JAVA Help

import java.util.*;
class happy
{
    public static void main()
    {
        Scanner s=new Scanner(System.in);
        int n,x,sum,i,digit;
        System.out.println("enter a no.");
        n=s.nextInt();
        if(n==1||n==7)
        System.out.println("happy no.");
        for(x=n;x>=10;x=sum)
        {
            sum=0;
            i=x;
            while(i>0)
            {
                digit=i%10;
                sum=sum+digit*digit;
                i=i/10;
            }
        }
        if(x==1)
        System.out.println("happy no.");
    }
}