Integer to Roman

public class Solution {
    public String intToRoman(int num) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        String result = new String();
        if(0 == num) return result;
        HashMap<Integer, Character> map = new HashMap<Integer, Character>();
        map.put(1, 'I');
        map.put(5, 'V');
        map.put(10, 'X');
        map.put(50, 'L');
        map.put(100, 'C');
        map.put(500, 'D');
        map.put(1000, 'M');
        int temp = num;
        int current = num%10;
        int bit = 1;
        while(0 != temp)  //divided by 10 until the highest digit
        {
            temp/=10;
            if(3>=current)
            {
                for(int i=0; i<current;i++)
                    result=map.get(bit).toString()+result;  //add the new char to left
            }
            else if(4 == current)
                result=(map.get(bit).toString()+map.get(bit*5).toString()+result);
            else if(5<=current && 8>=current)
            {   
                for(int i=0; i<(current-5); i++)     //add 'I' first
                    result=map.get(bit).toString()+result;
                result=map.get(bit*5).toString()+result;
            }
            else
                result=(map.get(bit).toString()+map.get(bit*10).toString()+result);
            bit*=10;
            current=temp%10;
        }
        return result;
    }
}