人民币大小写分析

以下这个程序是我从一个高手那里拿来的,但是处理0的那一部分我实在是看不懂,请各位帮忙,分不多(没有分了,这是全部家档).先谢了.
public class changeToBig{
  public static void  main(String [] args){  
          char[]   hunit={'拾','佰','仟'};         //段内位置表示  
          char[]   vuni{'万','亿'};                                                              //段名表示  
          char[]   digit={'零','壹','贰','叁','肆','伍','陆','柒','捌','玖'};     //数字表示  
          double value = 1001001.00;
          long   midVal =   (long)(value*100);                                                                             //转化成整形  
          String   valStr=String.valueOf(midVal);                                                                 //转化成字符串  
          String   head=valStr.substring(0,valStr.length()-2);                               //取整数部分  
          String   rail=valStr.substring(valStr.length()-2);                                           //取小数部分  
   
          String   prefix="";                                                                                                                                   //整数部分转化的结果  
          String   suffix="";                                                                                                                                     //小数部分转化的结果  
          //处理小数点后面的数  
          if(rail.equals("00")){                                                                                                                         //如果小数部分为0  
              suffix="整";  
          }   else{  
              suffix=digit[rail.charAt(0)-'0']+"角"+digit[rail.charAt(1)-'0']+"分";    //否则把角分转化出来  
          }  
          //处理小数点前面的数  
          char[]   chDig=head.toCharArray();       //把整数部分转化成字符数组  
          char   zero='0';                        //标志'0'表示出现过0  
          byte   zeroSerNum   =   0;            //连续出现0的次数  
        
/////////主要是以下这些看不懂....  for(int   i=0;i<chDig.length;i++){  
                                                 //循环处理每个数字  
              int   idx=(chDig.length-i-1)%4;             //取段内位置  
              int   vidx=(chDig.length-i-1)/4;   //取段位置  
              if(chDig[i]=='0')
              {                                  //如果当前字符是0  
                  zeroSerNum++;                 //连续0次数递增  
                  if(zero   ==   '0')
                  {                                //标志  
                      zero=digit[0];  
                  }else                   
                    if(idx==0   &&   vidx   >0   &&zeroSerNum   <   4)
                  {  
                      prefix   +=   vunit[vidx-1];  
                      zero='0';  
                  }  
                 continue;  
              }  
               zeroSerNum   =   0;                   //连续0次数清零  
               if(zero   !=   '0')   {           //如果标志不为0,则加上,例如万,亿什么的  
                  prefix+=zero;  
                  zero='0';  
              }  
              prefix+=digit[chDig[i]-'0'];     //转化该数字表示  
              if(idx   >   0)   prefix   +=   hunit[idx-1];                                      
              if(idx==0   &&   vidx>0){  
                  prefix+=vunit[vidx-1];      //段结束位置应该加上段名如万,亿  
              }  
          }  
   
          if(prefix.length()   >   0)   prefix   +=   '圆';             //如果整数部分存在,则有圆的字样  
          System.out.println(prefix+suffix);                                                                                                                //返回正确表示  
      }  
      }