import java.util.ArrayList; import java.util.List; /** *Inspired by Python range method. This class provide three constructors to instantiate Range object which are all self explanatory especially for those familiar with the Python range method. * @author Dan Rhamba */ class RangeDemo{ public static void main(String [] args)throws RangeException { Range range = new Range(100, 10, -5); System.out.println(range); } } class RangeException extends Exception { private String message; public RangeException(String message) { this.message = message; } @Override public String getMessage() { return message; } } public class Range { private int startIndex; private int lastIndex; private int step; private List values = new ArrayList<>(); public Range(int lastIndex) throws RangeException { startIndex = 0; this.lastIndex = lastIndex; step = 1; validateArgs(); for (int i = startIndex; i < lastIndex; i++) { values.add(i); } } public Range(int startIndex, int lastIndex) throws RangeException { this.startIndex = startIndex; this.lastIndex = lastIndex; step = (startIndex > lastIndex) ? -1 : 1; validateArgs(); if (step > 0) { for (int i = startIndex; i < lastIndex; i++) { values.add(i); } } else { for (int i = startIndex; i > lastIndex; i--) { values.add(i); } } } public Range(int startIndex, int lastIndex, int step) throws RangeException { this.startIndex = startIndex; this.lastIndex = lastIndex; this.step = step; validateArgs(); if (step > 0) { for (int i = startIndex; i < lastIndex; i += step) { values.add(i); } } else { for (int i = startIndex; i > lastIndex; i += step) { values.add(i); } } } /** * * @throws RangeException if arguments are out of logical range bounds */ private void validateArgs() throws RangeException { if (startIndex > lastIndex & step > 0) { throw new RangeException("Step cannot be positive when lastIndex is less than startIndex"); } else if (startIndex < lastIndex & step < 0) { throw new RangeException("startIndex cannot be less than lastIndex when step is negative."); } else if (step == 0) { throw new RangeException("step cannot be 0."); } } public List toList() { List val = new ArrayList<>(); val.addAll(values); return val; } @Override public String toString(){ return values.toString(); } }

Range class in Java