LeetCode Fraction to Recurring Decimal

Given two integers representing the numerator and denominator of a fraction, return the fraction in string format.

If the fractional part is repeating, enclose the repeating part in parentheses.

For example,

• Given numerator = 1, denominator = 2, return "0.5".
• Given numerator = 2, denominator = 1, return "2".
• Given numerator = 2, denominator = 3, return "0.(6)".

Credits:
Special thanks to @Shangrila for adding this problem and creating all test cases.

public class Solution {
    public String fractionToDecimal(int numerator, int denominator) {
        if (numerator==0) {
            return "0";
        }
        String result="";
        if (numerator<0 ^ denominator<0) {
            result+="-";
        }
        long n=numerator;
        long d=denominator;
        n=Math.abs(n);
        d=Math.abs(d);
        long r=n%d;
        result+=n/d;
        if (r==0) {
            return result;
        }else {
            result+=".";
        }
        HashMap<Long, Integer> map=new HashMap<>();
        while (r>0) {
            if (map.containsKey(r)) {

                result=result.substring(0, map.get(r))+"("+result.substring(map.get(r))+")";
                return result;
            }else {
                map.put(r, result.length());
                r*=10;
                result+=r/d;
                r=r%d;    
            }
        }
        return result;
    }
}