• The Idea:
  • Sometimes integers have more digits of accuracy than are needed but truncation isn't appropriate
• An Example:
  • As before, employees are paid a fixed amount per piece, but only for multiples of 10 pieces.
  • But now, to improve employee satisfaction, rounding is used instead of truncation (so 526 pieces will be rounded to 530, not truncated to 520)

• Notation:
  • number denotes the value
  • place denotes the place of interest (e.g., 10s, 100s, etc...)
• Truncation:
  • javaexamples/programmingpatterns/Rounding.java (Fragment: truncated)

                    truncated = (number / place) * place;
            

• The Easy Part:
  • Given the original value, the truncated value, and an appropriate indicator it's easy to find the answer (i.e., increase truncated by place)
• The Indicator:
  • Involves value - truncated and half of place

javaexamples/programmingpatterns/Rounding.java (Fragment: pattern)

            /**
     * Round an int value to a given place (i.e., power of 10).
     *
     * @param number  The number to round
     * @param place   The place to round to (10, 100, 1000, etc...)
     * @return The rounded value
     */
    public static int round(int number, int place) {
        int rounded, truncated;
        
        truncated = (number / place) * place;

        if ((number % place) >= (place / 2)) {
            rounded = truncated + place;
        } else {
            rounded = truncated;
        }

        return rounded;
    }
        

• Code for a Revised Manufacturing Example:
  • javaexamples/programmingpatterns/Rounding.java (Fragment: manufacturingexample)

                    items = 526;
            place = 10;
            rounded = round(items, place);
            

• Tracing a Revised Manufacturing Example:
  • (number/place)*place is (526/10)*10 or 520
  • number % place is 6
  • place / 2 is 5
  • So, the answer is 520 + 10 or 530

• Code for a Revised Year Example:
  • javaexamples/programmingpatterns/Rounding.java (Fragment: yearexample)

                    exact   = (1993 + 93);
            decade  = round(exact,  10);
            century = round(exact, 100);
            

• Tracing the Revised Year Example for the Century:
  • (number/place)*place is (2086/100)*100 or 2000
  • num % place is 86
  • 100 / 2 is 50
  • So, the answer is 2000 + 100 or 2100