package com.wrox.algorithms.iteration;/** * A {@link PowerCalculator} that uses iteration. * */public final class IterativePowerCalculator implements PowerCalculator {    /** The single, publicly accessible, instance of the comparator. */    public static final IterativePowerCalculator INSTANCE = new IterativePowerCalculator();    /**     * Constructor marked private to prevent instantiation.     */    private IterativePowerCalculator() {    }    public int calculate(int base, int exponent) {        assert exponent >= 0 : "exponent can't be < 0";        int result = 1;        for (int i = 0; i < exponent; ++i) {            result *= base;        }        return result;    }}