Iterate through each digit in a number

Question

I am trying to create a program that will tell if a number given to it is a \"Happy Number\" or not. Finding a happy number requires each digit in the number to be squared,

Answer 1

Assuming the number is an integer to begin with:

int num = 56;
String strNum = "" + num;
int strLength = strNum.length();
int sum = 0;

for (int i = 0; i < strLength; ++i) {
  int digit = Integer.parseInt(strNum.charAt(i));
  sum += (digit * digit);
}