GCD (Greatest Common Divisor ) Euclids way
public class GreatestCommonDivisor {

//using euclid's way of calculating GCD
  static int greatestCommonDivisor(int a, int b) {
    int gdivisor = 1, divider, dividend;
    if (a < b) { // the one less is divisor the one greater is dividend
      divider = a;
      dividend = b;
    }
    else {
      divider = b;
      dividend = a;
    }

    if (dividend % divider == 0) { //its the GCD
      return divider;
    }
    else { //proceed further
      greatestCommonDivisor(divider, dividend % divider);
    }
    return gdivisor; //the GCD of the 2 numbers
  }

  public static void main(String args[]) {
    System.out.println(greatestCommonDivisor(5, 144));
  }
}
GCD (Greatest Common Divisor ) Euclids way