Approach :  

public static String intToString(int x) {
    boolean isNegative = false;
    if (x < 0) {
      isNegative = true;
    }

    StringBuilder s = new StringBuilder();
    do {
      s.append((char)('0' + Math.abs(x % 10)));
      x /= 10;
    } while (x != 0);

    if (isNegative) {
      s.append('-'); // Adds the negative sign back.
    }
    s.reverse();
    return s.toString();
}

 

References