Static Data members

  class Circle 
  {
    private int R;
    private static double Pi=3.14;
    public void area()
    {
        double a=Pi*R*R;
        System.out.println("Area is "+a);
    }
    public Circle(int n)
    {
        R=n;
    }
  } 
  class demo
  {
    public static void main(String args[])
    {
        Circle a=new Circle(5);
        Circle b=new Circle(3);
        Circle c=new Circle(2);
        a.area();
        b.area();
        c.area();
    }
  }

  class Account 
  {
    private int accno,balance;
    private static double irate=10.25;
    public void interest(int n)
    {
        double si=balance*irate*n/100;
        System.out.println("Interest is "+si);
    }
    public Account(int an,int bl)
    {
        accno=an;
        balance=bl;
    }
  }
  class demo
  {
    public static void main(String args[])
    {
        Account a=new Account(4117,25000);
        Account b=new Account(3012,10000);
        a.interest(5);
        b.interest(2);
    }
  }

  class Student 
  {
    private int rollno;
    private String name;
    public static int count;
    public void showData()
    {
        System.out.print("RollNo is "+rollno);
        System.out.println("Name is "+name);
    }
    public Student(int r,String n)
    {
        rollno=r;
        name=n;
        count=count+1;

    }
  }
  class demo
  {
    public static void main(String args[])
    {
        System.out.println("Total Students: "+Student.count);
        Student a=new Student(4117,"Amit Jain");
        Student b=new Student(3012,"Seeta Rathi");
        System.out.println("Total Students:"+Student.count);
        Student c=new Student(5123,"Raja Rao");
        System.out.println("Total Students:"+Student.count);
        a.showData();
        b.showData();
        c.showData();
    }
  }