Write a program in java to display all the Armstrong numbers from 1 to 1000

Armstrong number is a number that is equal to the sum of cubes of its digits. For example 0, 1, 153, 370,371 and 407 are the Armstrong numbers. 153 = (1*1*1)+(5*5*5)+(3*3*3) = 1 + 125 + 27 = 153. 

class Armstrong_no
{
    public static void main(String args[])
    {
        int num,r,sum;
        System.out.println("1 to 1000 Armstrong no");
        for(int i=1;i<=1000;i++)
        {
       
        num=i;
        sum=0;
        while(num>0)
        {
            r=num%10;
            sum=sum+r*r*r;
            num=num/10;
        }
        if(sum==i)
        System.out.print(i+"\t");
           
        }
    }
}