JAVA QUESTION

Hi friend,

As per your problem

public class ConstructorOverloading{
public static void main(String args[]){
Rectangle rectangle1=new Rectangle(2,4);
int areaInFirstConstructor=rectangle1.first();
System.out.println(" The area of a rectangle in first constructor is : " + areaInFirstConstructor);

Rectangle rectangle2=new Rectangle(8,9,10);
int areaInTwoConstructor=rectangle2.first();
System.out.println(" The area of a rectangle in first constructor is : " + areaInTwoConstructor);

}
}
class Rectangle{
int l, b;
float p, q;
public Rectangle(int x, int y){
l = x;
b = y;
}
public int first(){
return(l * b);
}

public Rectangle(int i,int j,int k){

this(i,j);

}

}
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Ans 2.

Polymorphism :-

Polymorphism means the ability to take more than one form. Polymorphism means 'any forms.' In OOP, it refers to the capability of objects to react differently for the same method.

In OOP methodoverloading refers to the capability of objects to react differently for the same method. Polymorphism can be implemented in Java language in form of multiple methods having the same method name. Java code uses a late-binding for supporting polymorphism, the method which is invoked is decided at runtime.

In polymorphism by using a same function name with the different signature we can perform the multiple task this is called method overloading & using a same function name with the same signature we can extend the functionality of the superclass functions according to our requirement.

In java Polymorphism can be used in two ways :

1. Method Overloading

2. Method Overriding

1. Method Overloading :-
Overloaded methods are methods have the same name, but different argument lists.
Overloaded methods have the same names but different argument lists. The arguments may differ in type or number, or both. However, the return types of overloaded methods can be the same or different.

An example of the method overloading is given below:

class methodOverloading{
int add( int a,int b)
{
return(a+b);
}

float add(float a,float b)
{
return(a+b);
}
double add( int a, double b,double c)
{
return(a+b+c);
}
}
class mainClass extends methodOverloading
{
public static void main( String arr[] )
{
mainClass temp = new mainClass();
System.out.println(temp.add(10,20));
System.out.println(temp.add(1.5f,2.3f));
System.out.println(temp.add(10,20.4,25.6));
}
}

The output of the above program is given below:

30

3.8

56.0

2. Method Overriding :-
Overriding means when a subclass method has the same name, same return type, and same argument list as the superclass method.

class methodOverriding{
String showMessage(){
return("THIS IS SUPERCLASS METHOD");
}
}
class mainClass extends methodOverriding
{
public static void main( String arr[] )
{
String showMessage()
{
System.out.println("THIS IS SUBCLASS METHOD");
}
mainClass temp = new mainClass();
System.out.println(temp.showMessage());
}
}

The output of the above program is given below:

THIS IS SUBCLASS METHOD

Read for more information.


http://www.roseindia.net/java/learn-java-in-a-day/oops.shtml



Thanks.