Calculate Average Of 'N' Numbers Using Java Program

        /*  AVERAGE CALCULATION OF 'N' NUMBERS  */

import java.io.*;
import java.text.*;

class ssva17
{
    public static void main(String arg[]) throws IOException
    {
        int i,n;
        double a[]=new double[20];
        double tot=0,avg;
        BufferedReader obj=new BufferedReader(new InputStreamReader(System.in));
        System.out.println(" AVERAGE CALCULATION ");
        System.out.println(" ------- ----------- ");
        System.out.print("\nENTER HOW MANY NUMBERS : ");
        n=Integer.parseInt(obj.readLine());
        NumberFormat nf=NumberFormat.getInstance();
        nf.setMaximumFractionDigits(2);
        nf.setMinimumFractionDigits(2);
        System.out.println("\nENTER THE NUMBERS\n");
        for(i=1;i<=n;i++)
        {
            a[i]=Double.parseDouble(obj.readLine());
            tot+=a[i];
        }
        System.out.println("\nTOTAL IS : "+nf.format(tot));
        avg=tot/n;
        System.out.println("\nTHE AVERAGE IS : "+nf.format(avg));
        System.out.println("\n");
    }
}