FINDING AREA PERIMETER OF A CIRCLE PROGRAM IN JAVA

import java.util.*;
class circle
{
public static void main (string args[])
{
float a,p,r;
final ob=new scanner (system.in);
system.out.println("enter radius of circle :");
r= ob next float ();
a= pi *r*r;
p= 2*pi*r;
system.out.println("area of circle :" +A);
system.out.println("perimeter of circle :" +i);
}
}