JavaAlgorithms/Maths/Average.java

package Maths;

/** Calculate average of a list of numbers */
public class Average {
  private static final double SMALL_VALUE = 0.00001f;

  public static void main(String[] args) {
    assert Math.abs(average(new double[] {3, 6, 9, 12, 15, 18, 21}) - 12) < SMALL_VALUE;
    assert Math.abs(average(new double[] {5, 10, 15, 20, 25, 30, 35}) - 20) < SMALL_VALUE;
    assert Math.abs(average(new double[] {1, 2, 3, 4, 5, 6, 7, 8}) - 4.5) < SMALL_VALUE;
    int[] array = {2, 4, 10};
    assert average(array) == 5;
  }

  /**
   * Calculate average of a list of numbers
   *
   * @param numbers array to store numbers
   * @return mean of given numbers
   */
  public static double average(double[] numbers) {
    double sum = 0;
    for (double number : numbers) {
      sum += number;
    }
    return sum / numbers.length;
  }

  /**
   * find average value of int array
   *
   * @param array the array contains element and the sum does not excess long value limit
   * @return average value
   */
  public static int average(int[] array) {
    long sum = 0;
    for (int i = 0; i < array.length; ++i) {
      sum += array[i];
    }
    return (int) (sum / array.length);
  }
}