WAP to calculate square

/*WAP to calculate square*/

import java.lang.*;
class sqr
{
 int n,sqr;
 sqr(int n1)
  {
   n=n1;
  }
 void calculate()
    {
     sqr=n*n;
    }
 void display()
    {
     System.out.println("squar=" + sqr);
    }
}
class demo_sqr
{
 public static void main(String arg[])
   {
   sqr s1=new sqr(3);
   s1.calculate();
   s1.display();
   }
}