcArea(): " + c3.calcArea()); //200
  System.out.println("c3.calcVolume(): " + c3.calcVolume()); //6000
 }
}



Rectangle r = new Container(10, 20, 30); /*valid
because where ever a class (instance) is expected, we can pass its instance or the instance of its direct or indirect subclass*/
Container c = new Rectangle(10, 20); /*invalid
because of the reason above; Here class Rectangle is the super class of class Container*/






0 comments:

Post a Comment

Contact Form

Name

Email *

Message *

The Insane Techie - Android App

Launched an android app for the blog on 07th June 2016. Get it from google play store... Tips for using the app Use in landscape mo...