RunningAverage

public final class RunningAverage {
		private final int[] values;
		private float average;
		private int index;

		public RunningAverage(int capacity) {
			values = new int[capacity];
			average = 0;
			index = 0;
		}

		public float add(int newValue) {
			int[] values = this.values;
			float length = values.length;
			float average = this.average;
			int index = this.index;

			float newAverage = (((average * length) - values[index]) + newValue) / length;

			values[index] = newValue;

			if (++index >= length) {
				index = 0;
			}

			this.average = newAverage;
			this.index = index;

			return newAverage;
		}
	}