アルゴリズム:大文字の数値変換

import java.util.ArrayList;
import java.util.List;

public class Demo {

    private char ZERO = '0';

    private char ZERO_CN = ' ';

    private String[] NUMBER = { " ", " ", " ", " ", " ", " ", " ", " ", " ", " " };

    private String[] UNIT = { "", " ", " ", " " };

    private String[] MATRIX = { "", " ", " ", " ", " ", " ", " ", " ", " ", " " };

    public String change(long num) {

        if (num < 0) {
            return "";
        }

        List<String> data = new ArrayList<String>();
        
        format(String.valueOf(num), data);
        
        return show(data);
    }

    public void format(String str, List<String> data) {

        int len = str.length();

        if (len == 1) {
            data.add(NUMBER[str.charAt(0) - ZERO]);
            return;
        }

        if (len > 4) {
            format(str.substring(str.length() - 4), data);
            format(str.substring(0, str.length() - 4), data);
            return;
        }

        formatUnit(str, data);
    }

    private void formatUnit(String str, List<String> data) {

        String result = "";

        while (str.length() > 0 && Long.parseLong(str) > 0) {

            if (str.charAt(0) == ZERO) {
                result += NUMBER[str.charAt(0) - ZERO];
                str = String.valueOf(Long.parseLong(str));
                continue;
            }

            result += NUMBER[str.charAt(0) - ZERO] + UNIT[str.length() - 1];

            str = str.substring(1);
        }

        data.add(result);
    }

    private String show(List<String> data) {

        String result = "";
        for (int i = data.size() - 1; i >= 0; i--) {
            String str = data.get(i);
            if (str.length() == 0) {
                continue;
            }
            result += data.get(i) + MATRIX[i];
        }

        return trimZeroCN(result);
    }

    private String trimZeroCN(String str) {

        if (str.length() <= 1) {
            return str;
        }

        char[] ch = str.toCharArray();

        int start = 0;
        int end = str.length() - 1;

        while (ch[start] == ZERO_CN) {
            start++;
        }

        while (ch[end] == ZERO_CN) {
            end--;
        }

        return str.substring(start, end + 1);
    }
}

9223372036854775807	==>	                                   
100000009	==>	    
103050709	==>	             
123456789	==>	                 
103006	==>	       
100006	==>	     
123450	==>	          
123456	==>	           
10000	==>	  
10005	==>	    
12000	==>	    
10045	==>	      
12005	==>	      
12300	==>	      
10345	==>	        
12045	==>	        
12305	==>	        
12340	==>	        
12345	==>	         
1000	==>	  
1004	==>	    
1034	==>	      
1204	==>	      
1230	==>	      
1234	==>	       
123	==>	     
12	==>	   
10	==>	  
6	==>	 
0	==>