Question

I need a simple java program that contains all the following subjects :

1- OOP Objects -Classes

2- Encapsulation

3- Polymorphism

4-Inheritance

4- Abstract Classes

Answer 1

Please comment if you have any doubt

Code:

class Main1
{
   public int a=4,b=5;
   //Class Main1 is the Parent class
   void show1()
   {
       System.out.println("Main Class,a="+a+",b="+b);
   }
}
class One extends Main1
{
   //Class One is the child class of Main1
   void show()
   {
       System.out.println("Single Inheritence,a="+a+",b="+b);
   }
}
class Poly1{
   //Polymorphism means of more then one form
   //here a has two forms in Poly1 and Poly2
   int a=5;
}
class Poly2 extends Poly1{
   int a=10;
}
class Encapsule{
   private int a=5;
   //private is the key word used to encapsulate(hide) the data
   public int getA(){
       //getter methods are used to get data
       return a;
   }
}
class NewClass{
   //This is a OOP class
   void show(){
       System.out.println("This is a NewClass Object");
   }
}
abstract class Abs{
   //this is a abstract class for Abstraction
   //absract method must be defined in the child class
   abstract int add(int a,int b);
}
class Abs1 extends Abs{
   //method definition for abstract int add(int a,int b);
   int add(int a,int b){
       return a+b;
   }
}
public class MyClass{
   public static void main(String[] args) {
       //this is a OOP Object
       System.out.println("1- OOP Objects -Classes");
       NewClass obj=new NewClass();
       obj.show();

       //Encapsulation
       System.out.println("\n2- Encapsulation");
       Encapsule ens=new Encapsule();
       System.out.println(ens.getA());

       //Polymorphism
       System.out.println("\n3- Polymorphism");
       Poly1 poly=new Poly2();
       System.out.println(poly.a);

       //Inheritance
       System.out.println("\n4-Inheritance");
       One e=new One();
       e.show();

       //Abstract Classes
       System.out.println("\n5- Abstract Classes");
       Abs abs=new Abs1();
       System.out.println(abs.add(2,3));
   }
}

Screenshot:

class Main1 public int a=4,b=5; //Class Mainl is the Parent class void show1() System.out.println("Main Class, a="+a+", b="+b): class One extends Maini //Class One is the child class of Main1 void show) System.out.println("Single Inheritence, a="+a+", b="+b); class Polyl{ /Polymorphism means of more then one form //here a has two forms in Poly1 and Poly2 int a=5; class Poly2 extends Poly1{ int a=10; class Encapsule{ private int a=5; //private is the key word used to encapsulate(hide) the data public int getA() { //getter methods are used to get data return a; class NewClass{ //This is a OOP class void show(){ System.out.println("This is a NewClass Object"); abstract class Abs{ //this is a abstract class for Abstraction //absract method must be defined in the child class abstract int add(int a, int b); class Abs1 extends Abs{ //method definition for abstract int add(int a, int b); int add(int a, int b){ return a+b; 50 }

public class MyClass{ public static void main(String[] args) { //this is a OOP Object System.out.println("1- OOP Objects -Classes"); NewClass obj=new NewClass(); obj.show(); //Encapsulation System.out.println("n2- Encapsulation"); Encapsule ens=new Encapsule(); System.out.println(ens.getA()); //Polymorphism System.out.println("\n3 - Polymorphism"); Poly1 poly=new Poly2(); System.out.println(poly.a); //Inheritance System.out.println("\n4-Inheritance"); One e=new One(); e.show(); //Abstract Classes System.out.println("\n- Abstract Classes"); Abs abs=new Abs1(); System.out.println(abs.add(2,3)); 78 }

Output:

1- OOP Objects -Classes This is a Newclass Object 2- Encapsulation 3- Polymorphism 4-Inheritance Single Inheritence, a=4, b=5 5- Abstract Classes