public String getComplementString(String stringToComplement) {
        String complement = "";
        for (int i = 0; i < stringToComplement.length(); i++) {
            Character complementChar = stringToComplement.charAt(i);
            if (complementChar.equals('A')) {
                complement = complement + "T";
            } else if (complementChar.equals('T')) {
                complement = complement + "A";
            } else if (complementChar.equals('C')) {
                complement = complement + "G";
            } else if (complementChar.equals('G')) {
                complement = complement + "C";
            }
        }
        return complement;
    }