Roman Numeral Representation using Java

几天前，没有事情，就跑到网上看相关的java程序，便看到有个post说，做Roman Numeral很简单。然后就回来试了一下，其实蛮麻烦的。
因为String处理bar其实很难，便把那些小写了。下面便是我尝试的code。

import java.util.HashMap;
import java.util.Scanner;

/**
* Roman Numerals
* This class create Roman numbers object
* and do the corresponding calculations
* Maximum should be less than 1 million
*/
public class RomanNumeral{
 // listed are the fields
 // lower case stand for bar on top
 private static int romanCount=0;
 private int number;
 private String romanString;
 private static HashMap symbolToValue = initSymbolToValue();
 private static char[][] valueToSymbol = initValueToSymbol();

 //constructors
 public RomanNumeral(){
 /**
 * default constructor
 * set number to 0
 */
  number =0;
  romanString = "";
  romanCount++;
 }

 // initialize with a number
 public RomanNumeral(int num){
  number = num;
  romanString = numberToRoman(num);
  romanCount++;
 }

 // initialization with a String,
 public RomanNumeral(String str){
  romanString = str;
  number = romanToNumber(romanString);
  romanCount++;
 }

        public String toString(){
            return romanString;
        }
// from now on are the methods used for the class
 // Accessors and modifiers
 public int getNumber(){
  return number;
 }

 public String getRomanString(){
  return romanString;
 }


 public void setNumber(int num){
  number = num;
  romanString = numberToRoman(number);
 }

 public void setRomanString(String rstr){
  romanString = rstr;
  number = romanToNumber(romanString);
 }

 // Arithmetic methods for Roman Numerals
 public boolean equals(RomanNumeral rn){
  if (number == rn.getNumber())
   return true;
  else return false;
 }

 public int compare(RomanNumeral rn1, RomanNumeral rn2){
 // 1 means greater, 0 means equal, while -1 means smaller
  int num1 = rn1.getNumber(), num2 = rn2.getNumber();
  if(num1>num2)
   return 1;
  else if (num1 < num2)
   return -1;
  else return 0;
 }

 public RomanNumeral add(RomanNumeral rn1){
  return (new RomanNumeral(number+rn1.getNumber()));
 }

 public RomanNumeral subtractedBy(RomanNumeral rn1){
  return (new RomanNumeral(number-rn1.getNumber()));
 }

 public RomanNumeral multipliedBy(RomanNumeral rn1){
  return (new RomanNumeral(number*rn1.getNumber()));
 }

 public RomanNumeral dividedBy(RomanNumeral rn1){
  return (new RomanNumeral(number/rn1.getNumber()));
 }

 // static methods here
 public static int getCount(){
  return romanCount;
 }

 public static RomanNumeral pow(RomanNumeral rn1, RomanNumeral rn2){
  int num = (int)Math.pow(rn1.getNumber(), rn2.getNumber());
  return (new RomanNumeral(num));
 }

 public static HashMap initSymbolToValue(){
  HashMap symToVal = new HashMap(13);

  symToVal.put('I', 1);
  symToVal.put('V', 5);
  symToVal.put('X', 10);
  symToVal.put('L', 50);
  symToVal.put('C', 100);
  symToVal.put('D', 500);
  symToVal.put('M', 1000);
  symToVal.put('v', 5000);
  symToVal.put('x', 10000);
  symToVal.put('l', 50000);
  symToVal.put('c', 100000);
  symToVal.put('d', 500000);
  symToVal.put('m', 1000000);
  return symToVal;
 }

 public static char[][] initValueToSymbol(){
  char[][] valToSym = {
  {'I', 'V', 'X'},
  {'X', 'L', 'C'},
  {'C', 'D', 'M'},
  {'M', 'v', 'x'},
  {'x', 'l', 'c'},
  {'c', 'd', 'm'},
  {'m',},
  };
  return valToSym;
 }

 protected String numberToRoman(int num){
  if (num == 0)
   return "";

  StringBuffer[] strBuf = new StringBuffer[7];
  int count=0;
  do {
   strBuf[count]= new StringBuffer();
   int remainder = num%10;
                        
                        char[] symArr= valueToSymbol[count];
                        
                        String temp;
   if (remainder == 0){
    count++;
    continue;
   }
   else if (remainder <= 3){
    for( ; remainder>0; remainder--)
     strBuf[count].append(symArr[0]);
   }
   else if (remainder ==4){
                                temp = "" + valueToSymbol[count][0]+symArr[1];
    strBuf[count].append(temp);
                        }
   else if (remainder >= 5 && remainder <= 8){
    strBuf[count].append(symArr[1]);
    remainder -= 5;
    for(; remainder>0; remainder--)
        strBuf[count].append(symArr[0]);
   }
   else {
                            temp = ""+symArr[0]+symArr[2];
                            strBuf[count].append(temp);
                        }
                        
   count++;
                        num = num/10;
  } while(num !=0 );

  String resultStr ="";
  for(count--; count>=0; count--){
                   resultStr += strBuf[count].toString();
  }
  return resultStr;
 }


 /* it is assumed that roman string is in upper case*/
 protected int romanToNumber(String roman){
  if (roman.equals(""))
   return 0;
  else if (roman.charAt(0)=='-')
   return -1 * romanToNumber(roman.substring(1));
  else if(roman.length() ==1)
   return symbolToValue.get(roman.charAt(0));

  else {
   if (symbolToValue.get(roman.charAt(0))< symbolToValue.get(roman.charAt(1)))
    return -1 * symbolToValue.get(roman.charAt(0)) + romanToNumber(roman.substring(1));
   else  return  symbolToValue.get(roman.charAt(0)) + romanToNumber(roman.substring(1));
  }
 }



 /*++++++++++++++++++++++++++++++++++++++*/
 public static void main(String[] args) throws Exception{
  RomanNumeral year= new RomanNumeral("MMXI");
  RomanNumeral rnum = new RomanNumeral(1234);
  System.out.println("In the year " + rnum.getRomanString()+ ", Jin is defeatly completed by Mongolians.");
  System.out.println(year.getRomanString() + " the current year, which is "+ year.getNumber()+".");
                System.out.println(year.add(rnum));

                Scanner sc = new Scanner(System.in);
                System.out.println("Please enter a new number for processing=>");
                RomanNumeral rnInput = new RomanNumeral(Integer.parseInt(sc.nextLine()));
                System.out.println(rnInput);
 }
 /*++++++++++++++++++++++++++++++++++++++*/
}

写的不够好，不过真的搞的蛮久的。