Packages and Interfaces in java

$$Packages & Interfaces in java




package my_package;
import java.util.Scanner;
interface perimeter1
{
void calculate();
}
class circle1 implements perimeter1
{
private double r;
public void calculate()
{
System.out.println("Enter radius:");
Scanner input=new Scanner(System.in);
double r=input.nextDouble();
double p=2*3.14*r;
System.out.println("perimeter of circle is:- "+p);
}
}
class rectangle1 implements perimeter1
{
private double length,breadth;
public void calculate()
{
System.out.println("Eneter length");
Scanner input=new Scanner(System.in);
double length=input.nextDouble();
System.out.println("Eneter breadth");
double breadth=input.nextDouble();
double p=2*(length+breadth);
System.out.println("perimeter of rectangle is:- "+p);

}
}
class main1
{
public static void main(string args[])
{
perimeter1 obj;
circle1 obj1=new circle1();
rectangle1 obj2=new rectangle1();
System.out.println("\n\t Calculating perimeter of circle...\n");
obj=obj1;
obj.calculate();
System.out.println("\n\t Calculating perimeter of rectangle...\n");
obj=obj2;
obj.calculate();
}
}
/*
  Calculating perimeter of circle...

Enter radius:
6
perimeter of circle is:- 37.68

Calculating perimeter of rectangle...

Eneter length
4
Eneter breadth
6
perimeter of rectangle is:- 20.0

Process completed.
*/