Python の range() 関数を Java で (如何に怠惰に書くか) .java

// -*- mode: java; coding: utf-8; -*-

public class RangeArray {

        public static int[] range(int n) {
            return range(0, n, 1);
        }

        public static int[] range(int k, int n) {
            return range(k, n, 1);
        }

        public static int[] range(int start, int stop, int step) {
            if (step == 0) {
                final String message = "range() step argument must not be zero";
                throw new IllegalArgumentException(message);
            }
            int pitch = Math.abs(step);
            int length = Math.abs(stop - start);
            int inc = (start > stop ? -1 : 1) * pitch;
            int value = start;
            int[] array = new int[length / pitch + (length % pitch != 0 ? 1 : 0)];
            for (int i = 0, l = array.length; i < l; i++) {
                array[i] = value;
                value += inc;
            }
            return array;
        }
    }

public class RangeList {

        public static List<Integer> range(final int stop) {
            return range(0, stop, 1);
        }

        public static List<Integer> range(
                final int start,
                final int stop) {
            return range(start, stop, 1);
        }

        public static List<Integer> range(
                final int start,
                final int stop,
                final int step) {
            if (step == 0) {
                final String message = "range() step argument must not be zero";
                throw new IllegalArgumentException(message);
            }
            List<Integer> list = new ArrayList<Integer>();
            int pitch = Math.abs(step);
            int inc = (start > stop ? -1 : 1) * pitch;
            return create(list, start, stop, inc);
        }

        private static List<Integer> create(
                final List<Integer> list,
                final int current,
                final int stop,
                final int step) {
            if (step < 0 ? current <= stop : current >= stop) {
                return list;
            } else {
                list.add(current);
                return create(list, current + step, stop, step);
            }
        }
}