Check 0r Find Armstrong Number in Java

public class Arm {
    public static void main(String[] args){

      int num = 370;
      int temp = num;
      int sum=0;
      String power = Integer.toString(num);
      if(num == 0 ){
          System.out.println("Armstrong Number");
      }
      while(temp!=0){
          int digit = temp%10;
         sum = sum+(int)(Math.pow(digit,power.length()));
         temp = temp/10;
      }
      if (num == sum){
          System.out.println("Its a Armstrong Number");
      }else {
          System.out.println("Its not a Armstrong Number");
      }
    }
}